CVE-2018-1302 in HTTP Server
Summary
by MITRE
When an HTTP/2 stream was destroyed after being handled, the Apache HTTP Server prior to version 2.4.30 could have written a NULL pointer potentially to an already freed memory. The memory pools maintained by the server make this vulnerability hard to trigger in usual configurations, the reporter and the team could not reproduce it outside debug builds, so it is classified as low risk.
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Analysis
by VulDB Data Team • 02/24/2023
The vulnerability identified as CVE-2018-1302 represents a memory safety issue within the Apache HTTP Server version 2.4.29 and earlier, specifically concerning the handling of HTTP/2 streams. This flaw manifests during the destruction phase of HTTP/2 streams that have already been processed, creating a scenario where the server might attempt to write to a NULL pointer that could potentially point to memory that has already been freed. The technical nature of this vulnerability places it within the realm of memory corruption issues that can lead to unpredictable behavior and potential exploitation.
The root cause of this vulnerability stems from improper memory management within the Apache HTTP Server's HTTP/2 implementation. When an HTTP/2 stream is destroyed after processing, the server's memory pool management system fails to properly handle the cleanup sequence, resulting in a situation where a NULL pointer dereference could occur. This issue is particularly insidious because it involves the interaction between the server's internal memory management mechanisms and the HTTP/2 protocol handling code. The vulnerability is classified as a NULL pointer dereference, which is a well-known software flaw that can lead to application crashes or potentially more severe consequences if exploited.
The operational impact of CVE-2018-1302 is considered low risk by the Apache team due to the specific conditions required for exploitation. The memory pool architecture used by the Apache HTTP Server makes this vulnerability difficult to trigger under normal operating conditions, as the server's memory management system typically prevents the exact sequence of events necessary for the NULL pointer dereference to occur. The vulnerability's trigger conditions are so specific that the original reporter and development team could not reproduce the issue outside of debug builds, indicating that the normal runtime environment provides sufficient protections against exploitation. This characteristic aligns with CWE-476, which describes NULL pointer dereference vulnerabilities, and demonstrates how certain architectural features can mitigate potential security risks.
The mitigation strategy for CVE-2018-1302 primarily involves upgrading to Apache HTTP Server version 2.4.30 or later, where the vulnerability has been addressed through improved memory management and stream destruction handling. System administrators should prioritize this update as part of their regular security maintenance procedures, particularly in environments where HTTP/2 is actively used. The fix implemented in version 2.4.30 specifically targets the memory pool handling during HTTP/2 stream destruction, ensuring that pointers are properly validated and managed before any memory operations occur. Organizations should also consider implementing monitoring systems to detect any unusual behavior patterns that might indicate attempted exploitation of similar memory corruption vulnerabilities, aligning with the ATT&CK framework's approach to identifying and mitigating memory corruption attack vectors. The vulnerability's low-risk classification does not diminish the importance of applying the patch, as memory corruption issues can often serve as entry points for more sophisticated attacks when combined with other vulnerabilities in the system.