CVE-2019-11923 in Mcrouter
Summary
by MITRE
In Mcrouter prior to v0.41.0, the deprecated ASCII parser would allocate a buffer to a user-specified length with no maximum length enforced, allowing for resource exhaustion or denial of service.
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Analysis
by VulDB Data Team • 03/07/2024
The vulnerability identified as CVE-2019-11923 affects Mcrouter versions prior to v0.41.0 and specifically targets the deprecated ASCII parser implementation. This parser handles incoming ASCII protocol requests that are commonly used in memcached-compatible systems for communication between clients and servers. The flaw exists within the buffer allocation mechanism where the system accepts user-specified buffer lengths without implementing any upper bounds or validation checks, creating a potential avenue for malicious exploitation through resource exhaustion attacks.
The technical implementation of this vulnerability stems from inadequate input validation within the ASCII protocol parser component of Mcrouter. When processing incoming requests, the parser allocates memory buffers based on values provided by the client without enforcing maximum size limitations. This design flaw allows an attacker to specify arbitrarily large buffer sizes in protocol requests, potentially causing the system to allocate excessive memory resources. The absence of size constraints in buffer allocation directly violates fundamental security principles for memory management and input validation, making the system susceptible to denial of service conditions.
The operational impact of this vulnerability extends beyond simple resource exhaustion to encompass broader system stability and availability concerns. An attacker could exploit this weakness by sending carefully crafted protocol requests with extremely large buffer size parameters, leading to memory exhaustion that could cause the Mcrouter process to crash or become unresponsive. This type of denial of service attack could severely impact applications relying on Mcrouter for caching operations, potentially disrupting service availability for legitimate users and creating cascading effects throughout dependent systems. The vulnerability affects systems where Mcrouter serves as a caching layer, particularly in high-traffic environments where resource exhaustion could have significant business impact.
Mitigation strategies for CVE-2019-11923 should focus on immediate patching to version v0.41.0 or later, which includes proper buffer size validation and enforcement mechanisms. Organizations should also implement network-level controls such as rate limiting and connection pooling to reduce the impact of potential exploitation attempts. The vulnerability aligns with CWE-122, which addresses improper restriction of operations within a limited memory buffer, and represents a classic example of insufficient input validation that enables resource exhaustion attacks. From an ATT&CK framework perspective, this vulnerability maps to T1499.004, which covers network denial of service attacks, and T1070.004, covering indicator removal on host through deletion of logs. System administrators should also consider implementing monitoring and alerting for unusual memory consumption patterns that could indicate exploitation attempts, while conducting regular vulnerability assessments to identify similar issues in other components of their caching infrastructure.