CVE-2021-22124 in FortiSandbox
Summary
by MITRE • 08/05/2021
An uncontrolled resource consumption (denial of service) vulnerability in the login modules of FortiSandbox 3.2.0 through 3.2.2, 3.1.0 through 3.1.4, and 3.0.0 through 3.0.6; and FortiAuthenticator before 6.0.6 may allow an unauthenticated attacker to bring the device into an unresponsive state via specifically-crafted long request parameters.
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Analysis
by VulDB Data Team • 08/08/2021
The vulnerability identified as CVE-2021-22124 represents a critical denial of service weakness affecting FortiSandbox and FortiAuthenticator products across multiple version ranges. This issue stems from inadequate input validation within the authentication modules where the system fails to properly handle excessively long request parameters. The flaw manifests when an unauthenticated attacker crafts malicious requests containing unusually long parameter values that cause the authentication service to consume excessive system resources, ultimately leading to device unresponsiveness and service disruption. The vulnerability impacts FortiSandbox versions 3.2.0 through 3.2.2, 3.1.0 through 3.1.4, and 3.0.0 through 3.0.6, alongside FortiAuthenticator versions prior to 6.0.6, creating a significant operational risk for organizations relying on these security appliances for network protection and user authentication services.
The technical implementation of this vulnerability involves the exploitation of resource consumption patterns within the login processing modules of affected Fortinet products. When the authentication service receives request parameters exceeding acceptable length thresholds, the system's processing logic fails to implement proper bounds checking or resource limiting mechanisms. This leads to a scenario where the authentication daemon consumes increasing amounts of memory and cpu cycles as it attempts to process these malformed requests. The flaw aligns with CWE-400, which categorizes uncontrolled resource consumption as a fundamental weakness in software design that can lead to denial of service conditions. The attack vector is particularly concerning as it requires no authentication credentials, making it accessible to any network entity capable of reaching the vulnerable device's authentication endpoints.
The operational impact of CVE-2021-22124 extends beyond simple service disruption to potentially compromise broader network security operations. Organizations utilizing affected FortiSandbox appliances may experience complete loss of sandboxing capabilities for malware analysis and threat detection, while FortiAuthenticator users could face complete authentication service outages affecting user access to network resources. The vulnerability creates a persistent risk where attackers can maintain service degradation through repeated exploitation attempts, potentially leading to extended downtime that impacts business operations and security monitoring capabilities. This weakness particularly affects environments where these appliances serve as critical components of identity management and security orchestration frameworks, as the denial of service can cascade into broader security infrastructure failures.
Mitigation strategies for this vulnerability should prioritize immediate patching of affected systems to the latest Fortinet firmware versions that contain the necessary code fixes. Organizations must implement network segmentation to limit direct access to authentication endpoints and deploy intrusion detection systems capable of identifying and blocking malformed request patterns. The implementation of rate limiting and request parameter length validation at network boundaries can provide additional defensive layers against exploitation attempts. Security teams should also conduct thorough vulnerability assessments to identify all instances of affected Fortinet appliances within their environments and establish monitoring protocols to detect potential exploitation attempts. The ATT&CK framework categorizes this vulnerability under T1499.004 for network denial of service attacks, making it essential for organizations to maintain comprehensive incident response procedures that address resource exhaustion vulnerabilities. Regular security assessments and network monitoring should be enhanced to detect anomalous authentication request patterns that could indicate exploitation attempts.