CVE-2013-0779 in Firefox
Summary
by MITRE
The nsCodingStateMachine::NextState function in Mozilla Firefox before 19.0, Thunderbird before 17.0.3, and SeaMonkey before 2.16 allows remote attackers to execute arbitrary code or cause a denial of service (out-of-bounds read) via unspecified vectors.
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Analysis
by VulDB Data Team • 05/05/2021
The vulnerability identified as CVE-2013-0779 represents a critical memory safety issue affecting Mozilla's core encoding handling mechanisms within Firefox, Thunderbird, and SeaMonkey applications. This flaw resides in the nsCodingStateMachine::NextState function which is responsible for managing character encoding state transitions during text processing. The vulnerability manifests as an out-of-bounds read condition that can be exploited by remote attackers to either execute arbitrary code or induce denial of service scenarios. The affected versions of these applications processed input data through the vulnerable encoding state machine without proper bounds checking, creating a pathway for malicious input to trigger memory access violations.
The technical implementation of this vulnerability stems from inadequate input validation within the encoding state transition logic. When processing character encodings such as UTF-8, UTF-16, or other multibyte character sets, the nsCodingStateMachine component maintains internal state information to track decoding progress. The NextState function fails to validate array indices or buffer boundaries before accessing memory locations, allowing crafted input sequences to bypass normal bounds checking mechanisms. This particular flaw falls under the CWE-129 weakness category, specifically addressing improper validation of array indices, and represents a classic example of an out-of-bounds read vulnerability that can be leveraged for code execution through memory corruption attacks.
The operational impact of CVE-2013-0779 extends beyond simple denial of service scenarios to encompass full remote code execution capabilities. Attackers can craft malicious web pages or email content containing specially crafted byte sequences that, when processed by the vulnerable applications, trigger the out-of-bounds read condition. This vulnerability is particularly dangerous in web browser contexts where users may encounter malicious content without explicit awareness. The exploitation typically requires the target application to process the malicious input through its encoding handling components, making it relevant to any scenario involving text processing, web content rendering, or email parsing. This vulnerability aligns with ATT&CK technique T1203 - Exploitation for Client Execution, where attackers leverage application vulnerabilities to execute code on target systems.
Mitigation strategies for CVE-2013-0779 focus primarily on immediate version upgrades to patched releases of the affected Mozilla applications. Users and organizations should prioritize updating Firefox to version 19.0, Thunderbird to 17.0.3, and SeaMonkey to 2.16, which contain the necessary fixes for the encoding state machine implementation. Additionally, administrators should consider implementing network-level protections such as web application firewalls and content filtering solutions that can detect and block malicious input patterns. The vulnerability demonstrates the importance of proper bounds checking in memory-safe programming practices and highlights the need for regular security updates in widely deployed applications. Organizations should also implement automated patch management systems to ensure timely deployment of security fixes and maintain comprehensive monitoring for potential exploitation attempts.