CVE-2006-0293 in Firefox
Summary
by MITRE
The function allocation code (js_NewFunction in jsfun.c) in Firefox 1.5 allows attackers to cause a denial of service (memory corruption) and possibly execute arbitrary code via user-defined methods that trigger garbage collection in a way that operates on freed objects.
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Analysis
by VulDB Data Team • 06/14/2019
The vulnerability identified as CVE-2006-0293 represents a critical memory corruption flaw within the JavaScript engine of Firefox 1.5 browsers. This issue stems from improper handling of function allocation within the js_NewFunction function located in the jsfun.c source file. The vulnerability operates by manipulating user-defined methods in a manner that triggers garbage collection processes while simultaneously operating on memory objects that have already been freed, creating a dangerous scenario where memory integrity is compromised. The flaw is categorized under CWE-125 as an out-of-bounds read condition, which directly relates to the improper memory management practices that allow attackers to manipulate the JavaScript engine's memory allocation and deallocation processes. This vulnerability demonstrates a classic heap-based memory corruption issue that can be exploited through carefully crafted JavaScript code that leverages the garbage collection mechanism to access freed memory locations.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enabling arbitrary code execution on vulnerable systems. When attackers construct specific JavaScript methods that trigger garbage collection at precise moments during function allocation, they can cause the browser to access memory that has already been deallocated, leading to unpredictable behavior including memory corruption, crashes, or more sinister exploitation opportunities. The vulnerability specifically targets the JavaScript engine's memory management system, making it particularly dangerous as it can be exploited through web content without requiring any special privileges or user interaction beyond visiting a malicious website. This type of vulnerability aligns with ATT&CK technique T1059.007 for JavaScript and T1566 for phishing with malicious content, as it can be delivered through malicious web pages that trigger the vulnerable code path during normal browser operation.
The exploitation of this vulnerability requires a sophisticated understanding of JavaScript engine internals and memory management patterns within Firefox 1.5. Attackers must craft JavaScript code that creates function objects in a specific sequence that will trigger garbage collection when freed objects are still referenced, creating a window of opportunity for memory corruption. The vulnerability's potential for arbitrary code execution stems from the ability to manipulate memory layout through controlled garbage collection cycles, allowing attackers to overwrite critical memory structures or inject malicious code into the browser's execution environment. Security researchers have noted that this vulnerability represents a significant weakness in Firefox's JavaScript engine memory management, as it demonstrates inadequate bounds checking and memory lifecycle management during garbage collection operations. The flaw essentially creates a race condition between memory allocation and deallocation processes that can be exploited to manipulate the JavaScript engine's internal state, making it a prime target for advanced persistent threat actors seeking to establish footholds within compromised systems.
Mitigation strategies for this vulnerability primarily involve immediate browser updates to patched versions that address the memory management issues within the JavaScript engine. Organizations should implement comprehensive patch management protocols to ensure all Firefox installations are updated to versions that contain the necessary memory safety improvements. Additional protective measures include implementing content security policies that restrict the execution of potentially malicious JavaScript code, deploying web application firewalls to filter suspicious content, and utilizing browser security extensions that can detect and block known exploitation patterns. The vulnerability highlights the importance of proper memory management in browser engines and serves as a reminder of the critical need for robust input validation and memory lifecycle management in complex software systems. Security teams should also consider implementing monitoring solutions that can detect unusual garbage collection patterns or memory access violations that may indicate exploitation attempts, as the vulnerability's exploitation often manifests through subtle memory corruption patterns that are difficult to detect without proper monitoring infrastructure.