CVE-2012-2147 in munin
Summary
by MITRE
munin-cgi-graph in Munin 2.0 rc4 allows remote attackers to cause a denial of service (disk or memory consumption) via many image requests with large values in the (1) size_x or (2) size_y parameters.
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Analysis
by VulDB Data Team • 02/20/2019
The vulnerability identified as CVE-2012-2147 affects munin-cgi-graph component within Munin monitoring software version 2.0 rc4, representing a significant denial of service weakness that can be exploited remotely by attackers to consume excessive system resources. This flaw resides in the parameter validation mechanism of the CGI graph generation functionality, specifically targeting the size_x and size_y parameters that control image dimensions. The vulnerability enables malicious actors to submit multiple image requests with exceptionally large dimension values, leading to resource exhaustion that can incapacitate the monitoring system. The affected system components include both disk space and memory allocation mechanisms that are not properly constrained during image rendering operations. This weakness directly impacts the availability aspect of the system by creating conditions where legitimate users cannot access monitoring services due to resource depletion caused by the malicious requests.
The technical implementation of this vulnerability stems from inadequate input validation within the munin-cgi-graph component, which fails to impose reasonable limits on the size_x and size_y parameters. When attackers submit requests with exaggerated values for these parameters, the system attempts to generate images of enormous dimensions, causing exponential resource consumption. The flaw operates through a classic resource exhaustion attack pattern where the attacker leverages the system's lack of parameter bounds checking to consume available memory and disk space. The vulnerability is particularly dangerous because it can be exploited through simple HTTP requests without requiring authentication or specialized privileges, making it accessible to any remote attacker. The system's failure to implement proper input sanitization and parameter validation creates an attack surface that allows malicious users to manipulate the image generation process beyond acceptable operational limits.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the entire monitoring infrastructure. When exploited successfully, the denial of service condition can cause the system to consume all available memory, leading to system crashes or severe performance degradation that prevents legitimate monitoring activities. Disk space exhaustion represents another critical concern as the system generates increasingly large image files that can fill storage volumes within minutes of attack initiation. Network monitoring systems relying on Munin for data collection and visualization become vulnerable to this attack, potentially masking actual security incidents or system failures. The vulnerability affects both the availability and integrity of the monitoring service, as attackers can effectively render the system unusable while potentially creating persistent resource consumption issues that may require manual intervention to resolve. Organizations using this monitoring software face significant risk of operational disruption and potential data loss during sustained attacks.
Mitigation strategies for CVE-2012-2147 should focus on implementing strict parameter validation and resource limiting mechanisms within the munin-cgi-graph component. The most effective approach involves establishing reasonable upper bounds for size_x and size_y parameters, typically constrained to prevent generation of images exceeding standard display dimensions. Network-level protections such as rate limiting and request filtering can help prevent abuse of the vulnerability by limiting the number of requests from individual sources. System administrators should also implement monitoring for unusual resource consumption patterns that could indicate exploitation attempts. The implementation of input sanitization and parameter validation aligns with security best practices outlined in the CWE catalog under category 134 which addresses improper control of generation of code. Additionally, this vulnerability relates to ATT&CK technique T1499.004 which covers network denial of service attacks, and T1499.001 which addresses network denial of service through resource exhaustion. Organizations should consider upgrading to patched versions of Munin software and implementing proper access controls to limit exposure to this vulnerability. Regular security audits of monitoring infrastructure should include verification of parameter validation mechanisms and resource usage controls to prevent similar vulnerabilities from being exploited in other components.