CVE-2018-3767 in memjs
Summary
by MITRE
`memjs` versions <= 1.1.0 allocates and stores buffers on typed input, resulting in DoS and uninitialized memory usage.
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Analysis
by VulDB Data Team • 02/25/2020
The CVE-2018-3767 vulnerability affects the memjs library version 1.1.0 and earlier, which is a javascript client for memcached. This flaw resides in how the library handles typed input during buffer allocation and storage operations. The vulnerability specifically manifests when the library processes user-supplied data that gets converted into typed arrays or buffer objects. The issue stems from inadequate input validation and sanitization mechanisms within the memjs implementation, leading to improper handling of memory allocation patterns. When maliciously crafted input is processed, the library allocates memory buffers without proper bounds checking, potentially causing memory exhaustion or access to uninitialized memory regions. This behavior creates a dangerous attack surface where adversaries can exploit the library's memory management to disrupt service availability or potentially access sensitive data from memory.
The technical exploitation of this vulnerability occurs through the manipulation of input parameters that are subsequently converted into typed arrays or buffer objects. When memjs processes these inputs, it fails to validate the size or content of the typed data before allocating memory buffers. This lack of input sanitization allows attackers to supply inputs that cause the library to allocate excessive memory or access memory regions that have not been properly initialized. The vulnerability is particularly concerning because it can lead to denial of service conditions where the application consuming the memjs library becomes unresponsive or crashes due to memory allocation failures. The uninitialized memory access aspect poses additional security risks as it may expose sensitive information that was previously stored in the memory locations.
From an operational perspective, this vulnerability impacts applications that rely on memjs for memcached communication, particularly those handling untrusted input from external sources. The DoS potential means that attackers can disrupt services by causing memory exhaustion, leading to application crashes or degraded performance. The uninitialized memory usage creates additional security concerns as it may leak sensitive data through memory disclosure vulnerabilities. Organizations using affected versions of memjs should be particularly concerned about applications handling user input, API endpoints, or any system where external data flows through the memjs library. The vulnerability affects both client-side applications and server-side systems that utilize memjs for caching operations, making it a widespread concern across various deployment scenarios.
Mitigation strategies for CVE-2018-3767 primarily involve upgrading to memjs version 1.1.1 or later, which contains the necessary fixes for buffer allocation and input validation. Organizations should also implement input validation at multiple layers of their applications to prevent malicious data from reaching the memjs library. Network segmentation and access controls can help limit the attack surface by restricting direct access to systems using vulnerable memjs versions. Additionally, monitoring and logging mechanisms should be enhanced to detect anomalous memory allocation patterns or unusual buffer usage that might indicate exploitation attempts. The vulnerability aligns with CWE-129, which addresses improper validation of array indices, and relates to ATT&CK technique T1499.1, which covers network denial of service attacks. Security teams should also consider implementing runtime application self-protection measures or using memory sanitization tools to detect and prevent exploitation of similar memory handling vulnerabilities in other components of their application stack.