CVE-2024-11318 Session Hijacking in AbsysNet

CVE-2024-11318 affects AbsysNet version 2.3.1, enabling an Insecure Direct Object Reference (IDOR) vulnerability within the /cgi-bin/ocap/ endpoint. The vulnerability facilitates unauthorized session hijacking by allowing attackers to brute-force session identifiers exposed or predictable within the application's URL structure. Upon successful enumeration, an attacker can hijack an active, authenticated user's session. The scope of the compromise is limited to the duration of the victim's active session; once the victim logs out, the hijacked session becomes invalid. The exploit mechanism has been publicly disclosed and is available for testing via a Python script published by xthalach. Defenders should prioritize auditing the implementation of session management within the /cgi-bin/ocap/ directory and consider restricting access to this endpoint if not required for public-facing functionality.

Attack Chain

1. Attacker performs reconnaissance to identify instances of AbsysNet 2.3.1 exposing the /cgi-bin/ocap/ endpoint.
2. Attacker initiates the brute-force tool against the target URL, specifically targeting the session_id parameter.
3. Attacker sends repeated HTTP GET requests to the /cgi-bin/ocap/ endpoint, iterating through generated or captured session identifier patterns.
4. The application processes the requests; when a valid, active session_id is guessed, the server returns the authenticated session data within the HTML response.
5. Attacker extracts the valid session token or state from the HTML body of the successful response.
6. Attacker utilizes the harvested session token to impersonate the victim, gaining unauthorized access to the application in the context of the user.
7. Attacker maintains access until the victim session is terminated, at which point the hijacked access is revoked.

Impact

Successful exploitation allows for unauthorized access to sensitive data and functions within an active user's account. This vulnerability carries a CVSS 7.5 score and is particularly dangerous because it requires no user interaction or prior authentication. In a library or information management context, this could result in unauthorized viewing of patron information, transaction history, or internal records.

Recommendation

• Deploy a WAF rule to monitor and alert on high-frequency requests originating from a single source to the /cgi-bin/ocap/ endpoint, which may indicate brute-force attempts.
• Audit webserver access logs for anomalous request patterns targeting /cgi-bin/ocap/ with varying session identifiers.
• Update AbsysNet installations to a patched version beyond 2.3.1 to remediate the underlying IDOR vulnerability.
• Implement rate limiting on the /cgi-bin/ocap/ endpoint to mitigate brute-force enumeration of session identifiers.