Horizon Alert
Summary of the vulnerability and why it matters
A vulnerability in Concrete CMS allows a malicious administrator to inject malicious HTML into the system, potentially leading to unauthorized access to user login data. This could happen if an attacker gains administrative privileges and manipulates the OAuth integration name, which is then displayed to users during login.
- Rogue administrator can spy on logins.
- Affects systems using OAuth.
- Requires administrator access.
Attack Path
How an attacker could exploit the issue
A malicious administrator can exploit this vulnerability by entering specially crafted HTML into the OAuth integration name field. This crafted HTML will then be rendered on pages that display the integration name, allowing the attacker to inject malicious scripts that can steal session cookies or redirect users.
- Requires administrative access.
- Exploits OAuth integration name field.
- Target relies on admin actions.
Live Threat
Current exploitation, exposure, and threat context
This stored XSS vulnerability in Concrete CMS, affecting OAuth integration names, presents a moderate threat. While requiring administrative control to initially exploit, the vulnerability could allow a malicious administrator to snoop on login submissions through crafted integration names. The exploit requires specific conditions, such as a compromised administrative account and a user interaction to trigger the XSS.
- Requires admin access for setup.
- User interaction needed for exploitation.
- Vulnerability is older with no recent exploitation signals.
Priority actions
Operational Fix
Recommended remediation, mitigation, and detection steps
Prioritize reviewing logs for signs of unauthorized administrative access or attempts to exploit the OAuth integration for data exfiltration, given the high impact and critical nature of stored XSS in this context. Focus immediate efforts on identifying and isolating any Concrete CMS instances running version 9.5.0 or below.
- Audit admin users and OAuth configurations.
- Isolate or take offline affected services.
- Monitor for suspicious administrative activity.
