CVE-2017-16137 in Debug Module
Summary
by MITRE
The debug module is vulnerable to regular expression denial of service when untrusted user input is passed into the o formatter. It takes around 50k characters to block for 2 seconds making this a low severity issue.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 03/21/2023
The debug module vulnerability identified as CVE-2017-16137 represents a significant security concern within Node.js applications that utilize the debug package for logging and debugging purposes. This vulnerability specifically targets the o formatter within the debug module, which processes untrusted user input through regular expression patterns that are susceptible to denial of service attacks. The flaw exists in how the module handles certain input patterns that trigger catastrophic backtracking in regular expressions, causing the system to consume excessive computational resources and potentially leading to application unresponsiveness or complete denial of service.
The technical implementation of this vulnerability stems from the debug module's use of regular expressions to format output when the o formatter is employed. When untrusted input containing specific patterns is passed to this formatter, the regular expression engine enters into a state of catastrophic backtracking where it attempts to match the input against the pattern through an exponential number of possible paths. This behavior is particularly dangerous because the attack can be executed with relatively small input sizes, with the vulnerability demonstrating that as few as 50,000 characters can cause a 2-second delay in processing, effectively creating a denial of service condition that impacts system availability and responsiveness.
From an operational perspective, this vulnerability poses a moderate risk to applications that rely on the debug module for logging or debugging operations, particularly those that process user input through debug statements. The low severity classification does not diminish its potential impact since attackers can exploit this vulnerability to consume system resources and cause service disruption without requiring elevated privileges or complex attack vectors. The vulnerability affects applications where user-supplied data might be logged through debug statements, making it particularly concerning for web applications that handle user input and utilize the debug module for diagnostic purposes.
The vulnerability aligns with CWE-400, which categorizes the issue as a Regular Expression Denial of Service (ReDoS) vulnerability, and demonstrates characteristics consistent with ATT&CK technique T1499.004, which involves network denial of service attacks. Organizations should implement mitigations including upgrading to patched versions of the debug module, sanitizing user input before processing, and implementing rate limiting or input validation mechanisms to prevent exploitation. Additionally, security teams should monitor applications for debug statements that process untrusted input and consider implementing automated scanning tools to identify vulnerable code patterns. The remediation approach should focus on both immediate patching of the debug module and long-term code review processes to prevent similar vulnerabilities in other components of the application stack.