Confluence Server and Data Center Allow Arbitrary Code Execution

Fortify Security Team
Sep 2, 2021

A vulnerability has been discovered in Confluence Server and Data Center, which could allow for arbitrary code execution. Confluence is a wiki tool used to help teams collaborate and share knowledge efficiently. Successful exploitation of this vulnerability could allow an unauthenticated user to execute arbitrary code on a Confluence Server or Data Center instance. Depending on the privileges associated with the instance, an attacker could view, change, or delete data.

THREAT INTELLIGENCE:
There are currently no reports of this vulnerability being exploited in the wild.

September 3 – UPDATED THREAT INTELLIGENCE:
US Cyber Command has reported mass exploitation of CVE-2021-26084 and anticipates accelerated attack volume.

SYSTEMS AFFECTED:

  • Confluence Server and Data Center all versions prior to 6.13.23
  • Confluence Server and Data Center versions from 6.14.0 prior to 7.4.11
  • Confluence Server and Data Center versions from 7.5.0 prior to 7.11.6
  • Confluence Server and Data Center versions 7.12.x prior to 7.12.5

RISK:
Government:

  • Large and medium government entities: Medium
  • Small government entities: Medium

Businesses:

  • Large and medium business entities: Medium
  • Small business entities: Medium

Home users: N/A

TECHNICAL SUMMARY:
A vulnerability has been discovered in Confluence Server and Data Center Could Allow for Arbitrary Code Execution. An OGNL injection could allow an authenticated user, and in some instances an unauthenticated user, to execute arbitrary code on a Confluence Server or Data Center instance. The vulnerable endpoints can only be accessed if ‘Allow people to sign up to create there account’ is enabled. Successful exploitation of this vulnerability could allow an unauthenticated user to execute arbitrary code on a Confluence Server or Data Center instance. Depending on the privileges associated with the instance, an attacker could view, change, or delete data.

RECOMMENDATIONS:
We recommend the following actions be taken:

  • Apply appropriate patches provided by Atlassian to vulnerable systems immediately after appropriate testing.
  • Run all software as a nonprivileged user (one without administrative privileges) to diminish the effects of a successful attack.
  • Evaluate read, write, and execute permissions on all newly installed software.
  • Apply the Principle of Least Privilege to all systems and services.

REFERENCES:
Atlassian:
https://confluence.atlassian.com/doc/confluence-security-advisory-2021-08-25-1077906215.html

CVE:
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-26084

September 3 – UPDATED REFERENCES:
Twitter:
https://twitter.com/cnmf_cyberalert/status/1433787671785185283

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