CVE-2008-1591 in PostNuke
Summary
by MITRE
The pnVarPrepForStore function in PostNuke 0.764 and earlier skips input sanitization when magic_quotes_runtime is enabled, which allows remote attackers to conduct SQL injection attacks and execute arbitrary SQL commands via input associated with server variables, as demonstrated by the CLIENT_IP HTTP header (HTTP_CLIENT_IP variable).
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Analysis
by VulDB Data Team • 10/20/2024
The vulnerability identified as CVE-2008-1591 represents a critical security flaw in PostNuke versions 0.764 and earlier, specifically within the pnVarPrepForStore function. This function is responsible for preparing variable data for storage in the database, but it fails to properly sanitize input when the magic_quotes_runtime PHP configuration directive is enabled. The issue stems from a fundamental misunderstanding of how PHP's magic quotes feature interacts with application-level input validation mechanisms, creating a dangerous bypass condition that undermines the intended security controls.
The technical flaw manifests when the magic_quotes_runtime directive is enabled in PHP, which automatically escapes certain characters in runtime data. The pnVarPrepForStore function incorrectly assumes that because PHP is already escaping input, additional sanitization is unnecessary. This assumption proves catastrophic as it allows malicious actors to inject SQL commands through HTTP headers, particularly the CLIENT_IP header which maps to the HTTP_CLIENT_IP variable. The vulnerability operates at the intersection of PHP configuration settings and application-level security controls, creating a scenario where the system's built-in protections actually weaken its security posture.
Operationally, this vulnerability enables remote attackers to execute arbitrary SQL commands against the affected PostNuke application's database. The attack vector specifically targets server variables that are commonly used for logging and tracking purposes, making it particularly dangerous as these variables are often populated with user-supplied data. An attacker can manipulate the CLIENT_IP HTTP header to inject malicious SQL syntax, potentially leading to data theft, unauthorized access, database modification, or complete system compromise. The vulnerability's impact extends beyond simple data extraction as it can be leveraged to escalate privileges and gain deeper access to the underlying system infrastructure.
The security implications of this vulnerability align with CWE-89, which describes SQL injection flaws, and can be mapped to ATT&CK technique T1071.004 for application layer protocol manipulation. Organizations running affected PostNuke versions face significant risk as this vulnerability can be exploited without requiring authentication, making it particularly attractive to automated attack tools. The flaw demonstrates a classic case of improper input validation where the system's defensive mechanisms are misconfigured rather than simply absent, creating a false sense of security. Remediation requires either disabling magic_quotes_runtime or implementing proper input sanitization that functions correctly regardless of PHP configuration settings, with the latter approach being more robust for long-term security.
This vulnerability underscores the importance of defensive programming practices and the dangers of relying on PHP's automatic escaping features without proper application-level validation. The flaw serves as a reminder that security controls must be designed to work correctly across all configuration scenarios rather than assuming specific environmental conditions. Organizations should implement comprehensive input validation at multiple layers, including both application-level and database-level controls, to ensure that security is maintained regardless of underlying PHP configurations. The vulnerability also highlights the critical need for regular security audits and updates, as PostNuke 0.764 and earlier versions are no longer supported and contain numerous other security flaws that compound the risk.