CVE-2013-7205 in Nagios
Summary
by MITRE
Off-by-one error in the process_cgivars function in contrib/daemonchk.c in Nagios Core 3.5.1, 4.0.2, and earlier allows remote authenticated users to obtain sensitive information from process memory or cause a denial of service (crash) via a long string in the last key value in the variable list, which triggers a heap-based buffer over-read.
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Analysis
by VulDB Data Team • 01/31/2022
The vulnerability identified as CVE-2013-7205 represents a critical security flaw within Nagios Core monitoring software versions 3.5.1 and 4.0.2, and earlier releases. This issue resides in the process_cgivars function located within the contrib/daemonchk.c file, which serves as a component responsible for processing CGI variables in the web interface. The flaw manifests as an off-by-one error, a common class of programming vulnerability that occurs when a program manipulates array indices or string lengths with one too many or too few, leading to memory access violations that can compromise system integrity.
The technical exploitation of this vulnerability requires an authenticated attacker to manipulate CGI variable inputs, specifically targeting the last key-value pair in a variable list with an excessively long string. When this malformed input is processed, the function fails to properly validate the string length against allocated buffer boundaries, resulting in a heap-based buffer over-read condition. This memory access violation can potentially expose sensitive information from adjacent memory locations, including credentials, system paths, or other confidential data stored in the process memory space. The vulnerability's classification as heap-based indicates that the memory corruption occurs in the heap allocation area rather than on the stack, making it particularly challenging to detect and exploit consistently.
From an operational impact perspective, this vulnerability presents dual threats to system security and availability. The primary concern involves information disclosure, where attackers can extract sensitive data from memory through the buffer over-read condition, potentially leading to credential compromise or system reconnaissance. Additionally, the vulnerability can be leveraged for denial of service attacks, causing the Nagios daemon to crash and terminate unexpectedly, thereby disrupting critical monitoring services that organizations rely upon for system health tracking and incident response. The combination of these impacts makes this vulnerability particularly dangerous in production environments where continuous monitoring is essential for operational security.
Mitigation strategies for CVE-2013-7205 should prioritize immediate software updates to versions that contain the patched process_cgivars function with proper bounds checking and input validation. Organizations should implement network segmentation to limit access to Nagios web interfaces to authorized personnel only, reducing the attack surface for authenticated exploitation attempts. Input sanitization measures should be enhanced at the application level to validate all CGI variable lengths before processing, with specific attention to boundary conditions that could trigger the off-by-one error. The vulnerability aligns with CWE-121, heap-based buffer overflow, and can be mapped to ATT&CK technique T1059 for command and scripting interpreter usage, as attackers may leverage this vulnerability to gain unauthorized access to monitoring systems and potentially escalate privileges within the network infrastructure.
The remediation process requires comprehensive testing of patched versions to ensure that the fix does not introduce regressions in legitimate functionality while maintaining the integrity of the monitoring service. Security teams should conduct regular vulnerability assessments to identify similar off-by-one errors in other components of the monitoring stack and establish robust input validation frameworks that prevent similar memory corruption vulnerabilities from emerging in future software releases. Organizations should also implement monitoring for unusual patterns in CGI request processing that might indicate exploitation attempts targeting this class of vulnerability, ensuring that security measures remain effective against evolving attack vectors in the threat landscape.