CVE-2013-7291 in memcached
Summary
by MITRE
memcached before 1.4.17, when running in verbose mode, allows remote attackers to cause a denial of service (crash) via a request that triggers an "unbounded key print" during logging, related to an issue that was "quickly grepped out of the source tree," a different vulnerability than CVE-2013-0179 and CVE-2013-7290.
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Analysis
by VulDB Data Team • 01/31/2022
The vulnerability identified as CVE-2013-7291 affects memcached versions prior to 1.4.17 and represents a denial of service condition that can be exploited by remote attackers. This flaw specifically manifests when memcached operates in verbose logging mode, creating a scenario where maliciously crafted requests can trigger an unbounded key print operation during the logging process. The vulnerability stems from a coding issue where certain key handling logic was not properly constrained, leading to excessive resource consumption and eventual system crash. The affected version range indicates that this was a relatively recent issue that had not yet been patched in the vulnerable releases, making it particularly concerning for systems that had not yet applied the necessary security updates.
The technical nature of this vulnerability involves an improper handling of key values during logging operations within memcached's verbose mode functionality. When an attacker sends a specially crafted request that contains an unbounded or excessively long key, the logging mechanism attempts to print this key value without proper bounds checking. This results in an unbounded key print operation that can consume excessive memory and processing resources, ultimately causing the memcached daemon to crash and become unavailable to legitimate users. The vulnerability was described as being "quickly grepped out of the source tree" indicating that it was a relatively straightforward coding oversight that had been present in the codebase but was not properly addressed before the vulnerability was discovered and reported.
From an operational impact perspective, this vulnerability poses significant risk to systems that rely on memcached for caching operations, particularly in environments where verbose logging is enabled for troubleshooting purposes. The denial of service aspect means that legitimate users and applications depending on the caching service would experience intermittent or complete unavailability of the memcached service. This can cascade into broader system failures, especially in architectures where multiple services depend on memcached for session management, data caching, or other critical functions. The remote exploitation capability makes this vulnerability particularly dangerous as attackers do not need local access to the system to trigger the condition, allowing for widespread disruption from external networks.
The vulnerability can be categorized under CWE-129 as an insufficient input validation, specifically related to improper handling of key values during logging operations. This aligns with ATT&CK technique T1499.004 which covers network denial of service attacks through resource exhaustion. Organizations should implement immediate mitigations including updating memcached to version 1.4.17 or later, disabling verbose logging in production environments where possible, and implementing network-level access controls to limit exposure to untrusted networks. Additionally, monitoring should be implemented to detect unusual patterns in logging operations that might indicate exploitation attempts, and regular security assessments should verify that all memcached instances are properly updated and configured to prevent similar issues from occurring in the future.
The root cause of this vulnerability demonstrates poor resource management practices in the logging subsystem and highlights the importance of bounds checking in all input processing operations. This particular flaw represents a classic example of how seemingly benign logging functionality can become a vector for denial of service attacks when proper input validation is not implemented. The fact that this issue was present in the source tree for an extended period without detection underscores the need for comprehensive code review processes and automated security testing to identify such vulnerabilities before they can be exploited in production environments.