CVE-2009-2281 in MapServer
Summary
by MITRE
Multiple heap-based buffer underflows in the readPostBody function in cgiutil.c in mapserv in MapServer 4.x through 4.10.4 and 5.x before 5.4.2 allow remote attackers to execute arbitrary code via (1) a crafted Content-Length HTTP header or (2) a large HTTP request, related to an integer overflow that triggers a heap-based buffer overflow. NOTE: this issue reportedly exists because of an incomplete fix for CVE-2009-0840.
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Analysis
by VulDB Data Team • 08/24/2021
The vulnerability described in CVE-2009-2281 represents a critical heap-based buffer underflow affecting MapServer's cgiutil.c component within the mapserv application. This flaw exists in MapServer versions 4.x through 4.10.4 and 5.x before 5.4.2, making it a long-standing issue that impacted a significant portion of the software's user base. The vulnerability stems from improper handling of HTTP request data during the readPostBody function execution, creating conditions where attacker-controlled input can manipulate memory allocation and buffer boundaries.
The technical implementation of this vulnerability involves two primary attack vectors that exploit different aspects of the same underlying flaw. The first vector utilizes a crafted Content-Length HTTP header that, when processed by the vulnerable function, triggers an integer overflow condition. This integer overflow subsequently leads to heap-based buffer underflows that can be leveraged for arbitrary code execution. The second vector involves sending large HTTP requests that overwhelm the memory allocation mechanisms, creating similar buffer manipulation conditions. Both attack methods exploit the same fundamental flaw in how MapServer processes HTTP request bodies, making the vulnerability particularly dangerous as it can be triggered through multiple entry points.
From an operational perspective, this vulnerability presents a severe risk to systems running affected MapServer versions as it allows remote attackers to execute arbitrary code on vulnerable systems without requiring authentication. The heap-based buffer underflow creates opportunities for attackers to manipulate memory contents, potentially leading to privilege escalation, denial of service, or complete system compromise. The integer overflow component specifically targets the memory management routines, making it particularly effective in bypassing modern memory protection mechanisms such as stack canaries and address space layout randomization. This vulnerability directly maps to CWE-121 heap-based buffer overflow and CWE-190 integer overflow conditions, representing a classic example of how integer arithmetic errors can lead to memory corruption vulnerabilities.
The impact of this vulnerability extends beyond simple code execution as it represents a fundamental flaw in the input validation and memory management processes within MapServer's web interface handling. Attackers can exploit this vulnerability to gain unauthorized access to systems hosting MapServer applications, potentially compromising sensitive geographic information systems and mapping services. The incomplete fix referenced in the vulnerability description suggests that previous attempts to address similar issues in CVE-2009-0840 were insufficient, leaving the system vulnerable to related attack vectors. This pattern of incomplete remediation is common in complex software systems and demonstrates the challenges of addressing memory corruption vulnerabilities in legacy codebases.
Mitigation strategies for CVE-2009-2281 should focus on immediate version upgrades to MapServer 5.4.2 or later, which contain the proper fixes for both the integer overflow and buffer underflow conditions. Organizations should also implement network-level protections such as web application firewalls that can detect and block suspicious Content-Length headers and unusually large HTTP requests. Additional defensive measures include implementing strict input validation for HTTP headers, limiting request size thresholds, and monitoring for anomalous patterns in request processing that may indicate exploitation attempts. From an ATT&CK framework perspective, this vulnerability maps to techniques involving command and control communications and privilege escalation through code injection, making it a critical concern for organizations maintaining mapping and geographic information systems.