CVE-2007-3422 in WebAPP
Summary
by MITRE
The getcgi function in cgi-bin/cgi-lib/subs.pl in web-app.org WebAPP before 0.9.9.7 attempts to parse query strings that contain (1) non-printing characters, (2) certain printing characters that do not commonly occur in URLs, or (3) invalid URL encoding sequences, which has unknown impact and remote attack vectors.
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Analysis
by VulDB Data Team • 08/24/2017
The vulnerability identified as CVE-2007-3422 resides within the getcgi function of the web-app.org WebAPP software version 0.9.9.6 and earlier. This flaw manifests in the cgi-bin/cgi-lib/subs.pl script where the getcgi function fails to properly validate and sanitize query string parameters. The function exhibits problematic behavior when processing input containing non-printing characters, uncommon printing characters typically absent from standard url encoding, or malformed url encoding sequences. This represents a classic input validation vulnerability that can potentially allow attackers to manipulate the application's parsing logic through crafted malicious query parameters.
The technical nature of this vulnerability stems from inadequate input sanitization within the cgi parsing routine. When the getcgi function encounters query strings with non-printing characters such as control codes or unusual ascii values, or when it processes url encoding sequences that do not conform to standard specifications, the function's parsing mechanism may behave unpredictably. This can lead to various security implications including potential injection attacks, data corruption, or unexpected application behavior that could be exploited by remote attackers. The vulnerability falls under the category of improper input validation as classified by CWE-20, which represents one of the most common software security weaknesses.
The operational impact of this vulnerability extends to remote attack scenarios where malicious actors can potentially exploit the flawed parsing mechanism without requiring local system access. Attackers might craft specially formatted urls containing the problematic character sequences to trigger unexpected behavior in the web application. This could potentially lead to information disclosure, denial of service conditions, or in more severe cases, arbitrary code execution depending on how the application handles the malformed input. The remote nature of the attack vector means that exploitation can occur from any location with internet connectivity, making it particularly dangerous for publicly accessible web applications.
Security practitioners should implement several mitigation strategies to address this vulnerability. The most effective immediate solution involves upgrading to WebAPP version 0.9.9.7 or later, which contains the necessary patches to properly handle malformed query strings. Additionally, organizations should implement robust input validation at multiple layers including web application firewalls, application-level sanitization, and proper url encoding validation. The implementation of proper character set validation and the rejection of non-standard url encoding sequences can prevent exploitation attempts. Organizations should also consider implementing monitoring and logging mechanisms to detect unusual query string patterns that might indicate attempted exploitation of this vulnerability. This vulnerability aligns with attack patterns documented in the attack tree framework where input manipulation represents a common initial exploitation vector for web applications.