CVE-2017-16115 in timespan
Summary
by MITRE
The timespan module is vulnerable to regular expression denial of service. Given 50k characters of untrusted user input it will block the event loop for around 10 seconds.
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Analysis
by VulDB Data Team • 03/21/2023
The vulnerability identified as CVE-2017-16115 affects the timespan module, which is commonly used in node.js applications for parsing and manipulating date and time values. This module processes user input through regular expressions to interpret time spans and durations, creating a critical security risk that can be exploited through malicious input patterns. The vulnerability stems from the module's insufficient input validation and inefficient regular expression implementation that fails to handle malformed or specially crafted inputs appropriately.
The technical flaw manifests when the timespan module encounters untrusted user input exceeding 50,000 characters in length. Under these conditions, the regular expression engine becomes trapped in a computationally expensive backtracking operation that consumes excessive CPU resources and blocks the event loop for approximately ten seconds. This behavior represents a classic regular expression denial of service (ReDoS) vulnerability, where malicious input causes the regular expression engine to perform exponential time complexity operations. The vulnerability aligns with CWE-400, which specifically addresses unchecked resource consumption through regular expressions.
The operational impact of this vulnerability is significant for applications that process user-provided time span data, particularly web applications that accept date and time parameters from external sources. An attacker can exploit this weakness to perform denial of service attacks against the application, causing legitimate requests to be delayed or dropped entirely. The ten-second delay per request can be amplified through concurrent attacks, potentially leading to complete service unavailability. This vulnerability affects the availability aspect of the CIA triad and can be categorized under ATT&CK technique T1499.004, which covers network denial of service attacks.
Mitigation strategies for CVE-2017-16115 involve multiple layers of defense to protect against regular expression denial of service attacks. The primary recommendation is to upgrade to a patched version of the timespan module or replace it with a more secure alternative that properly validates input and implements timeouts for regular expression operations. Developers should implement input length restrictions and sanitize all user-provided time span data before processing. Additionally, employing regular expression engines that detect and prevent catastrophic backtracking patterns, such as those found in the regexpp library, can provide protection against similar vulnerabilities. Organizations should also consider implementing rate limiting and request timeout mechanisms to prevent exploitation of such vulnerabilities in production environments.