CVE-2004-2680 in mod_python
Summary
by MITRE
mod_python (libapache2-mod-python) 3.1.4 and earlier does not properly handle when output filters process more than 16384 bytes, which can cause filter.read to return portions of previously freed memory.
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Analysis
by VulDB Data Team • 07/30/2019
The vulnerability identified as CVE-2004-2680 affects mod_python versions 3.1.4 and earlier, specifically within the libapache2-mod-python package that integrates Python scripting capabilities into the Apache web server. This issue stems from improper memory management handling within the output filter processing mechanism, creating a critical security flaw that can lead to memory corruption and potential code execution. The vulnerability manifests when output filters encounter data streams exceeding 16384 bytes in length, a common threshold in many web applications processing large content or file uploads. The flaw represents a classic buffer management error that can be exploited by malicious actors to manipulate memory contents and potentially execute arbitrary code on affected systems.
The technical root cause of this vulnerability lies in how mod_python handles memory allocation and deallocation during output filter processing operations. When filter.read operations process data larger than the 16384-byte threshold, the module fails to properly manage the memory regions that have been freed, resulting in situations where subsequent read operations may return data from previously deallocated memory segments. This memory reuse pattern creates a scenario where attackers can potentially access stale data, manipulate program execution flow, or extract sensitive information from memory. The vulnerability directly corresponds to CWE-125, which describes out-of-bounds read conditions, and CWE-416, which covers use after free conditions, both of which are fundamental memory safety issues that have plagued software systems for decades. The issue demonstrates poor memory management practices that violate standard security principles for memory allocation and deallocation.
The operational impact of CVE-2004-2680 extends beyond simple memory corruption, as it can enable attackers to perform sophisticated exploitation techniques that leverage the use after free vulnerability. An attacker could potentially craft malicious content that, when processed through the affected mod_python module, would trigger the memory corruption condition and allow for remote code execution. This vulnerability is particularly dangerous in web server environments where mod_python is used to handle dynamic content generation, file uploads, or API endpoints that process user-supplied data. The exploitation potential aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as successful exploitation could enable attackers to execute arbitrary commands on the compromised server. The vulnerability affects systems running Apache web servers with mod_python installed, making it relevant to a wide range of enterprise and web application environments that rely on Python scripting capabilities for dynamic content generation.
Mitigation strategies for this vulnerability require immediate patching of affected mod_python installations to versions that properly handle memory management for large data streams. System administrators should prioritize updating to mod_python 3.1.5 or later, which contains the necessary fixes for the memory handling issues. Additionally, implementing proper input validation and limiting the size of data processed through output filters can serve as temporary defensive measures while patches are deployed. Network segmentation and access controls should be enforced to limit exposure of affected systems, and monitoring should be implemented to detect potential exploitation attempts. The fix addresses the core memory management flaw by ensuring proper handling of memory regions during filter.read operations and implementing correct deallocation procedures that prevent the reuse of freed memory blocks. Organizations should also consider implementing runtime protections such as address space layout randomization and stack canaries to make exploitation more difficult even if the underlying vulnerability is not fully patched.