CVE-2021-42756 is a critical vulnerability affecting Fortinet's FortiWeb product across multiple versions. This vulnerability allows an unauthenticated remote attacker to execute arbitrary code by sending specially crafted HTTP requests. The severity of this vulnerability is underscored by its CVSS score of 9.8, classifying it as critical. The potential for exploitation is significant, as attackers can target unpatched systems directly over the network, leading to severe implications for confidentiality, integrity, and availability.
Risk to organizations includes unauthorized access and control over affected systems, which can lead to data breaches or service disruptions. Given the nature of the vulnerabilities and their exploitation potential, organizations are urged to take immediate action to mitigate associated risks.
The exploitation status of this vulnerability indicates that there are known exploits available, making it imperative for organizations to prioritize patching immediately. The urgency of addressing this vulnerability cannot be overstated, as failure to do so could result in catastrophic consequences.
Organizations leveraging Fortinet FortiWeb must ensure their systems are updated to mitigate this vulnerability effectively. This includes reviewing current configurations and applying vendor patches as soon as they are available.
Vulnerability Details
The vulnerability is classified as a stack-based buffer overflow (CWE-121) and is present in FortiWeb versions 5.x, 6.0.7 and below, 6.1.2 and below, 6.2.6 and below, 6.3.16 and below, and all versions of 6.4. The official description states that these vulnerabilities could allow an unauthenticated remote attacker to achieve arbitrary code execution via crafted HTTP requests.
The CVSS score of 9.8 indicates a high-severity security issue, with a critical level of risk. This score reflects the ease of exploitation (low complexity, no privileges required, no user interaction needed) and the severe impact on confidentiality, integrity, and availability.
The vulnerability was published on February 16, 2023, and continues to pose a significant threat to organizations using affected FortiWeb products.
Technical Analysis
The root cause of CVE-2021-42756 stems from improper handling of input within the proxy daemon of FortiWeb, leading to stack-based buffer overflow conditions. Attackers may exploit this vulnerability over the network, which requires low attack complexity and does not necessitate any privileges or user interaction.
The attack vector is network-based, enabling remote exploitation, which increases the urgency for remediation. The vulnerability's attack complexity is low, allowing even less skilled attackers to leverage it effectively. The impacts on confidentiality, integrity, and availability are all high, indicating that successful exploitation can lead to significant operational disruptions.
Risk & Impact Analysis
The real-world deployment risk associated with CVE-2021-42756 is substantial. Organizations that utilize Fortinet FortiWeb without immediate patching could face unauthorized access, data loss, and potential legal ramifications from data breaches. The blast radius for this vulnerability is extensive, given that many organizations rely on FortiWeb for web application security.
The urgency assessment is critical, as the CVSS score of 9.8 reflects a significant threat that must be addressed in priority patch cycles. Organizations should prioritize remediation actions to protect their assets and maintain compliance with industry regulations.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | Yes |
Public PoC | Yes |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The affected versions of FortiWeb are as follows: all versions of FortiWeb 5.x, 6.0.7 and below, 6.1.2 and below, 6.2.6 and below, 6.3.16 and below, and all versions of 6.4. Organizations should verify their systems against these versions to ensure compliance.
Mitigation & Remediation
Organizations are advised to patch their FortiWeb systems immediately. The vendor has released updates to address these vulnerabilities. Organizations should ensure they are running the latest version of FortiWeb to mitigate risks. For additional guidance, refer to the penetration testing to uncover any remaining vulnerabilities.
Detection Guidance
To detect potential exploitation of this vulnerability, organizations should monitor logs for unusual HTTP request patterns. Behavioral anomalies, such as unexpected spikes in traffic or access attempts to sensitive areas, should also be flagged. Additionally, network signatures that correlate with exploitation attempts should be established to enhance detection capabilities.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2021-42756 emphasizes the need for robust security practices in web application firewalls. This vulnerability represents a broader pattern of stack-based buffer overflow issues that can be exploited if left unaddressed. Security teams should take this as a lesson to regularly assess their configurations and patching processes to stay ahead of emerging threats. For further insights, consider exploring our vulnerability management program and the importance of continuous security assessments in maintaining a secure posture.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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