CVE-2009-2108 in Git
Summary
by MITRE
git-daemon in git 1.4.4.5 through 1.6.3 allows remote attackers to cause a denial of service (infinite loop and CPU consumption) via a request containing extra unrecognized arguments.
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Analysis
by VulDB Data Team • 12/04/2024
The vulnerability identified as CVE-2009-2108 affects the git-daemon component within git versions ranging from 1.4.4.5 through 1.6.3. This issue represents a classic denial of service weakness that can be exploited by remote attackers to disrupt the normal operation of git services. The git-daemon serves as a network service that allows clients to access git repositories over the network using the git protocol, making it a critical component in distributed version control systems. When an attacker sends a malformed request containing extra unrecognized arguments to the git-daemon, the service enters an infinite loop that consumes excessive CPU resources, effectively rendering the service unavailable to legitimate users.
The technical flaw stems from inadequate input validation and argument parsing within the git-daemon implementation. When processing client requests, the daemon fails to properly handle or reject unrecognized command-line arguments that are appended to the standard git protocol requests. This parsing failure causes the daemon to enter a loop where it continuously processes these malformed arguments without proper termination conditions, leading to sustained high CPU utilization. The vulnerability specifically manifests when the daemon encounters arguments that it cannot interpret or process according to its expected protocol format, triggering the problematic execution path that results in resource exhaustion.
The operational impact of this vulnerability extends beyond simple service disruption, as it can affect organizations relying on git-daemon for repository access and collaboration. Attackers can exploit this weakness to consume system resources indefinitely, potentially causing cascading effects on server performance and availability. In environments where git-daemon serves as a core infrastructure component for code repositories, this vulnerability could lead to significant downtime and service unavailability for development teams. The infinite loop behavior means that even after the initial attack, the daemon may remain in a degraded state until manually restarted, compounding the operational impact on system administrators.
This vulnerability aligns with CWE-400, which categorizes the issue as an "Uncontrolled Resource Consumption" or "Resource Exhaustion" weakness. The flaw demonstrates characteristics of the CWE-674 principle where a process fails to properly handle unexpected inputs, leading to unbounded resource consumption. From an ATT&CK framework perspective, this vulnerability maps to the T1499.004 technique related to "Network Denial of Service" and potentially T1566.001 for "Phishing via Service" if attackers use it as part of a broader attack chain. Organizations should implement immediate mitigations including upgrading to patched versions of git, implementing network-level restrictions to limit access to git-daemon services, and deploying monitoring solutions to detect unusual CPU consumption patterns that may indicate exploitation attempts. The vulnerability underscores the importance of proper input validation and robust error handling in network services, particularly those handling external protocol requests.