CVE-2021-44391 in RLC-410W
Summary
by MITRE • 01/29/2022
A denial of service vulnerability exists in the cgiserver.cgi JSON command parser functionality of reolink RLC-410W v3.0.0.136_20121102. A specially-crafted HTTP request can lead to a reboot. GetEnc param is not object. An attacker can send an HTTP request to trigger this vulnerability.
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Analysis
by VulDB Data Team • 02/02/2022
The CVE-2021-44391 vulnerability represents a critical denial of service weakness in the Reolink RLC-410W security camera firmware version 3.0.0.136_20121102. This flaw resides within the cgiserver.cgi component's JSON command parser functionality, which processes incoming HTTP requests containing encoded parameters. The vulnerability specifically manifests when the system encounters a malformed GetEnc parameter that deviates from expected object structure, creating a condition where the device's processing logic fails catastrophically. The root cause stems from inadequate input validation and error handling within the JSON parsing routine, allowing malformed data to propagate through the system's command processing pipeline.
The technical exploitation of this vulnerability occurs through a carefully crafted HTTP request that targets the cgiserver.cgi endpoint with a malformed GetEnc parameter value. When the camera's firmware attempts to parse this parameter as a JSON object without proper validation, it triggers an unexpected execution path that results in system instability. The parser's failure to properly handle the malformed input causes the device to enter a state where it automatically reboots, effectively rendering the security camera non-operational for the duration of the reboot cycle. This behavior aligns with CWE-129, which addresses improper validation of input length or value, and CWE-704, concerning incorrect type conversion or parsing of input data. The vulnerability demonstrates poor defensive programming practices where the system does not adequately sanitize or validate external inputs before processing them as structured data.
The operational impact of CVE-2021-44391 extends beyond simple service disruption, as it fundamentally compromises the availability of security monitoring capabilities. Organizations relying on the Reolink RLC-410W for surveillance purposes face potential security gaps during the device's reboot cycle, which could last several minutes. This denial of service condition creates windows of vulnerability where physical security monitoring is temporarily disabled, potentially allowing unauthorized access to protected areas. The attack vector requires minimal technical expertise and can be executed remotely, making it particularly dangerous for network-connected devices. From an adversarial perspective, this vulnerability maps to ATT&CK technique T1499.004, which involves network disruption through service availability attacks, and T1566.001, covering spearphishing through social engineering. The vulnerability's remote exploitability means that attackers can target multiple devices simultaneously without requiring physical access, amplifying the potential impact across deployed surveillance networks.
Mitigation strategies for CVE-2021-44391 should focus on both immediate defensive measures and long-term architectural improvements. Organizations must first apply firmware updates from Reolink when available, as the vulnerability is likely addressed in subsequent releases. Network segmentation and access control measures should be implemented to limit exposure of affected devices to untrusted networks, while monitoring systems should be deployed to detect anomalous HTTP request patterns that may indicate exploitation attempts. The device should be configured to disable unnecessary network services and features, reducing the attack surface available to potential attackers. Additionally, implementing intrusion detection systems that can identify malformed JSON requests targeting the cgiserver.cgi endpoint will provide early warning capabilities. Regular security assessments of networked devices should include verification of firmware versions and patch status to prevent similar vulnerabilities from persisting. The vulnerability highlights the importance of robust input validation and error handling in embedded systems, particularly those handling JSON data, and underscores the need for security-by-design principles in IoT device development. Organizations should also consider implementing redundant monitoring solutions to maintain security coverage during potential device reboots.