CVE-2024-43380 in fugit
Summary
by MITRE • 08/19/2024
fugit contains time tools for flor and the floraison group. The fugit "natural" parser, that turns "every wednesday at 5pm" into "0 17 * * 3", accepted any length of input and went on attempting to parse it, not returning promptly, as expected. The parse call could hold the thread with no end in sight. Fugit dependents that do not check (user) input length for plausibility are impacted. A fix was released in fugit 1.11.1.
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Analysis
by VulDB Data Team • 08/21/2024
The vulnerability identified as CVE-2024-43380 affects the fugit gem, a time parsing library used by flor and the floraison group for processing temporal expressions. This issue manifests in the "natural" parser component of fugit which translates human-readable time specifications such as "every wednesday at 5pm" into cron-style scheduling expressions like "0 17 3". The fundamental flaw lies in the parser's inability to handle excessively long input strings gracefully, creating a potential denial of service condition where the parsing operation becomes unresponsive and consumes system resources indefinitely.
The technical implementation of this vulnerability stems from the parser's lack of input validation and length constraints during the parsing process. When a malformed or excessively long input string is provided, the parser enters an infinite loop or extremely long-running process that does not return control to the calling thread. This behavior violates the expected operational characteristics of a parsing function that should complete within reasonable timeframes and return appropriate error responses for invalid inputs. The vulnerability represents a classic example of a resource exhaustion attack vector where malicious or malformed input can cause the application to hang indefinitely, consuming CPU cycles and thread resources without proper timeout or bounds checking.
The operational impact of this vulnerability extends to all applications and systems that depend on fugit for time parsing functionality, particularly those that accept user input without proper validation or length checking. Applications using fugit in web forms, API endpoints, or any user-facing interfaces where time specifications are processed become vulnerable to denial of service attacks. An attacker could exploit this by submitting extremely long time specification strings, causing the application to become unresponsive and potentially leading to system resource exhaustion. This vulnerability affects the availability aspect of the system's security posture, as legitimate users may be unable to access services while the parsing thread remains blocked indefinitely.
The fix implemented in fugit version 1.11.1 addresses this issue by introducing proper input length validation and timeout mechanisms within the natural parser. This remediation aligns with security best practices outlined in the CWE database under CWE-400, which addresses "Uncontrolled Resource Consumption" and specifically covers denial of service vulnerabilities arising from inadequate input validation. The solution demonstrates proper defensive programming techniques that prevent resource exhaustion attacks by establishing reasonable bounds on input processing. Organizations should prioritize updating their dependencies to fugit 1.11.1 or later versions to mitigate this vulnerability. The remediation also reflects principles from the MITRE ATT&CK framework's resource exhaustion tactics, where attackers may exploit parsing vulnerabilities to consume system resources and disrupt service availability. System administrators should monitor their applications for continued use of vulnerable versions and implement proper input sanitization measures as additional defense-in-depth strategies.