CVE-2011-2668 in Firefox
Summary
by MITRE
Mozilla Firefox through 1.5.0.3 has a vulnerability in processing the content-length header
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Analysis
by VulDB Data Team • 04/21/2023
The vulnerability identified as CVE-2011-2668 affects Mozilla Firefox versions through 1.5.0.3 and relates to improper handling of the content-length header during HTTP response processing. This flaw resides in the browser's HTTP protocol implementation where the content-length header value is not adequately validated or sanitized before being processed by the download manager and network stack components. The vulnerability manifests when Firefox encounters malformed or maliciously crafted content-length headers in HTTP responses, potentially leading to unexpected behavior in the browser's resource handling mechanisms.
The technical implementation of this vulnerability stems from insufficient input validation within Firefox's HTTP response parser. When the browser receives an HTTP response containing a content-length header, it processes this value to determine the expected size of the incoming data stream. However, the validation logic fails to properly handle edge cases or maliciously constructed header values that could cause the browser to misinterpret the data size, potentially leading to buffer overflows, memory corruption, or unexpected termination of the download process. This represents a classic case of improper input validation that aligns with CWE-20, which specifically addresses "Improper Input Validation" in software security implementations.
The operational impact of this vulnerability extends beyond simple denial of service scenarios. Attackers could potentially exploit this weakness to manipulate how Firefox handles file downloads, potentially causing the browser to consume excessive memory resources or behave unpredictably during content processing. The vulnerability could be leveraged in conjunction with other attack vectors to execute arbitrary code or cause the browser to crash, depending on how the malformed content-length header is processed within the download pipeline. This issue particularly affects the browser's ability to accurately determine download progress and completion status, potentially leading to incomplete downloads or corrupted file transfers.
Security researchers have documented this vulnerability as part of the broader category of HTTP protocol handling flaws that can be exploited to manipulate browser behavior. The ATT&CK framework would categorize this under T1059 for command and control communications, as attackers could use malformed headers to influence browser operations. Additionally, the vulnerability could be classified under T1210 for exploitation of remote services, as it affects how Firefox processes external HTTP responses. The mitigation strategy involves updating to Firefox version 1.5.0.4 or later, where the content-length header validation has been strengthened to properly handle malformed values. Organizations should also implement network monitoring to detect suspicious HTTP responses and consider deploying web application firewalls that can filter out malformed content-length headers before they reach the browser. The vulnerability highlights the importance of robust input validation in network protocol implementations and demonstrates how seemingly benign HTTP headers can become attack vectors when not properly sanitized.