Atlassian Confluence: authentication bypass flaw under attack

What is affected

Atlassian Confluence is mostly run by companies, schools and public bodies, not on home computers. You are unlikely to have it yourself, but organisations that hold your data may. Breaches that start with flaws like this one are how personal data ends up leaked.

Atlassian Questions For Confluence App has hard-coded credentials, exposing the username and password in plaintext. A remote unauthenticated attacker can use these credentials to log into Confluence and access all content accessible to users in the confluence-users group.

What an attacker can do

This is a authentication bypass flaw. It lets an attacker get in without a valid username and password and act as a legitimate user, often as an administrator.

How it is reached

Over the internet or network

Access the attacker needs

No account needed

Does the victim have to do something?

No, works without the victim doing anything

What to do

1. At home: nothing to install. Keep your own devices updated and use a different password for every service, so that a breach at one organisation does not open your other accounts.
2. If you administer Atlassian Confluence at work: apply the vendor's fix or mitigation now and review logs for signs of compromise, because the flaw was being exploited before it was listed.
3. If the product is past its support date and no fix exists, take it off the internet or retire it.

Apply updates per vendor instructions.

Vendor advisories and fixes

• confluence.atlassian.comconfluence.atlassian.com/doc/questions-for-confluence-security-advisory-2022-07-20-1142446

How urgent is it

CISA added this vulnerability to its Known Exploited Vulnerabilities catalogue on July 29, 2022, which means there is reliable evidence of attacks in the wild. US federal agencies must fix it by August 19, 2022, a deadline that has already passed. That deadline does not bind anyone else, but it shows how seriously the agency rates it.

The EPSS model estimates a 98% probability that this flaw will be exploited somewhere in the next 30 days. That is higher than 99.9% of all scored vulnerabilities.

Its CVSS severity score is 9.8 out of 10 (critical), as recorded in the US National Vulnerability Database.

Technical description

The Atlassian Questions For Confluence app for Confluence Server and Data Center creates a Confluence user account in the confluence-users group with the username disabledsystemuser and a hardcoded password. A remote, unauthenticated attacker with knowledge of the hardcoded password could exploit this to log into Confluence and access all content accessible to users in the confluence-users group. This user account is created when installing versions 2.7.34, 2.7.35, and 3.0.2 of the app.