CVE-2019-11938 in Java Facebook Thrift
Summary
by MITRE
Java Facebook Thrift servers would not error upon receiving messages declaring containers of sizes larger than the payload. As a result, malicious clients could send short messages which would result in a large memory allocation, potentially leading to denial of service. This issue affects Facebook Thrift prior to v2019.12.09.00.
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Analysis
by VulDB Data Team • 04/11/2024
The vulnerability identified as CVE-2019-11938 represents a critical memory allocation flaw within Facebook Thrift server implementations that operates at the protocol level of distributed system communication. This issue stems from inadequate validation of container size declarations within Thrift message structures, creating a scenario where malicious actors can exploit the protocol's trust-based processing model to manipulate memory allocation behavior. The vulnerability specifically targets Java implementations of Facebook Thrift servers, which are widely used in enterprise environments for building scalable distributed applications and microservices architectures. The flaw enables attackers to craft specially formatted messages that declare container sizes significantly larger than the actual payload data, exploiting the server's failure to validate these size declarations against the actual message content.
The technical implementation of this vulnerability resides in the protocol deserialization process where Thrift servers accept and process container size information without proper bounds checking or validation. When a Thrift server receives a message containing a container size declaration that exceeds the actual payload data, it typically allocates memory based on the declared size rather than the actual content size. This behavior creates a direct path for memory exhaustion attacks, as the server's memory allocation mechanism processes the oversized container declaration without verification. The vulnerability falls under CWE-129, which specifically addresses inadequate input validation, and more broadly relates to CWE-400, concerning unspecified resource exhaustion. The flaw operates at the application layer of the OSI model, specifically affecting the presentation and session layers where data serialization and deserialization occur, making it particularly dangerous in environments where Thrift is used for high-volume service communication.
The operational impact of CVE-2019-11938 extends beyond simple denial of service conditions to potentially compromise entire service availability and system stability within affected environments. Attackers can leverage this vulnerability to consume excessive memory resources, leading to system crashes, application hangs, or complete service outages that can affect business operations and customer access. The vulnerability is particularly concerning in cloud-native environments where Thrift servers may be exposed to untrusted network clients, as the attack can be executed with minimal resources and sophistication. The memory allocation behavior creates a resource exhaustion scenario that can cascade through system components, affecting not just the immediate Thrift server but potentially impacting other services running on the same infrastructure. This vulnerability aligns with ATT&CK technique T1499.004, which describes resource exhaustion attacks targeting memory resources, and demonstrates how protocol-level flaws can be exploited to achieve system-level disruption.
Mitigation strategies for CVE-2019-11938 require immediate implementation of protocol-level validation controls and server configuration updates to address the root cause of the vulnerability. Organizations should prioritize upgrading to Facebook Thrift version v2019.12.09.00 or later, which includes proper size validation mechanisms for container declarations. Additionally, implementing network-level controls such as rate limiting, message size restrictions, and connection throttling can provide defense-in-depth measures to prevent exploitation. System administrators should also consider implementing memory monitoring and alerting mechanisms to detect unusual memory allocation patterns that may indicate exploitation attempts. The fix implemented in the patched version addresses the core issue by enforcing strict validation of container size declarations against actual payload data, preventing the allocation of memory resources that exceed reasonable bounds. Security teams should conduct comprehensive vulnerability assessments to identify all systems utilizing affected Thrift versions and implement network segmentation to limit exposure to untrusted clients. The mitigation approach should also include regular security testing and code reviews to ensure that similar validation gaps are not present in other protocol implementations or custom Thrift extensions within the organization's infrastructure.