CVE-2017-16031 in Socket.io
Summary
by MITRE
Socket.io is a realtime application framework that provides communication via websockets. Because socket.io 0.9.6 and earlier depends on `Math.random()` to create socket IDs, the IDs are predictable. An attacker is able to guess the socket ID and gain access to socket.io servers, potentially obtaining sensitive information.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 03/21/2023
The vulnerability identified as CVE-2017-16031 affects Socket.io versions 0.9.6 and earlier, presenting a critical security flaw that undermines the integrity of real-time application communication frameworks. Socket.io serves as a foundational component for building realtime applications using websockets, enabling bidirectional communication between clients and servers. This particular vulnerability stems from the framework's reliance on the Math.random() function for generating socket identifiers, creating a predictable pattern that adversaries can exploit to compromise system security.
The technical flaw resides in the deterministic nature of the Math.random() function implementation, which produces pseudorandom numbers that follow a predictable sequence when properly analyzed. When Socket.io generates socket IDs using this method, it creates a vulnerability where an attacker can calculate or guess valid socket identifiers based on observed patterns or timing information. This predictability fundamentally compromises the authentication mechanism of the framework, as socket IDs serve as identifiers for establishing and maintaining client connections to the server. The vulnerability operates at the application layer and can be classified under CWE-330 Use of Insufficiently Random Values, which specifically addresses weaknesses in cryptographic implementations that use inadequate randomness sources.
The operational impact of this vulnerability extends beyond simple information disclosure, as it allows attackers to potentially hijack active connections, impersonate legitimate clients, and access sensitive data flowing through the socket.io infrastructure. An attacker who successfully guesses a socket ID can establish unauthorized connections to the server, potentially gaining access to private channels, real-time data streams, and user communications. This risk becomes particularly severe in environments where socket.io is used for critical applications such as chat systems, real-time collaboration tools, financial transactions, or any service requiring secure client-server communication. The vulnerability can be exploited through passive observation of existing connections or through active probing techniques that analyze timing patterns to reverse engineer the random number generation sequence.
Mitigation strategies for CVE-2017-16031 require immediate version upgrades to Socket.io 1.0.0 or later, where the framework implements proper random number generation for socket ID creation. Organizations should also consider implementing additional security controls such as connection rate limiting, authentication mechanisms, and network segmentation to reduce the attack surface. The vulnerability aligns with ATT&CK technique T1071.004 Application Layer Protocol: DNS, as attackers may use DNS-based reconnaissance to identify and target vulnerable Socket.io implementations. Security teams should also implement monitoring solutions that detect unusual connection patterns or unauthorized access attempts, particularly focusing on socket ID generation and connection establishment behaviors. Regular security assessments and vulnerability scanning should include checks for outdated Socket.io versions to prevent exploitation of this and similar predictability-based vulnerabilities in real-time communication frameworks.