Flag Forge is a Capture The Flag (CTF) platform. Recently, a high-severity Regular Expression Denial of Service (ReDoS) vulnerability was discovered in versions 2.3.2 and below. This vulnerability arises from the user profile API endpoint (/api/user/[username]), where the application constructs a regular expression dynamically using unescaped user input (the username parameter).
The CVSS score for this vulnerability is 7.5, classified as high severity. The potential risk to organizations includes service disruption, as attackers may leverage this vulnerability to consume excessive CPU resources, leading to Denial of Service for other users.
As of now, there are no known exploits available, and the vulnerability is not included in the Known Exploited Vulnerabilities (KEV) catalog. However, organizations should prioritize patching this vulnerability, as it poses a significant risk to operational integrity.
The fix is available in version 2.3.3 of Flag Forge. Organizations using affected versions should implement a Web Application Firewall (WAF) rule to block requests containing regex meta-characters in the URL path as a temporary workaround.
Organizations should address this vulnerability in their priority patch cycle to ensure service availability and protect against potential disruptions.
Vulnerability Details
The vulnerability allows attackers to exploit the user profile API endpoint by sending specially crafted usernames that contain regex meta-characters. This results in the MongoDB regex engine consuming excessive CPU resources.
The vulnerability is classified as CWE-1333, indicating an issue with regular expression denial of service.
The CVSS score of 7.5 indicates a high severity level, with an attack vector of NETWORK and a low attack complexity. Importantly, no privileges are required, and no user interaction is necessary for the exploit to be successful.
Technical Analysis
The root cause of this vulnerability lies in the dynamic construction of regular expressions using unescaped user input. When an attacker submits a username that exploits the regex engine's limitations, the application may experience excessive CPU usage.
The attack vector is classified as network-based, as the exploit can be executed remotely by sending crafted requests to the API endpoint. The attack complexity is low, allowing for easier exploitation without special conditions.
Since no privileges are required and user interaction is not necessary, this vulnerability poses a significant risk to any organization using affected versions.
The impact on availability is high, as the application can become unresponsive due to resource exhaustion caused by the malicious input.
Risk & Impact Analysis
The real-world deployment risk associated with this vulnerability is substantial. Organizations utilizing Flag Forge must consider the potential for service disruptions, which can affect user experience and trust.
The blast radius of this vulnerability is broad, as it can impact all users of the platform if exploited successfully. Organizations must assess their exposure and prioritize remediation efforts accordingly.
Given the CVSS score of 7.5 and the lack of known exploits, organizations should address this vulnerability in their priority patch cycle. The urgency is high due to the potential for significant downtime.
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
Flag Forge versions 2.3.2 and earlier are affected by this vulnerability. Organizations using these versions should upgrade to version 2.3.3 or later to mitigate the risk.
Mitigation & Remediation
To remediate this vulnerability, organizations should update to Flag Forge version 2.3.3 or later. In addition, implementing a Web Application Firewall (WAF) rule to block requests containing regex meta-characters in the URL path can serve as a temporary workaround until the upgrade is completed.
For further assistance, organizations may consider utilizing services such as penetration testing to identify similar weaknesses.
Detection Guidance
Organizations should monitor application logs for indicators of abnormal user activity, especially requests made to the user profile API endpoint. Additionally, monitoring CPU utilization trends may provide insights into potential exploitation attempts.
AppSecure Threat Intelligence Insight
The long-term significance of this vulnerability highlights the need for consistent security practices in software development, particularly concerning user input handling. Organizations should implement robust validation mechanisms to prevent similar vulnerabilities.
This incident represents a broader trend of vulnerabilities arising from improper handling of user input. Organizations should remain vigilant and proactive in identifying and addressing such weaknesses.
For additional resources, organizations can refer to our blog articles on web application penetration testing and API penetration testing best practices for further guidance.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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