CVE-2008-7143 in phpBB
Summary
by MITRE
phpBB 2.0.23 includes the session ID in a request to modcp.php when the moderator or administrator closes a thread, which allows remote attackers to hijack the session via a post in the thread containing a URL to a remotely hosted image, which might include the session ID in the Referer header.
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Analysis
by VulDB Data Team • 01/19/2019
The vulnerability described in CVE-2008-7143 represents a critical session management flaw in phpBB version 2.0.23 that enables unauthorized session hijacking through cross-site request forgery techniques. This issue specifically affects the moderation control panel functionality where session identifiers are inadvertently exposed in HTTP requests, creating an attack vector that can be exploited by malicious actors to gain unauthorized access to administrative accounts. The vulnerability stems from the improper handling of session identifiers within the modcp.php script, which fails to properly sanitize or remove session tokens from requests made during thread moderation activities.
The technical exploitation of this vulnerability occurs when a moderator or administrator closes a thread through the moderation control panel, at which point the session ID becomes embedded in the HTTP request headers. When a malicious user posts content containing a remote image reference within the closed thread, the web browser automatically includes the Referer header containing the session ID when requesting the remote image resource. This header information can be captured by the remote server hosting the malicious image, effectively allowing an attacker to obtain the session identifier and subsequently hijack the administrative session. The flaw demonstrates a classic case of information exposure through improper header handling, where sensitive session data is transmitted in cleartext across network boundaries without adequate protection mechanisms.
The operational impact of this vulnerability extends beyond simple session hijacking to encompass potential complete system compromise when administrators are targeted. Since phpBB 2.0.23 was widely deployed across numerous websites and forums, the attack surface was substantial, with attackers able to exploit this flaw to gain full administrative privileges over affected systems. The vulnerability also aligns with several attack patterns documented in the MITRE ATT&CK framework, particularly those related to credential access and privilege escalation through session management weaknesses. This flaw represents a significant security gap in the application's defensive posture, as it undermines the fundamental principle of least privilege and allows attackers to impersonate legitimate users with elevated permissions.
The vulnerability can be classified under CWE-200, which addresses "Information Exposure," and specifically relates to CWE-384, "Session Management Flaw," as well as CWE-310, "Cryptographic Issues." These classifications emphasize the fundamental weakness in how the application handles session identifiers and the exposure of sensitive data through network requests. Organizations affected by this vulnerability should implement immediate mitigations including patching to the latest phpBB versions, implementing proper header sanitization, and establishing secure session management practices. The recommended approach involves removing session identifiers from all outgoing requests, implementing proper CSRF tokens, and ensuring that sensitive data is not transmitted through referer headers or other HTTP headers that may be exposed to remote servers. Additionally, network monitoring should be enhanced to detect anomalous referer header patterns that may indicate exploitation attempts.