CVE-2016-10518 in ws Module
Summary
by MITRE
A vulnerability was found in the ping functionality of the ws module before 1.0.0 which allowed clients to allocate memory by sending a ping frame. The ping functionality by default responds with a pong frame and the previously given payload of the ping frame. This is exactly what you expect, but internally ws always transforms all data that we need to send to a Buffer instance and that is where the vulnerability existed. ws didn't do any checks for the type of data it was sending. With buffers in node when you allocate it when a number instead of a string it will allocate the amount of bytes.
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Analysis
by VulDB Data Team • 03/17/2023
The vulnerability identified as CVE-2016-10518 resides within the ws module, a popular WebSocket implementation for Node.js applications. This flaw specifically impacts versions prior to 1.0.0 and stems from improper handling of data types during the ping/pong frame processing mechanism. The ws module, which implements the WebSocket protocol, automatically responds to ping frames with corresponding pong frames containing the original payload data. While this behavior appears normal and expected, the underlying implementation contains a critical design flaw that allows for arbitrary memory allocation through crafted ping frames. The vulnerability manifests when the module internally converts all outgoing data to Buffer instances without validating the data type being processed.
The technical exploitation occurs because Node.js Buffers exhibit specific behavior when instantiated with numeric values instead of strings or arrays. When a Buffer is created with a number as its argument, it allocates memory space equal to that numeric value in bytes rather than treating it as character data. This fundamental characteristic of Node.js Buffer construction becomes the attack vector when the ws module fails to validate incoming data types before processing them for transmission. The vulnerability operates at the boundary between application logic and system memory management, where unvalidated user input flows directly into memory allocation routines without proper sanitization or type checking.
The operational impact of this vulnerability extends beyond simple resource exhaustion, representing a potential denial of service condition that could be exploited by remote attackers. An attacker capable of sending malicious ping frames could cause the targeted application to allocate massive amounts of memory, potentially leading to system instability, application crashes, or resource exhaustion that affects other services running on the same system. The vulnerability's severity is amplified by its accessibility through standard WebSocket communication channels, making it exploitable by anyone with network access to the affected service. This issue directly aligns with CWE-129, which addresses improper validation of length parameters, and represents a classic example of how insufficient input validation can lead to memory allocation vulnerabilities.
Mitigation strategies for CVE-2016-10518 require immediate version updates to ws module versions 1.0.0 or later, where the vulnerability has been addressed through proper type validation and sanitization of data before Buffer construction. Organizations should also implement network-level controls such as rate limiting and connection throttling to limit the potential impact of exploitation attempts. Additionally, monitoring for unusual memory consumption patterns and implementing proper input validation at multiple layers of the application architecture can help detect and prevent exploitation attempts. The fix implemented in later versions typically involves adding explicit type checking before buffer allocation, ensuring that numeric values are properly converted to strings or handled according to WebSocket protocol specifications rather than allowing direct numeric values to trigger memory allocation. This vulnerability demonstrates the importance of proper data validation and type checking in network protocols, aligning with ATT&CK technique T1499.004 for resource exhaustion and T1059.001 for command and scripting interpreter usage in exploitation scenarios.