CVE-2018-7162 in Node.js
Summary
by MITRE
All versions of Node.js 9.x and 10.x are vulnerable and the severity is HIGH. An attacker can cause a denial of service (DoS) by causing a node process which provides an http server supporting TLS server to crash. This can be accomplished by sending duplicate/unexpected messages during the handshake. This vulnerability has been addressed by updating the TLS implementation.
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Analysis
by VulDB Data Team • 02/19/2020
The vulnerability identified as CVE-2018-7162 represents a critical denial of service flaw affecting Node.js versions 9.x and 10.x, with a HIGH severity rating that underscores its potential impact on production systems. This weakness specifically targets the TLS implementation within the Node.js http server functionality, creating a pathway for malicious actors to disrupt service availability through carefully crafted network traffic. The vulnerability stems from insufficient validation of TLS handshake messages, allowing attackers to exploit the protocol's handling of duplicate or unexpected messages during the secure connection establishment process.
The technical flaw manifests when Node.js processes TLS handshake sequences containing malformed or duplicate messages that trigger an unexpected crash in the http server process. This occurs because the underlying TLS library implementation fails to properly validate the sequence and timing of handshake messages, particularly during the critical phase where the server and client negotiate secure communication parameters. The vulnerability exploits the absence of proper state machine validation within the TLS implementation, leading to memory corruption or stack overflow conditions that result in process termination. This flaw is particularly dangerous because it requires minimal network activity to trigger, making it an attractive vector for attackers seeking to disrupt services without extensive reconnaissance.
The operational impact of CVE-2018-7162 extends beyond simple service disruption, as it can affect any Node.js application serving HTTPS traffic or utilizing TLS connections. Systems running vulnerable versions may experience complete service unavailability, requiring manual intervention to restart processes and potentially resulting in extended downtime for applications serving critical business functions. The vulnerability's exploitation does not require authentication or elevated privileges, making it accessible to any network entity capable of establishing TCP connections to the affected server. Organizations relying on Node.js for web applications, API services, or backend systems face significant risk of operational disruption, particularly in environments where high availability is critical.
Mitigation strategies for this vulnerability center on immediate patching of affected Node.js installations to versions that include corrected TLS implementation. The fix addresses the core issue by implementing proper validation of TLS handshake messages and strengthening the state machine handling during connection establishment. Organizations should prioritize updating their Node.js deployments across all environments, including development, testing, and production systems, while monitoring for any residual impacts from the patch. Additionally, network-level protections such as rate limiting and connection filtering can provide temporary mitigation while updates are deployed, though these measures do not address the root cause. Security teams should also implement monitoring for unusual TLS handshake patterns and establish incident response procedures to quickly address any exploitation attempts, as the vulnerability aligns with attack patterns documented in the ATT&CK framework under the T1499 category for network denial of service. The fix demonstrates a proper approach to addressing CWE-129 vulnerabilities related to improper input validation in cryptographic protocols, emphasizing the importance of robust protocol implementation in server-side applications.