CVE-2007-1349 in Apache Test
Summary
by MITRE
PerlRun.pm in Apache mod_perl before 1.30, and RegistryCooker.pm in mod_perl 2.x, does not properly escape PATH_INFO before use in a regular expression, which allows remote attackers to cause a denial of service (resource consumption) via a crafted URI.
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Analysis
by VulDB Data Team • 07/17/2019
The vulnerability described in CVE-2007-1349 represents a classic example of improper input validation and sanitization within web application frameworks, specifically affecting the mod_perl module ecosystem that bridges perl scripting capabilities with apache web servers. This flaw exists in the PerlRun.pm component of mod_perl versions prior to 1.30 and the RegistryCooker.pm component in mod_perl 2.x, both of which are widely used for embedding perl code within apache web servers. The vulnerability stems from the failure to properly escape special characters in the PATH_INFO parameter, which is a component of the HTTP request URI that contains additional path information beyond the initial request path. When attackers craft malicious URIs containing specially formatted PATH_INFO data, the vulnerable code processes these inputs without adequate sanitization before incorporating them into regular expression operations.
The technical exploitation of this vulnerability occurs through the manipulation of the PATH_INFO component within HTTP requests, where attackers can inject characters that have special meanings in regular expression syntax such as parentheses, backslashes, or other metacharacters. When the mod_perl modules process these inputs through their regular expression engines without proper escaping, the regular expression engine becomes susceptible to catastrophic backtracking scenarios. This occurs because the unescaped special characters cause the regular expression engine to perform an exponential number of operations, leading to massive resource consumption and ultimately resulting in denial of service conditions where system resources such as cpu cycles and memory become exhausted. The vulnerability specifically maps to CWE-185, which addresses improper regular expression handling, and represents a form of regex denial of service attack that can be amplified through carefully crafted inputs.
The operational impact of this vulnerability extends beyond simple service disruption to encompass broader security implications for web server infrastructure that relies on mod_perl for dynamic content generation. Attackers can exploit this vulnerability to consume system resources continuously, potentially leading to complete system unavailability and affecting other services running on the same server. The vulnerability affects a significant portion of apache installations that utilize mod_perl for perl-based web applications, making it particularly dangerous in environments where multiple applications depend on the same server infrastructure. The attack vector is particularly insidious because it requires no authentication or special privileges, allowing any remote attacker to exploit the vulnerability through simple HTTP requests containing crafted PATH_INFO parameters.
Mitigation strategies for CVE-2007-1349 primarily focus on upgrading affected mod_perl installations to versions that properly escape PATH_INFO data before regular expression processing, specifically targeting mod_perl 1.30 and later versions or mod_perl 2.x releases that include the RegistryCooker.pm fixes. Organizations should implement input validation mechanisms that sanitize all PATH_INFO components before they are processed by regular expression engines, and consider implementing rate limiting and resource monitoring to detect potential exploitation attempts. Network security controls such as web application firewalls can help detect and block suspicious URI patterns, while system administrators should monitor for unusual resource consumption patterns that may indicate exploitation. The vulnerability demonstrates the critical importance of proper input sanitization in web application frameworks and aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and emphasizes the need for robust security practices in server-side scripting environments that handle user-provided data.