CVE-2023-40599 in Mailform Pro CGI
Summary
by MITRE • 08/25/2023
Regular expression Denial-of-Service (ReDoS) exists in multiple add-ons for Mailform Pro CGI 4.3.1.3 and earlier, which allows a remote unauthenticated attacker to cause a denial-of-service condition. Affected add-ons are as follows: call/call.js, prefcodeadv/search.cgi, estimate/estimate.js, search/search.js, suggest/suggest.js, and coupon/coupon.js.
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Analysis
by VulDB Data Team • 09/20/2023
Regular expression denial-of-service vulnerabilities represent a critical class of security flaws that can severely impact system availability and performance. The vulnerability identified in CVE-2023-40599 affects Mailform Pro CGI versions 4.3.1.3 and earlier, specifically targeting multiple add-ons within the application's ecosystem. This vulnerability falls under the CWE-400 category of Uncontrolled Resource Consumption, which encompasses various forms of resource exhaustion attacks that can compromise system stability and availability. The affected components include call/call.js, prefcodeadv/search.cgi, estimate/estimate.js, search/search.js, suggest/suggest.js, and coupon/coupon.js, all of which process user input through regular expression patterns that are susceptible to maliciously crafted inputs.
The technical flaw stems from the implementation of regular expressions in these JavaScript and CGI scripts that do not properly handle malicious input patterns designed to cause catastrophic backtracking. When an attacker submits carefully crafted input strings that match the vulnerable regular expression patterns, the regular expression engine enters into a state of exponential backtracking where it repeatedly attempts different matching paths, consuming increasing amounts of CPU time and memory resources. This behavior creates a condition where a relatively small input string can cause the application to consume excessive computational resources, leading to system slowdowns or complete service unavailability. The vulnerability is particularly dangerous because it can be exploited by unauthenticated remote attackers without requiring any special privileges or credentials, making it accessible to anyone who can interact with the affected web application.
The operational impact of this vulnerability extends beyond simple service disruption to potentially affect business continuity and user experience. When exploited, the ReDoS attack can cause the affected add-ons to become unresponsive, leading to failed form submissions, incomplete search results, and overall degraded application performance. In high-traffic environments, multiple concurrent attacks can quickly overwhelm system resources, resulting in complete denial of service for legitimate users. The vulnerability affects core functionality components within Mailform Pro CGI, meaning that critical business processes relying on these add-ons could be severely impacted. Organizations may experience increased support tickets, user frustration, and potential revenue loss due to service interruptions. Additionally, the vulnerability can serve as a precursor to more sophisticated attacks where attackers first establish a denial-of-service condition before attempting other exploitation techniques.
Mitigation strategies for CVE-2023-40599 should focus on both immediate remediation and long-term architectural improvements. The primary recommendation is to upgrade to Mailform Pro CGI version 4.3.1.4 or later, which contains patches specifically addressing the vulnerable regular expression patterns. Organizations should also implement input validation and sanitization measures to filter out potentially malicious patterns before they reach the regular expression processing logic. Network-level protections such as rate limiting and request filtering can help reduce the impact of ReDoS attacks by limiting the number of requests that can be processed within a given time period. Security teams should also consider implementing automated monitoring and alerting systems to detect unusual resource consumption patterns that may indicate ReDoS attacks. The ATT&CK framework categorizes this vulnerability under T1499.004 for Resource Exhaustion, emphasizing the importance of implementing proper resource management and monitoring controls. Organizations should also conduct regular security assessments to identify and remediate similar vulnerabilities in other applications and systems, as ReDoS attacks remain a prevalent threat in web application security.