Atlassian Confluence Vulnerability Exploited (CVE-2023-22518)

THE THREAT

On November 6th, Atlassian confirmed that threat actors are now actively exploiting a recently disclosed critical Atlassian Confluence vulnerability. The exploited vulnerability, CVE-2023-22518 (CVSS: 10), is tracked as an Improper Authorization vulnerability in Confluence Data Center and Servers. Exploitation of this vulnerability allows an unauthenticated attacker to reset Confluence and create a Confluence instance administrator account.

Atlassian stated that observed attacks resulted in the deployment of ransomware. Multiple security organizations have identified Cerber ransomware following exploitation of CVE-2023-22518 [2]. As exploitation has now been confirmed, it is critical that organizations, using Atlassian Confluence, update to a secure version immediately.

What we’re doing about it

• eSentire MDR for Network has rules in place to identify exploit attempts
• eSentire Managed Vulnerability Service (MVS) has plugins in place to identify this vulnerability
• IP addresses associated with real-world attacks are blocked via the eSentire Global Deny list
• The eSentire Threat Response Unit (TRU) is performing threat hunts across the eSentire client base
• eSentire MDR for Network and Endpoint have rules in place for Cerber ransomware
• BlueSteel, via eSentire MDR for Endpoint, identifies malicious PowerShell use
• The eSentire Threat Intelligence team is actively tracking this vulnerability for additional details and detection opportunities

What you should do about it

• After performing a business impact review, update to a secure Confluence version
  • Fixed Confluence Data Center and Server versions are as follows 7.19.16, 8.3.4, 8.4.4, 8.5.3, and 8.6.1
• If patching is not immediately possible, alternative mitigations are provided in the Atlassian disclosure page
• Deploy EDR solutions to all supported assets in order to assist in the identification of post-exploitation activity

Additional information.

CVE-2023-22518 was initially disclosed on October 31st, 2023. The first signs of exploitation have been traced back to November 5th. All versions of Confluence Data Center and Server are affected by this vulnerability, with the exclusion of Atlassian Cloud sites. Cloud Confluence sites accessed via the “atlassian.net” domain are not impacted.

In known incidents, threat actors exploited CVE-2023-22518 for initial access into victim organizations. This was followed by reconnaissance commands, execution of PowerShell commands, and the download and execution of a script leading to ransomware deployment. At this time, there is no indication that data exfiltration occurs prior to ransomware deployment. There is a high probability that exploitation will be widespread, as threat actors target all vulnerable exposed instances.

According to Atlassian, fraudulently created administrator accounts may perform a variety of actions leading to “a full loss of confidentiality, integrity and availability”. While exploitation has only been observed leading to the deployment of Cerber ransomware, widespread exploitation by other threat actor groups will likely occur in the immediate future.

References:

[1] https://confluence.atlassian.com/security/cve-2023-22518-improper-authorization-vulnerability-in-confluence-data-center-and-server-1311473907.html
[2] https://redcanary.com/blog/confluence-exploit-ransomware/