CVE-2015-7220 in Firefox
Summary
by MITRE
Buffer overflow in the XDRBuffer::grow function in js/src/vm/Xdr.cpp in Mozilla Firefox before 43.0 might allow remote attackers to cause a denial of service or possibly have unspecified other impact via crafted JavaScript code.
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Analysis
by VulDB Data Team • 07/01/2022
The vulnerability identified as CVE-2015-7220 represents a critical buffer overflow condition within Mozilla Firefox's JavaScript engine, specifically within the XDRBuffer::grow function located in js/src/vm/Xdr.cpp. This flaw exists in versions prior to Firefox 43.0 and demonstrates a classic memory safety issue that can be exploited through malicious JavaScript code execution. The vulnerability operates at the intersection of application-level memory management and JavaScript interpretation, creating a pathway for attackers to manipulate memory boundaries through crafted input sequences.
The technical implementation of this buffer overflow occurs within the XDR (External Data Representation) buffer management system that Firefox employs for serializing and deserializing JavaScript objects and data structures. The XDRBuffer::grow function is responsible for dynamically expanding buffer capacity when existing memory limits are exceeded during data processing operations. When processing maliciously crafted JavaScript code, the function fails to properly validate buffer boundaries, allowing an attacker to write data beyond allocated memory segments. This condition typically arises from insufficient input validation and inadequate bounds checking mechanisms within the buffer expansion logic, creating opportunities for memory corruption that can be leveraged for arbitrary code execution or system instability.
The operational impact of CVE-2015-7220 extends beyond simple denial of service scenarios, as the vulnerability presents potential for more severe consequences including arbitrary code execution and system compromise. Remote attackers can exploit this weakness by delivering malicious JavaScript content through web pages, email attachments, or other vector mechanisms that trigger the vulnerable code path. The vulnerability's classification under CWE-129 indicates it involves improper validation of the length of input data, while its potential for unspecified other impacts aligns with ATT&CK technique T1059.007 for JavaScript-based execution. The memory corruption resulting from this buffer overflow can lead to unpredictable behavior including application crashes, data corruption, or in more sophisticated exploitation scenarios, complete system compromise through privilege escalation.
Mitigation strategies for CVE-2015-7220 primarily focus on immediate version upgrades to Firefox 43.0 or later, which contain the patched implementation of the XDRBuffer::grow function with proper bounds checking and input validation. Organizations should implement comprehensive patch management procedures to ensure all Firefox installations are updated promptly, as the vulnerability affects all versions prior to the specified release. Additional defensive measures include deploying web application firewalls that can detect and block suspicious JavaScript patterns, implementing content security policies to restrict script execution, and conducting regular security assessments of web applications that may be vulnerable to similar buffer overflow conditions. Network monitoring should be enhanced to detect anomalous JavaScript execution patterns that might indicate exploitation attempts, while security teams should maintain awareness of related vulnerabilities in the JavaScript engine and related components. The vulnerability serves as a reminder of the critical importance of memory safety practices in modern web browsers and the necessity of rigorous input validation mechanisms to prevent buffer overflow conditions that can compromise system integrity.