Hafnium – Microsoft Exchange Server 0-Day Vulnerability

OVERVIEW | 0-day

As early as January 6, 2021, multiple Microsoft Exchange 0-day vulnerabilities had been publicly disclosed. These 0-day vulnerabilities were found to be actively exploited by the threat group Hafnium. This appears to be a nation-state attack that is currently targeting as many as 30,000 organizations in the United States and hundreds of thousands worldwide. Based on the current pool of targeted victims, these attacks do not appear to be targeting any specific sectors or countries.

Per BleepingComputer, there are four 0-day vulnerabilities that were being exploited:

  • CVE-2021-26855 is a server-side request forgery (SSRF) vulnerability in Exchange which allowed the attacker to send arbitrary HTTP requests and authenticate as the Exchange server.
  • CVE-2021-26857 is an insecure deserialization vulnerability in the Unified Messaging service. Insecure deserialization is where untrusted user-controllable data is deserialized by a program. Exploiting this vulnerability gave Hafnium the ability to run code as SYSTEM on the Exchange server. This requires administrator permission or another vulnerability to exploit.
  • CVE-2021-26858 is a post-authentication arbitrary file write vulnerability in Exchange. If Hafnium could authenticate with the Exchange server then they could use this vulnerability to write a file to any path on the server. They could authenticate by exploiting the CVE-2021-26855 SSRF vulnerability or by compromising a legitimate admin’s credentials.
  • CVE-2021-27065 is a post-authentication arbitrary file write vulnerability in Exchange. If Hafnium could authenticate with the Exchange server then they could use this vulnerability to write a file to any path on the server. They could authenticate by exploiting the CVE-2021-26855 SSRF vulnerability or by compromising a legitimate admin’s credentials.

Microsoft released patches for the exploited vulnerabilities on March 2, 2021. A PowerShell script called “Test-ProxyLogon.ps1” was also published by Microsoft to run against the Microsoft Exchange Servers for indicators of compromise. At this time, multiple groups of threat actors (other than the Hafnium group) were also known to be exploiting these vulnerabilities to compromised Microsoft Exchange Servers.

Hafnium Attack Details

These attacks began with reconnaissance on vulnerabilities against the potential servers from the adversary. For Hafnium, following the reconnaissance to gain initial access, they dropped webshells onto the affected servers. Based on our research, webshells dropped onto the victim’s servers were mainly variants related to China Chopper-like Webshell scripts.

The adversary was observed to have deployed these webshell scripts within web directory folders to establish persistence within the systems. The team also observed unusual HTTP POST requests of single letter or generically named Javascript files being used as part of the exploit attempt. CrowdStrike has decoded a sample of such scripts returning initial commands being passed to a dropped webshell. SetObject for OABVirtualDirectory commands were being used to point to the malicious JavaScripts. These webshells potentially allow attackers to perform malicious actions or steal data from the compromise servers.

Post exploitation activity such downloading PowerCat from GitHub was observed from this attack. PowerCat is used to connect to a remote server and open connections to the remote server. Activities such as utilization of exchange PowerShell snap-ins were observed to export mailbox data and stolen files were also observed to be compressed prior to exfiltration.

Stronger Together

Proficio’s Threat Intelligence team is continually researching and collecting IOCs with regards to these attacks. We continue to gather the latest IOCs available and many clients have also been providing additional Exchange logs and malicious artifacts, which we have used to find additional indicators to help in our threat hunting. With the indicators gathered, the team is able to quickly identify positive hits such as dropped files in client’s server.

Other than the public IOCs and additional indicators found by the team, we are also looking at other TTPs such as potential download traffic of PowerCat, large data transfers, access to file sharing sites and other unusual traffic that could help to identify the threat. This is an ongoing effort to help identify clients that may have been compromised and ensure our clients are not being targeted.

Precautionary Measures

Prevention is always better than cure. Given these exploits are still actively seen in the wild, we recommend organizations perform patching or upgrades to any on-premise Exchange environments to help mitigate the risk of successful exploit attempts; for those that have been exploited or are unsure of whether their servers have been compromised from these vulnerabilities prior to the patch, we strongly recommend investigating Microsoft Exchange Servers using Microsoft published PowerShell scripts that will scan for any indicators of compromise within the servers. Patch recommendation and PowerShell scripts provided by Microsoft team can be found here:

  • https://msrc-blog.microsoft.com/2021/03/05/microsoft-exchange-server-vulnerabilities-mitigations-march-2021/

For any concerned Proficio clients, please reach out to your assigned Client Success Manager or Security Advisors.

Reference links

https://news.sophos.com/en-us/2021/03/05/hafnium-advice-about-the-new-nation-state-attack/

https://www.theverge.com/2021/3/5/22316189/microsoft-exchange-server-security-exploit-china-attack-30000-organizations

https://www.bleepingcomputer.com/news/security/microsoft-fixes-actively-exploited-exchange-zero-day-bugs-patch-now/

https://www.microsoft.com/security/blog/2021/03/02/hafnium-targeting-exchange-servers/

Phishing in the Wild II

OVERVIEW
Phishing events are commonly seen in the public so the Proficio’s threat intelligence team often receives opportunities to research different type of phishing activities. On the 13th November 2020, a client had requested for assistance on a phishing incidence that had occurred within their environment.

In this blog, we share some of the findings from our own deep-dive investigations into the HTM spear-phishing email campaigns.

PHISHING DETAILS
In this type of phishing attempt, the adversary would send a spear-phishing email with a HTM (.htm) file attach containing a URL link to the victim. Based on the team’s investigation of the incident that was reported, upon clicking on the phishing link it would redirect the victim to a phishing page which was hosted on another domain.

In this incidence, the phishing link was observed to be hosted on the domain “bayleafinternational[.]com” and upon clicking, the page would be redirected to the domain “laikipianorthtvc[.]ac[.]ke”. However, by 18th November 2020, the redirected phishing domain was taken down so instead of the first observed site “laikipianorthtvc[.]ac[.]ke”, it would redirect the user towards the domain “altia[.]in”. A Whois lookup (Figure 1) was performed on the first redirected link “laikipianorthtvc[.]ac[.]ke” and based on the updated date, it is suggested that this site was likely to taken down on 16th November 2020.

Figure 1 - Sample phishing domain

Figure 1 – Sample phishing domain

The team further investigated the redirected phishing link. Simulating access of the phishing domain would display a phishing page that resembles a Microsoft login page (Figure 2). Upon entering the credentials, we noticed that the phishing site would redirect the victim to a URL on the same domain with a URL path containing “/complete?ss=2”. In this incidence that we were investigating, the user was redirected to the request URL “hxxps://altia[.]in/complete?ss=2”. A HTTP POST request could also be identified upon submitting the credentials (Figure 3).

Figure 2 - Redirected fake login page

Figure 2 – Redirected fake login page

 

Test access with response code

Figure 3 – Test access with response code

Similar phishing activities were also found in the wild, with our research suggesting that this phishing campaign appears to have started as far back as 1st September 2020; it is likely this phishing campaign is still ongoing. We have noticed that multiple domains were being used in this phishing campaign, but some of the used and older pages have since been taken down.

Comparing the phishing activities observed with those seen in the wild, aside from the same fake Microsoft login page used, the phishing links appears to share similar naming formats as follows:

  • Initial URL from email
    • <domain>/<base64-encoded victim’s email address>
  • Redirected phishing page
    • < phishing domain>/?ss=2&ea=<victim email address>&session=<session ID>
  • Redirected complete page
    • <phishing domain>/complete?ss=2

MITRE ATT&CK FRAMEWORK
The following framework is produced based on the investigated incidence:

Tactics  Techniques  Use 
Reconnaissance [TA0043]  Phishing for Information: Spearphishing Link [T1598.003] The phishing email contains a HTM file with a phishing link that leads to a fake login page used to steal credentials
Defense Evasion [TA0005]  Masquerading: Match legitimate name or location [T1036.005] The phishing email contains the use of a htm files with the file name containing the client’s domain.
Initial access [TA0001]  Phishing: Spearphishing Link [T1566.002] The adversaries utilize spear phishing emails and redirect victims to credential harvesting sites.

 

PRECAUTIONARY MEASURES
Anyone can fall victim to a phishing attack. Cybercriminals offer try and catch unsuspecting individuals by sending a phishing email from a reputable or known users that they wouldn’t expect to be compromised. It is advisable to safeguard yourself and your organization to avoid being the next victim from phishing attacks and credential theft. We would recommend organization to consider the following measures if this has seen within your environment.

  • Educate your employees and users to improve cybersecurity awareness.
    • Remind users to report any suspicious emails received, even from other employees, to their cyber-security team.
  • Apply content filters on email gateways and email systems to prevent malicious content from reaching users and reduce the chance of a possible compromise.
  • Always verify any suspicious emails through a different channel such as calling the supposed sender for verification.
  • If your organization is expecting legitimate emails from the senders, filter by email subjects and quarantine emails sent from those compromised senders to anyone outside of an expected recipient list.
  • Reach out to any legitimate sender that appear have their account(s) compromised and instruct them to take action to secure their account(s).
  • Make use of Multi-Factor Authentication to secure email and other user credentials.
  • Make use of network segmentation alongside the zero-trust model.

Ryuk Ransomware

OVERVIEW
Ryuk ransomware was first discovered in the wild in 2018. It is known for using manual hacking techniques and open-source tools to move laterally through private networks and gain administrative access to as many systems as possible before initiating the file encryption.

This ransomware group was one that did not stop attacks on healthcare organizations despite the Coronavirus pandemic in 2020, made clear by their recent attack against Universal Health Services (UHS). In this blog, we will share the common IOCs for this type of attack and ways to stay protected.

RANSOMWARE DETAILS
Since 2019, the most common method for Ryuk threat actors to gain entry to a victim’s environment is with the use of Trickbot and Emotet malware, often starting with phishing attacks. In the case of the UHS attack, both Emotet and TrickBot were detected within the UHS’ environment.

The attack chain often starts with delivering Emotet to a victim host via phishing email, which subsequently downloads Trickbot onto the host. After harvesting data, Trickbot opens a reverse shell to provide Ryuk ransomware threat actors with entry to the victim’s environment, allowing the actors to manually deploy the ransomware on the victim host.

Ryuk ransomware has been found to contain commands for killing services related to antivirus products, and Trickbot has the capability to disable Microsoft Defender as well. A UHS employee has stated online that during the attack, “multiple antivirus programs were disabled”.

Ryuk Ransomware Commands Example

Fig 1. An example of commands in Ryuk ransomware

According another UHS employee, one of the infected computers displayed a ransom note that read “Shadow of the Universe”, which is similar to the phrase “balance of shadow universe” seen in previous Ryuk ransom notes. Names of files were observed being appended with the file extension “.ryk”, which is the extension used by Ryuk ransomware after successfully encrypting a file.

Ryuk Ransomware Note Example

Figure 2 – Example of a ransom note

While there are limited details on the UHS attack, there are some common activities and IOCs of Ryuk ransomware attacks involving Trickbot and Emotet:

  • Phishing email containing Microsoft Office attachments (.doc, .xls etc.) with Macros
  • PowerShell commands executed by Macros
  • Downloading of PowerShell Empire/Cobalt Strike/PsExec
  • Exploitation of EternalBlue vulnerability which is over port 445 (SMB)
  • Unusual scheduled tasks, registry keys created
  • Recurring traffic towards Trickbot C2 servers over ports such as ports 446, 447, 449, 8082
  • Privilege escalation
  • Files with the file extension “.ryk”
  • “RyukReadMe.txt” or “RyukReadMe.html”

PRECAUTIONARY MEASURES
Prevention is better than cure. It is advisable to safeguard yourself and your organization to avoid being the next victim of this ransomware attacks. We would recommend the following measures:

  • Keep your anti-virus software / EDR solutions and other security tools installed on the systems updated for detection and prevention from the spread of ransomware
  • Consider Managed EDR services that will enable you to quickly react and contain any ransomware vendor
    • These services can also play a big part in monitoring and alerting on attacked vectors used as a distribution method
  • Have a cold or distributed backup system in place
    • At a minimum, have backups separate from production systems for your critical files or systems
  • Keep your operating systems up to date on the latest security patches
  • Make use of network segmentation alongside the zero-trust model
  • Close unnecessary network ports to reduce entry points for attackers
  • Apply content filters on email gateways and email systems to prevent malicious content from reaching users and reduce the chance of a possible compromise
  • Educate your employees and users to improve cybersecurity awareness

REFERENCES

  • https://www.bleepingcomputer.com/news/security/uhs-hospitals-hit-by-reported-country-wide-ryuk-ransomware-attack/
  • https://techcrunch.com/2020/09/28/universal-health-services-ransomware/
  • https://www.crowdstrike.com/blog/big-game-hunting-with-ryuk-another-lucrative-targeted-ransomware/
  • https://research.checkpoint.com/2018/ryuk-ransomware-targeted-campaign-break/
  • https://www.cybereason.com/blog/triple-threat-emotet-deploys-trickbot-to-steal-data-spread-ryuk-ransomware
  • https://www.bleepingcomputer.com/news/security/new-trickbot-version-focuses-on-microsofts-windows-defender/
  • https://www.microsoft.com/security/blog/2020/03/05/human-operated-ransomware-attacks-a-preventable-disaster/
  • https://www.cpomagazine.com/cyber-security/ryuk-ransomware-still-targeting-hospitals-during-the-coronavirus-pandemic/
  • https://www.bleepingcomputer.com/news/security/ryuk-ransomware-keeps-targeting-hospitals-during-the-pandemic/
  • https://www.bleepingcomputer.com/news/security/ryuk-ransomware-attacked-epiq-global-via-trickbot-infection/

Typeform Phishing Campaign

OVERVIEW
In recent years, phishing campaign comes in different types and forms. The attackers are known to utilize free online tools and a variety of methods in hope to harvest credentials out from the victims.

On 16 August 2020, a relatively new spear-phishing campaign was detected which appears to utilize a free online tool – Typeform. The attacker created and hosted fake online forms to harvest victims’ credentials.

In this blog, we share some of the findings from our own deep-dive investigations into the attack activities that we have observed.

PHISHING DETAILS
Our investigation showed that victims would receive variants of emails, which can contain a URL link or an attachment that would redirect the victim to a phishing page. The phishing pages observed would inform the victim about a document that was sent through OneDrive in a PDF format.

Typeform Phished Email Example

Figure 1 – An example of phished email received

From our investigation, we have seen events where upon a successful phishing attempt, the compromised host would be used to subsequently broadcast the phishing email to all other employee using the organization email domain.

We have also seen events where the victim executed the phished PDF attachment in which the PDF would display a Microsoft labelled document with a “Open in OneDrive” button. Our investigation shows that clicking the button redirects to a phishing subdomain in Typeform with domain names such as

  • “hXXps://document-signonline[dot]typeform[dot]com”
  • ”hXXps://microsofonedrive6575[dot]typeform[dot]com”.
Typefrom Phishing Attachement Example

Figure 2 – An example of the attachment

Further investigations by the team reveals interesting network behaviour. Upon successful access to the phishing site and the user starts filling the phishing form, the page loads the domain ending with the URL parameter “/start-submission”. The phishing form first prompts for the user’s email address and then their password. Once the credentials are filled in, a button is displayed for the user to click on in order to send the inputs and view a document on the website. Clicking the button loads the domain ending with the URL parameter “/complete-submission”. Observing this traffic would represent a complete cycle whereby the victim has accessed and provided the credentials to the phished sites.

DETECTION AND DISCOVERY EFFORTS
Proficio’s Threat Intelligence Team collected several different IOCs to identify potential access to the phishing sites. The IOCs include URL parameters and IP addresses.

The most notable indicator of accessing the phishing page was the sequence of redirections that occur after clicking the initial phishing link. Based on this, we were able to identify potential phishing attempts with higher certainty despite the limited visibility allowed for an MDRP/MSSP like Proficio.

From our investigation, this campaign appears to target by organization rather than random individuals, as we had observed the phishing emails being sent to multiple employees within an organization together in one wave. Even if the emails were blocked, there were no repeated attempts to send the emails to the targets. This campaign does not appear to target any specific industry sector.

PRECAUTIONARY MEASURES
This could have happened to anyone of us that works in any organization whom we would unexpectedly receive phishing email send by reputable or known users that were being compromised. It is advisable to safeguard you and your organization to avoid being the next victim from phishing attacks and credential theft. We would recommend organization to consider the following measures if this has seen within your environment.

  • Educate your employees and users to improve cybersecurity awareness.
  • Apply content filters on email gateways and email systems to prevent malicious content from reaching users and reduce the chance of a possible compromise.
  • Educate users to report any suspicious emails received, even from other employees, to their cyber-security team.
  • Always verify any suspicious emails through a different channel such as calling the supposed sender for verification.
  • Quarantine emails sent from those compromised senders to anyone outside of an expected recipient list of filtering by email subjects if your organization is expecting legitimate emails from the senders.
  • Reach out to any legitimate sender that appear have their account(s) compromised and instruct them to take action to secure their account(s).
  • Make use of Multi-Factor Authentication to secure email and other user credentials
  • Make use of network segmentation alongside the zero-trust model

WastedLocker Ransomware

OVERVIEW
First discovered in May, WastedLocker ransomware is a relatively new strain from the group known as Evil Corp, which was previously associated with the Dridex banking Trojan and BitPaymer ransomware. This ransomware group was brought to our attention with the recent ransomware attack against Garmin. In our research, we discovered why these targeted attacks are even harder to defend against. Read on to learn what to look for and how to avoid this new strain.

RANSOMWARE DETAILS
WastedLocker attacks start with a drive-by compromise to gain initial entry. The attackers use the SocGholish framework to hack legitimate websites that display fake software update alerts to visitors. Attempting to download these fake alerts will deliver PowerShell scripts onto the user’s device, which subsequently download Cobalt Strike. Cobalt Strike then allows the attackers to gain access, move laterally through the target’s network, and deliver the WastedLocker ransomware to the victim host.

Before deploying the ransomware, the attackers perform the following tasks within the target’s network:

  • Escalates privileges via UAC bypass method
  • Disables Windows Defender
  • Gathers information about victim’s environment
  • Performs credential dumping

WastedLocker attackers have also been observed in previous attacks to utilize living-off-the-land (LOFT) tools to perform tasks. For example, using the Windows Sysinternals tool PsExec to disable Windows Defender, using PowerShell and WMIC to profile the target’s environment.

Upon successful encryption of a victim’s file, the ransomware appends a file extension that is a combination of the target organization’s name and the string “wasted”. In the case of the Garmin attack, the file extension “.garminwasted” was appended to encrypted files. For each encrypted file, the ransomware also creates a ransom note with the same name appended with “_info” at the end of the file extension, such as “.garminwasted_info”.

Example of a ransom note

Figure 1 – Example of a ransom note

Aside from encryption, the WastedLocker ransomware is also capable of deleting Windows shadow copies to wipe backups and file snapshots to make recovery impossible.

The method of payment provided to decrypt WastedLocker is to contact one of the emails listed within the ransom notes. As of now, email addresses that have been used by the attackers are can belong to either ProtonMail, Eclipso, Tutanota, or Airmail.

Unlike many other ransomwares this year, WastedLocker ransomware does not steal victims’ files but simply encrypt them. However, it is worth noting that WastedLocker attacks are highly targeted and ransomware samples used are each customized for the target organization. This means that standard IOCs such as the file hashes of previous samples would not be very helpful or useful in detections.

PRECAUTIONARY MEASURES
Prevention is better than cure. It is advisable to safeguard you and your organization to avoid being the next victim of this ransomware attacks. We would recommend organization to consider the following measures.

  • Keep your anti-virus software / EDR solutions and other security tools installed on the systems updated for detection and prevention from the spread of ransomware.
  • Make use of a managed EDR service to quickly react and contain any ransomware vendor
  • Managed EDR services can also play a big part in monitoring and alerting on attacked vectors used as a distribution method
  • Have a cold or distributed backup system in place, or at minimum have backups separate from production systems, for your critical files or systems.
  • Keeping your operating systems up to date on the latest security patches.
  • Make use of network segmentation alongside the zero-trust model.
  • Close unnecessary network ports to reduce entry points for attackers.
  • Apply content filters on email gateways and email systems to prevent malicious content from reaching users and reduce the chance of a possible compromise.
  • Educate your employees and users to improve cybersecurity awareness.

ABOUT PROFICIO

Proficio’s Managed, Detection and Response (MDR) solution surpasses the capabilities of traditional Managed Security Services Providers (MSSPs). Our MDR service is powered by next-generation cybersecurity technology and our security experts partner with you to become an extension of your team, continuously monitoring and investigating threats from our global networks of security operations centers. Learn More About Proficio’s Services

REFERENCES

  • https://research.nccgroup.com/2020/06/23/wastedlocker-a-new-ransomware-variant-developed-by-the-evil-corp-group/
  • https://symantec-enterprise-blogs.security.com/blogs/threat-intelligence/wastedlocker-ransomware-us
  • https://www.bleepingcomputer.com/news/security/new-wastedlocker-ransomware-distributed-via-fake-program-updates/
  • https://www.bleepingcomputer.com/news/security/dozens-of-us-news-sites-hacked-in-wastedlocker-ransomware-attacks/
  • https://www.bleepingcomputer.com/news/security/garmin-outage-caused-by-confirmed-wastedlocker-ransomware-attack/
  • https://labs.sentinelone.com/wastedlocker-ransomware-abusing-ads-and-ntfs-file-attributes/

Phishing in the Wild

OVERVIEW
It’s no secret that phishing is one of the most common types of cyberattacks, both to individuals and organizations. According to the 2020 Verizon Data Breach Investigation Report, one out of four breaches involved phishing. So when Proficio’s Threat Intelligence Team received a client request, asking for assistance with a phishing incident, we conducted a thorough investigation on the specific threat actor. Below we share the key findings from our deep-dive investigation, including the hooks used and key targets for this campaign.

PHISHING CAMPAIGN DETAILS
The threat actor appears to be utilizing compromised user accounts within the targeted organization to send out phishing emails to internal contacts within their mailing list. We observed that such phishing emails sent by the legitimate, but compromised, user accounts would contain a download image that resembles the original PDF download button (Figure 1).

Sample email received

Figure 1 – Sample email received

The Proficio’s Threat Intelligence Team dissected the email received, observing the below PCAP from a simulated access attempt against the download link (Figure 2). While the download button masquerades as an attachment, it appears to be a request URL link. The threat actor employs pretty standard social engineering “hooks” to creates a false sense of urgency with words such as “advise ASAP”. The purpose, of course, is to lure the victim into quickly clicking on the button without thinking too much.

Sample PCAP from email received

Figure 2 – Sample PCAP of email received

Our analysis of the PCAP file (generated upon clicking on the download image seen from the email) reveals a redirect to an external request URL. Simulated access against the external request URL in a controlled environment reveal a redirect to a website with a “CLICK HERE TO VIEW” button. This phishing “hook” resembles a secure document intended for the victim to access.

Simulated access to request URL

Figure 3 – Simulated access to request URL

If a victim clicks on the “CLICK HERE TO VIEW” button, they would be directed to a fake Microsoft login page. When we input fake credentials into the login page, the adversary directs the user to an error page and requests for the credentials to be submitted again. We believe that the second credential request is meant to direct the user to the real Microsoft login page, a setup very similar to those practiced by other phishing campaigns. There are no other redirections observed subsequently.

Fake Microsoft login page

Figure 4 – Fake Microsoft login page

DETECTION AND DISCOVERY EFFORTS
Proficio’s Threat Intelligence Team collected several different IOCs to identify potential access to the phishing sites. The IOCs includes known domain, IP addresses and unique URL parameter used in this phishing attempt.

Our investigation revealed that this campaign targets organizations rather than random individuals, as we observed that the phishing emails were sent to multiple employees within an organization together in one wave. Our analysis and study of the threat actor’s infrastructure and TTPs reveal that the threat actor conducting the phishing campaign appears to be interested in targeting specific geographic regions. We have identified the presence of several interesting strings such as “AUSTRALIA” and “YANKEE” used by the threat actor in their request URLs to organize their data depending on the geographic region associated with their target.

During our extensive investigations, we discovered the phishing emails were sent to multiple clients containing multiple different phished domains which ends with “/DOCUMENT.html”. Simulated access towards all the discovered sites exhibits the same redirection behaviour. Most of the identified activity was from inbound phishing emails. In most cases, we did not identify any click-through traffic that would indicate a potentially successful phishing attack.

While the threat actor appears to be interested in only a few geographic region, they do not appear to target any specific industry sector. We have identified multiple clients who have received emails from this phishing campaign. The sectors targeted by the threat actor most frequently were:

  • Healthcare
  • Commercial Services
  • Real Estate

We will continue to keep an eye out for other phishing campaigns and intrusions that could be associated with this particular threat actor.

PRECAUTIONARY MEASURES & RECOMMENDATIONS
Phishing remains a popular attack vector because it continues to work very effectively. Anyone could receive phishing emails, and they could be sent by reputable or known users that were unknowingly compromised. It is advisable to take proactive steps to safeguard you and your organization to avoid being the next victim of a phishing attack or credential theft. We would recommend organizations to consider the following measures to protect themselves from phishing attacks.

  • Educate your employees and users to improve cybersecurity awareness.
  • Apply content filters on email gateways and email systems to prevent malicious content from reaching users and reduce the chance of a possible compromise.
  • Educate users to report any suspicious emails received, even from other employees, to their cyber-security team.
  • Always verify any suspicious emails through a different channel such as calling the supposed sender for verification.
  • Quarantine emails sent from those compromised senders to anyone outside of an expected recipient list of filtering by email subjects if your organization is expecting legitimate emails from the senders.
  • Reach out to any legitimate sender that appear have their account(s) compromised and instruct them to take action to secure their account(s).
  • Make use of Multi-Factor Authentication to secure email and other user credentials
  • Make use of network segmentation alongside the zero-trust model

Proficio Vulnerability and Advisory Report

CVE-2020-2021 PAN-OS: Authentication Bypass in SAML Authentication
PURPOSE:
The purpose of this report is to provide vendor specific advisories and vulnerability information that may be relevant to the security of a device(s) deployed within your network environment. Along with information about the vulnerability related issues, Proficio will provide recommended actions to either resolve, mitigate or workaround the vulnerability as provided by the vendor.

Please let us know if you have any questions or concerns about the information below. If you are a current MSS customer, please let us know if you would like assistance with implementation. Submit a change request to prosoc@proficio.com .

ADVISORY DETAILS

Reported Vulnerability

Date: 2020 June 29

Severity: Critical

CVE-2020-2021 PAN-OS: Authentication Bypass in SAML Authentication

Summary:

When Security Assertion Markup Language (SAML) authentication is enabled and the ‘Validate Identity Provider Certificate’ option is disabled (unchecked), improper verification of signatures in PAN-OS SAML authentication enables an unauthenticated network-based attacker to access protected resources. The attacker must have network access to the vulnerable server to exploit this vulnerability.

Affected Products

GlobalProtect Gateway,

GlobalProtect Portal,

GlobalProtect Clientless VPN,

Authentication and Captive Portal,

PAN-OS next-generation firewalls (PA-Series, VM-Series) and Panorama web interfaces,

Prisma Access

Work Around

If SAML or SSO is configured; proceed to the recommendation section below.

This article will illustrate the actions to confirm the configuration is present.

https://knowledgebase.paloaltonetworks.com/KCSArticleDetail?id=kA14u0000008UXP

Affected/Fixed Software

This issue affects PAN-OS 9.1 versions earlier than PAN-OS 9.1.3; PAN-OS 9.0 versions earlier than PAN-OS 9.0.9; PAN-OS 8.1 versions earlier than PAN-OS 8.1.15, and all versions of PAN-OS 8.0 (EOL). This issue does not affect PAN-OS 7.1.

This issue is fixed in PAN-OS 8.1.15, PAN-OS 9.0.9, PAN-OS 9.1.3, and all later versions.

Details

If SAML or SSO is not configured, no action required.  If SAML or SSO is configured, the proceed to the recommendation section below.

Proficio Recommendation

If SAML or SSO is configured, follow the directions below:

Using a different authentication method and disabling SAML authentication will completely mitigate the issue.

Until an upgrade can be performed, applying both these mitigations (a) and (b) eliminates the configuration required for exposure to this vulnerability:

(a) Ensure that the ‘Identity Provider Certificate’ is configured. Configuring the ‘Identity Provider Certificate’ is an essential part of a secure SAML authentication configuration.

(b) If the identity provider (IdP) certificate is a certificate authority (CA) signed certificate, then ensure that the ‘Validate Identity Provider Certificate’ option is enabled in the SAML Identity Provider Server Profile. Many popular IdPs generate self-signed IdP certificates by default and the ‘Validate Identity Provider Certificate’ option cannot be enabled. Additional steps may be required to use a certificate signed by a CA. This certificate can be signed by an internal enterprise CA, the CA on the PAN-OS, or a public CA. Instructions to configure a CA-issued certificate on IdPs are available at https://knowledgebase.paloaltonetworks.com/KCSArticleDetail?id=kA14u0000008UXP.

Upgrading to a fixed version of PAN-OS software prevents any future configuration changes related to SAML that inadvertently expose protected services to attacks.

Details on Threat Group That Claims to Have Obtained President Trump’s Legal Documents

REvil/Sodinokibi Ransomware
OVERVIEW
The REvil/Sodinokibi threat group has taken ransomware attacks to a new level. While most variants, like the recent strain of DoppelPaymer ransomware, encrypt victim’s files, Proficio’s Threat Intelligence Team has seen an uptick of strains that also steal data to further pressure victims into paying ransoms. This group, infamously known as the one claiming to have obtained President Donald Trump’s legal documents, more recently attacked the law firm Grubman Shire Meiselas & Sacks (GSMLaw) which resulted in the exfiltration of multiple celebrities’ legal documents.

In this blog, we will be sharing additional details we discovered based on our research on the REvil/Sodinokibi ransomware.

RANSOMWARE DETAILS
REvil/Sodinokibi ransomware was discovered back in April 2019, where it was initially found to propagate via exploitation of a vulnerability in Oracle WebLogic. REvil/Sodinokibi is a ransomware-as-a-service (RaaS) and was suspected to be associated with GandCrab, a RaaS that had shut down operations in May 2019. REvil/Sodinokibi was found to share similar codes with GandCrab ransomware, such as the random URL generation.

Within the past year, REvil/Sodinokibi threat actors have been observed to utilize multiple techniques to spread ransomware to targets. Based on our research, some of distribution methods used are:

  • Oracle WebLogic vulnerability (CVE-2019-2725)
  • Malspam campaigns
  • Hack WordPress sites and fake forum posts containing a link to the ransomware installer
  • Breach managed service providers (MSPs) via exposed RDP
  • Webroot SecureAnywhere console in MSPs that deploys ransomware on the MSPs’ customers systems
  • RIG exploit kit
  • Pulse Secure VPN vulnerability (CVE-2019-11510)

Once the ransomware is delivered to a victim device, it can perform the following tasks:

  • Exploit the CVE-2018-8453 vulnerability to elevate privileges
  • Terminate blacklisted processes prior to encryption to eliminate resource conflicts
  • Wipe the contents of blacklisted folders
  • Encrypt non-whitelisted files and folders on local storage devices and network shares
  • Exfiltrate basic host information

Upon successful encryption of the victim’s files, the ransomware appends a randomly generated file extension to the file name made up of 5 to 10 alphanumeric characters. A ransom note is dropped onto the victim’s device with instructions on how the victim can pay the ransom.

Example of a ransom note

Figure 1 – Example of a ransom note

REvil/Sodinokibi threat actors usually provide two methods of payment. The first method is to access a Tor site using a Tor browser; the other is to use their secondary website. Earlier attacks provided “decryptor[.]top” as their secondary payment site, however more recent attacks appear to have switched to “decryptor[.]cc” instead.

Since January 2020, the threat actors behind the REvil/Sodinokibi ransomware have started to publish data stolen from victims that did not pay their ransom on time. This method of pressuring victims was inspired by Maze ransomware, which started this trend among ransomwares.

ADDITIONAL ACTIONS BY THE THREAT INTELLIGENCE TEAM

PRECAUTIONARY AND DETECTION MEASURES
Prevention is better than a cure, and given the popularity of ransomware attacks, you always need to be prepared. When possible, you must safeguard yourself and your organization to avoid being the next victim of ransomware attacks. We recommendthe use of a managed EDR service to help you deal with any ransomware attack quickly.

We also recommend organizations consider the following measures:

  • Keep your anti-virus software / EDR solutions and other security tools update to date to provide detection and prevention from the spread of ransomware.
  • Make use of managed EDR services to quickly react and contain any ransomware identified before any major damage can be done.
    • Managed EDR services can also play a big part in monitoring and alerting on attack vectors that are often used as distribution methods for ransomware.
  • Perform regular backups on critical files and systems.
  • Keep your operating systems up to date with the latest security patches.
  • Make use of network segmentation alongside the zero-trust model.
  • Close any unnecessary network ports to reduce entry points for attackers.
  • Apply content filters on email gateways and email systems to prevent malicious content from reaching users and reduce the chance of a possible compromise.
  • Educate your employees and users to improve cybersecurity awareness.

 

REFERENCES

  • https://blog.talosintelligence.com/2019/04/sodinokibi-ransomware-exploits-weblogic.html
  • https://www.bleepingcomputer.com/news/security/sodinokibi-ransomware-distributed-by-hackers-posing-as-german-bsi/
  • https://www.bleepingcomputer.com/news/security/sodinokibi-ransomware-spreads-via-fake-forums-on-hacked-sites/
  • https://www.zdnet.com/article/ransomware-gang-hacks-msps-to-deploy-ransomware-on-customer-systems/
  • https://www.bleepingcomputer.com/news/security/sodinokibi-ransomware-targeting-asia-via-the-rig-exploit-kit/
  • https://www.zdnet.com/article/vpn-warning-revil-ransomware-targets-unpatched-pulse-secure-vpn-servers/
  • https://www.secureworks.com/research/revil-sodinokibi-ransomware
  • https://www.bleepingcomputer.com/news/security/sodinokibi-ransomware-publishes-stolen-data-for-the-first-time/
  • https://www.bleepingcomputer.com/news/security/shared-code-links-sodinokibi-to-gandcrab-minus-the-fun-and-games/
  • https://blog.redteam.pl/2020/05/sodinokibi-revil-ransomware.html?m=1
  • https://www.pcrisk.com/removal-guides/14942-sodinokibi-ransomware

DoppelPaymer Ransomware

OVERVIEW
Recently, Proficio’s Threat Intelligence Team has observed a surge in ransomware cases that take advantage of the current COVID-19 situation. In this blog, we will discuss a variant of ransomware named “DoppelPaymer”, which has significantly raised its popularity over the last month, and provide additional details discovered during our research.

RANSOMWARE DETAILS
“DoppelPaymer” is said to be the evolution from “BitPaymer Ransomware”. This strain of ransomware is an enterprise-targeting variant. Based on its history of attacks and the information within the ransom notes, we believe that the threat actor group is targeting English-speaking victims.

While earlier builds of the malware were identified back in April 2019, the first known victims of DoppelPaymer ransomware were seen in June 2019. DoppelPaymer ransomware is likely a variant of BitPaymer Ransomware, where initial ransom notes would contain the string of text “BitPaymer”. The name “DoppelPaymer” was given by researchers to identify this new variant of ransomware found in the wild. Following that, the threat actor appears to have adopted this name and has changed the string of text from “BitPaymer” to “DoppelPaymer” within the ransom notes. Based on the similarities between both ransomware variants, the threat actor groups for DoppelPaymer are suspected to be likely a split from INDRIK SPIDER cybercrime group.

DoppelPaymer ransomware is known to consist of both Dridex and BitPaymer source code. Several other interesting traits that were observed, including:

  • Encryption method 2048-bit RSA + 256-bit AES
  • Encrypted files are renamed with a “.locked” extension
  • Latest version of variants mark data with “.doppeled” appendix
  • Ability to terminate processes and services that may interfere with file encryption using the technique ProcessHacker

DoppelPaymer ransomware is usually dropped by the Dridex trojan; however, this ransomware is not limited to one distribution method. Based on our research, the following are some of the distribution methods that have been observed over the year:

  • Insecure RDP configuration
  • Email spam and malicious attachments
  • Deceptive downloads
  • Botnets
  • Exploits
  • Malicious advertisement
  • Web injects
  • Fake updates
  • Repackaged
  • Infected installers

Upon successful infection and encryption of data on the victim’s computer, the victim’s files would be renamed, and a ransom note in text file format could be found within the victim’s system.

Ransom notes sample

Figure 1 Ransom notes

It’s interesting to note that there is no ransom amount stated within the text file. Instead, a list of instructions was being provided to the victim to follow strictly. The victims were requested to download “Tor Browser” and to subsequently type into an address bar provided to access the DoppelPaymer portal.

Accessing Tor link in Ransom Notes Sample

Figure 2 Accessing Tor link found in ransom notes

DoppelPaymer Ransomware Payment Portal Sample

Figure 3 DoppelPaymer Ransomware Payment Portal

After the portal was accessed from the Tor browser, the victim would be provided with several key pieces of information, such as a countdown timer for a “special price”, a unique reference ID used to identify the victim, the ransom amount and a BTC address where the ransom payment can be sent to.

Further research on DoppelPaymer ransomware reveals that, in the earlier days, victims who are not willing to pay the ransom would have their data sold on the darknet. Following the trends from various ransomware groups such as Maze , the DoppelPaymer threat actor group was inspired to launch a public website for use as a shaming platform to victims who are not willing to pay the ransom.

A video demonstration of file encryption can also be seen on YouTube.


PRECAUTIONARY MEASURES
Prevention is always better than a cure. It is advisable to safeguard yourself and your organization to avoid being the next victim of a ransomware attack. We advise using a managed EDR service to better prepare yourself for dealing with a ransomware attack. We also recommend organizations consider the following measures:

  • Keep your anti-virus software / EDR solutions and other security tools installed on the systems updated for detection and prevention from the spread of ransomware.
  • Make use of a managed EDR service to quickly react and contain any ransomware vendor
  • Managed EDR services can also play a big part in monitoring and alerting on attacked vectors used as a distribution method
  • Perform regular backups on critical files and systems.
  • Keep your operating systems up to date with the latest security patches.
  • Make use of network segmentation alongside the zero-trust model.
  • Apply content filters on email gateways and email systems to prevent malicious content from reaching users and reduce the chance of a possible compromise.
  • Educate your employees and users to improve cybersecurity awareness.

For the latest information from our Threat Intelligence Team on the DoppelPaymer attacks and other threats, please visit our Twitter Feed.

“Voicemail” Phishing Campaign

OVERVIEW
On February 28th, the Proficio Threat Intelligence Team identified a new spear-phishing campaign that pretends to be sending a voicemail to targeted recipients.

In this blog, we share some of the findings from our deep-dive investigations into the attack activities that we have observed for this campaign.

PHISHING DETAILS
The attack starts with a phishing email pretending to send the recipient a voicemail. The email has a sender address starting with “voice@” and a subject containing text such as “New VM was sent” or “Voice Receiver”. The email contains a URL link which when clicked, redirects the recipient to a phishing page that resembles a Microsoft login page. The victim’s credentials are then stolen when entered and submitted on the fake login page.

An example of a fake Microsoft login page

Figure 1a and 1b

Figure 1 – An example of the fake login page (a) and real (b)

The initial phishing attempt is merely the first step of the adversary’s intrusion attempt. After successfully gaining user login, the threat actor responsible uses the credentials obtained to conduct a targeted spear phishing campaign against other employees within the victim’s organization.

DETECTION AND DISCOVERY EFFORTS
Proficio’s Threat Intelligence Team gathered and researched a number of different IOCs to identify potential access to the phishing sites. The IOCs included email subject strings, known domains, URL parameters and IP addresses. These IOCs were used to kickstart the detection and discovery phase of our threat hunting campaign. We identified several potential victims and performed deep-dive investigations on each potential victims identified.

The most notable and useful indicator we generated was the sequence of redirections that occurred after clicking the initial phishing link. Such activity strongly indicated a successful access attempt to the phishing page by the victim(s), and we were thus able to identify potentially successful phishing attempts with a high level of confidence despite the limited visibility of the dataset at our disposal.

Our investigations indicate that this campaign appears to focus on targeting organizations rather than random individuals, as we observed that the phishing emails were being sent to multiple employees within an organization together in a single wave. The adversary does not appear to be targeting any specific organization as there were no repeated attempts to send the emails to the targets even if the emails were blocked or did not result in a successful click-through.

No specific industry sector was targeted; we identified several victims of this campaign, all from different sectors:

  • Banking and Financial
  • Technology
  • Commercial Services
  • Real Estate
  • Healthcare

All clients that we identified had a successful clickthrough activity of this phishing campaign have been notified. If you would like to know more about this campaign and what we have found, please reach out to your Client Success Manager or Security Advisor.

FUTURE PRECAUTIONARY MEASURES
Such phishing campaigns are not uncommon, and have been heightened in the past month where multiple phishing campaigns are using COVID-19 to lure victims. The use of COVID-19 as a phishing hook has been very effective in generating click-throughs for attackers’ phishing campaigns. To avoid being the next victim of credential theft, you can put into place safeguards to protect yourself and your organization from phishing attacks.

We would recommend the following measures:

  • To improve cybersecurity awareness, educate your employees and users.
  • To prevent malicious content from reaching users and reduce the chance of a possible compromise, apply content filters on email gateways and systems.
  • If any suspicious emails are received, report them to your security team so they can notify other employees in the organization of the threat.
  • Always verify such suspicious emails through a different channel.