CVE-2021-45993 in Tenda
Summary
by MITRE • 02/04/2022
Tenda routers G1 and G3 v15.11.0.17(9502)_CN were discovered to contain a stack overflow in the function formIPMacBindModify. This vulnerability allows attackers to cause a Denial of Service (DoS) via the IPMacBindRuleIP and IPMacBindRuleMac parameters.
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Analysis
by VulDB Data Team • 02/05/2022
The vulnerability identified as CVE-2021-45993 affects Tenda routers model G1 and G3 running firmware version v15.11.0.17(9502)_CN, representing a critical stack overflow condition within the formIPMacBindModify function. This flaw resides in the router's web interface handling mechanism where user-supplied parameters are processed without adequate input validation or bounds checking. The specific parameters IPMacBindRuleIP and IPMacBindRuleMac serve as entry points for exploitation, allowing remote attackers to manipulate the router's memory structure through malformed input sequences.
The technical implementation of this vulnerability stems from improper buffer management within the router's firmware codebase, specifically manifesting as a classic stack-based buffer overflow condition. When the formIPMacBindModify function processes the IPMacBindRuleIP and IPMacBindRuleMac parameters, it fails to validate the length of incoming data against the allocated buffer space. This oversight enables attackers to inject excessive data that overflows the stack frame, potentially corrupting adjacent memory locations and causing unpredictable behavior. The vulnerability operates at the application layer within the router's web server component, making it accessible through standard HTTP requests to the affected web interface.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as it represents a potential pathway for more sophisticated attacks within the context of router security. While the immediate effect manifests as a denial of service, the underlying stack corruption could theoretically be exploited to execute arbitrary code or escalate privileges within the router's operating environment. This vulnerability affects the availability and integrity of the network infrastructure, as unauthorized users could disrupt network services and potentially gain persistent access to the device's management interface. The attack vector requires no authentication, making it particularly dangerous as it can be exploited remotely by any attacker with network access to the router's web interface.
Mitigation strategies for CVE-2021-45993 should prioritize firmware updates from Tenda as the primary remediation approach, as the vulnerability exists within the device's core software implementation. Network administrators should implement network segmentation and access control measures to limit exposure of affected devices to untrusted networks, while also monitoring for suspicious traffic patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-121 Stack-based Buffer Overflow, which is categorized under the broader software weakness classification for buffer overflow conditions. From an adversarial perspective, this vulnerability could be classified within the MITRE ATT&CK framework under the Tactic of Execution and Persistence, potentially enabling attackers to establish footholds within network infrastructure. Organizations should also consider implementing intrusion detection systems capable of identifying malformed HTTP requests targeting the specific vulnerable parameters, while maintaining regular vulnerability assessments to identify similar issues in other network equipment.