CVE-2003-0842 in mod_gzip
Summary
by MITRE
Stack-based buffer overflow in mod_gzip_printf for mod_gzip 1.3.26.1a and earlier, and possibly later official versions, when running in debug mode, allows remote attackers to execute arbitrary code via a long filename in a GET request with an "Accept-Encoding: gzip" header.
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Analysis
by VulDB Data Team • 11/27/2024
The vulnerability identified as CVE-2003-0842 represents a critical stack-based buffer overflow in the mod_gzip module for apache web servers. This flaw affects versions 1.3.26.1a and earlier, with potential implications for later official releases as well. The vulnerability specifically manifests when the mod_gzip module operates in debug mode, creating a dangerous condition where remote attackers can exploit the software's handling of input data. The attack vector involves sending a specially crafted GET request that includes an "Accept-Encoding: gzip" header combined with an excessively long filename parameter. This combination triggers the buffer overflow condition in the mod_gzip_printf function, which is responsible for formatting output strings within the module's debug functionality.
The technical implementation of this vulnerability stems from improper bounds checking within the mod_gzip module's string handling routines. When the module processes incoming requests in debug mode, it fails to validate the length of filename parameters before copying them into fixed-size stack buffers. This classic buffer overflow scenario occurs because the code does not perform adequate input validation or length checking before performing string operations. The CWE-121 classification applies here as the vulnerability involves stack-based buffer overflow conditions where insufficient space is allocated for data being copied. The flaw demonstrates poor memory management practices and inadequate defensive programming techniques that have become standard industry concerns over the past two decades.
From an operational perspective, this vulnerability presents a severe threat to web server security as it allows remote code execution without requiring authentication or prior access to the system. Attackers can leverage this flaw to execute arbitrary code on vulnerable servers, potentially gaining complete control over the web hosting environment. The impact extends beyond simple privilege escalation as compromised servers can serve as launch points for further attacks within network infrastructures. The vulnerability affects the availability and integrity of web services since successful exploitation can lead to complete system compromise, data exfiltration, or service disruption. Organizations running affected versions of mod_gzip in debug mode face immediate security risks that could be exploited by automated scanning tools or determined attackers.
The mitigation strategies for this vulnerability involve several approaches that align with established security practices and frameworks. The primary recommendation is to immediately upgrade to a patched version of mod_gzip that addresses the buffer overflow condition. Organizations should also consider disabling debug mode in production environments where possible, as this eliminates the attack surface associated with the vulnerable code paths. Additionally, implementing proper input validation and length checking mechanisms within web server configurations can provide defense-in-depth measures. Network segmentation and intrusion detection systems can help detect exploitation attempts, while regular security assessments and vulnerability scanning should be conducted to identify similar issues in other components of the web infrastructure. The ATT&CK framework's T1059.007 technique for command and scripting interpreter execution applies to this vulnerability as exploitation results in arbitrary code execution capabilities that attackers can leverage for further system compromise.