CVE-2008-5017 in Firefox
Summary
by MITRE
Integer overflow in xpcom/io/nsEscape.cpp in the browser engine in Mozilla Firefox 3.x before 3.0.4, Firefox 2.x before 2.0.0.18, Thunderbird 2.x before 2.0.0.18, and SeaMonkey 1.x before 1.1.13 allows remote attackers to cause a denial of service (crash) via unknown vectors.
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Analysis
by VulDB Data Team • 08/20/2019
The vulnerability identified as CVE-2008-5017 represents a critical integer overflow condition within the XPCOM (Cross-Platform Component Object Model) I/O subsystem of Mozilla Firefox and related applications. This flaw exists in the nsEscape.cpp file which handles URL and data URI encoding operations, specifically affecting versions of Firefox 3.x prior to 3.0.4, Firefox 2.x prior to 2.0.0.18, Thunderbird 2.x prior to 2.0.0.18, and SeaMonkey 1.x prior to 1.1.13. The integer overflow occurs during the processing of encoded data, creating a condition where an attacker can manipulate input parameters to cause the application to allocate insufficient memory for processing operations, ultimately leading to application instability.
The technical implementation of this vulnerability stems from improper handling of integer arithmetic within the encoding functions that process URL components and data URIs. When the application encounters specially crafted input data, the integer overflow results in a negative or excessively large value being used as a memory allocation size parameter. This condition causes the application to attempt to allocate memory in a manner that exceeds the system's capacity or creates invalid memory access patterns, leading to immediate application termination. The flaw falls under the CWE-190 category of Integer Overflow or Wraparound, which specifically addresses situations where integer arithmetic produces results that exceed the maximum value that can be represented by the data type.
From an operational perspective, this vulnerability presents a significant denial of service threat that can be exploited by remote attackers without requiring authentication or specialized privileges. The attack vector involves sending maliciously crafted web content or email messages containing specially formatted URLs or data URIs that trigger the vulnerable code path. When executed successfully, the vulnerability causes the affected application to crash immediately, rendering the browser or email client unusable until manual restart occurs. This type of attack aligns with ATT&CK technique T1499.001 for Network Denial of Service, where adversaries leverage application flaws to disrupt service availability.
The impact extends beyond simple service disruption as this vulnerability could potentially be leveraged as a precursor to more sophisticated attacks. While the primary effect is a crash, the integer overflow condition creates an environment where additional memory corruption could occur, potentially allowing for arbitrary code execution in some scenarios. Security researchers have documented that such integer overflows often serve as entry points for more complex exploitation techniques, particularly when combined with other vulnerabilities present in the same codebase. Organizations using affected versions of these Mozilla applications face significant risk of service interruption and potential compromise, especially in environments where these applications are critical for business operations.
Mitigation strategies for CVE-2008-5017 primarily focus on immediate patch deployment, as the vulnerability was addressed through official security updates released by Mozilla. System administrators should prioritize updating all affected applications to their patched versions, ensuring that all users have access to the latest security releases. Additionally, network administrators can implement content filtering measures to block suspicious URLs and data URI content, though this approach provides only partial protection as the vulnerability can be triggered through various input vectors. Organizations should also consider implementing application whitelisting policies that restrict execution of untrusted code and maintain comprehensive monitoring of application crash events that could indicate exploitation attempts. The vulnerability demonstrates the importance of proper input validation and integer arithmetic handling in security-critical software components, reinforcing the need for regular security assessments and code reviews to identify similar flaws in other system components.