A vulnerability in Atlassian’s Questions for Confluence app has been found that includes hardcoded credentials that remote attackers can exploit to access the Confluence Server or Confluence Data Center it is hosted on. The versions of Questions for Confluence with this vulnerability unpatched are 2.7.34, 2.7.35, and 3.0.2. Atlassian have released a security advisory rating this vulnerability as critical, which is the highest severity in their rating structure.
Tracked as CVE-2022-26138, this bug allows remote, unauthenticated attackers to access all content in a confluence user group. The flaw in the app creates a Confluence user account with the username disabledsystemuser, and a hardcoded password. The original purpose for this existing in the app is so that administrators could more easily migrate data from the Confluence Cloud. This disabledsystemuser account is also added to the Confluence-users group, which grants permissions to view and edit non-restricted pages. The hardcoded password that belongs to this account has been released online, meaning that any remote attacker can now abuse this system to access any page in the Confluence-users group and harvest any information stored here.
Patches for this vulnerability exist, so all users of this app should update to a non-vulnerable version as soon as possible. The Cybersecurity and Infrastructure Security Agency (CISA), have added this vulnerability to their Known Exploited Vulnerabilities list, and have released a security advisory asking users to update this app immediately.
Atlassian have warned that uninstalling the Questions for Confluence app does not fix this vulnerability, as the disabledsystemuser account is not removed when the app is uninstalled. This account can however be deleted or disabled manually. To disable the account, users should go to User Management in Settings, and search for the user account disabledsystemuser, then click Disable. However, this is not always an option if the Confluence version is a read-only connection to an external directory.
Alternatively the user account can be deleted, which can be done on any directory type, takes a few minutes to process, and cannot be undone. For an internal Confluence directory with read/write to an external directory, go to User Management in Settings, and search for the user account disabledsystemuser, then click Delete. For a read-only external directory, or multiple external directories, the user needs to first be removed from each external directory they are in. In Confluence, go to Settings > User Management > Unsynced from directory, and search for disabledsystemuser. The option to delete this user should now appear, but will take a few minutes to process after selected.