CVE-2018-0494 in wget
Summary
by MITRE
GNU Wget before 1.19.5 is prone to a cookie injection vulnerability in the resp_new function in http.c via a \r\n sequence in a continuation line.
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Analysis
by VulDB Data Team • 12/03/2024
The vulnerability identified as CVE-2018-0494 affects GNU Wget versions prior to 1.19.5 and represents a critical cookie injection flaw within the HTTP response handling mechanism. This vulnerability resides in the resp_new function located in the http.c source file, where improper parsing of continuation lines in HTTP responses creates an avenue for malicious cookie manipulation. The flaw specifically manifests when Wget processes HTTP responses containing cookie headers that utilize continuation line sequences, allowing attackers to inject additional cookie data that bypasses normal validation mechanisms.
The technical implementation of this vulnerability stems from inadequate input sanitization and parsing logic within Wget's HTTP client implementation. When processing HTTP responses, the software fails to properly validate the structure of continuation lines in cookie headers, enabling attackers to craft malicious responses that include additional cookie directives. This occurs because the parsing logic does not sufficiently distinguish between legitimate continuation sequences and maliciously crafted cookie injection attempts. The vulnerability operates at the application layer and affects the HTTP protocol handling capabilities of Wget, making it particularly dangerous for automated downloading and web scraping operations that rely on proper HTTP response parsing.
The operational impact of CVE-2018-0494 extends beyond simple cookie manipulation to potentially enable more sophisticated attacks including session hijacking, cross-site scripting exploitation, and unauthorized access to protected resources. When Wget processes maliciously crafted HTTP responses containing injected cookies, the application may inadvertently store or transmit these manipulated cookie values, leading to unauthorized access to web applications or services. This vulnerability is particularly concerning for security tools and automated systems that use Wget for downloading content, as these systems may be exploited to gain unauthorized access to protected resources or to execute malicious commands through manipulated cookie data. The vulnerability aligns with CWE-115, which addresses improper handling of data representation, and can be mapped to ATT&CK technique T1071.004 for application layer protocol manipulation.
Mitigation strategies for this vulnerability require immediate patching of affected Wget installations to version 1.19.5 or later, which contains the necessary fixes to properly validate continuation line sequences in HTTP responses. Organizations should also implement network monitoring to detect anomalous HTTP response patterns that may indicate exploitation attempts. Additional defensive measures include configuring Wget with strict cookie handling policies, implementing proxy servers that validate HTTP responses before they reach Wget clients, and conducting regular security assessments of automated download systems. The vulnerability demonstrates the critical importance of proper input validation in network protocols and highlights the need for robust parsing logic that can distinguish between legitimate protocol extensions and malicious data injection attempts. Security teams should also consider implementing automated patch management systems to ensure timely deployment of security updates across all affected systems.