CVE-2017-5416 in Firefox
Summary
by MITRE
In certain circumstances a networking event listener can be prematurely released. This appears to result in a null dereference in practice. This vulnerability affects Firefox < 52 and Thunderbird < 52.
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Analysis
by VulDB Data Team • 08/18/2020
The vulnerability identified as CVE-2017-5416 represents a critical memory safety issue affecting Mozilla Firefox and Thunderbird applications prior to version 52. This flaw manifests as a premature release of a networking event listener component within the browser's network stack, creating conditions that can lead to null pointer dereference errors during normal operation. The vulnerability stems from improper handling of reference counting mechanisms in the networking subsystem where event listeners are not properly maintained in memory until their associated network operations complete successfully.
The technical implementation of this vulnerability involves the interaction between the browser's networking layer and its event handling system. When network operations are processed, the system maintains references to event listeners that monitor connection states and handle various networking events. Under specific conditions, these references are prematurely released or marked for garbage collection before the associated network operations have completed, resulting in a scenario where subsequent access to the released listener object causes a null pointer dereference. This type of memory corruption vulnerability falls under the CWE-476 category of NULL Pointer Dereference, which is classified as a common weakness in software security practices.
The operational impact of CVE-2017-5416 extends beyond simple application crashes, as it creates potential attack vectors that could be exploited by malicious actors. When a null dereference occurs in the networking component of a browser, it can lead to unpredictable behavior including application instability, potential information disclosure, or in more severe cases, remote code execution depending on the specific memory layout and exploitation techniques available. The vulnerability affects not only the targeted applications but also represents a broader concern about resource management in complex networking frameworks where asynchronous operations must maintain proper reference semantics throughout their lifecycle.
Security researchers have identified this issue as particularly concerning within the context of browser security models, as it operates at a level that could be leveraged for more sophisticated attacks. The ATT&CK framework categorizes such vulnerabilities under the T1059 category of Command and Scripting Interpreter, as exploitation could potentially involve manipulating network operations to trigger the memory corruption. The vulnerability demonstrates the complexity of managing asynchronous operations in web browsers where multiple threads and event loops must coordinate properly to maintain memory safety. Organizations affected by this vulnerability should prioritize immediate patching of all affected versions, as the window for exploitation remains significant given the widespread use of these applications. The remediation process involves updating to Firefox 52 or later versions, or Thunderbird 52 or later, where the reference counting logic has been corrected to properly maintain networking event listener objects until their associated operations complete successfully.