CVE-2023-33669 in AC8
Summary
by MITRE • 06/02/2023
Tenda AC8V4.0-V16.03.34.06 was discovered to contain a stack overflow via the timeZone parameter in the sub_44db3c function.
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Analysis
by VulDB Data Team • 01/08/2025
The vulnerability identified as CVE-2023-33669 represents a critical stack overflow condition within the Tenda AC8V4.0-V16.03.34.06 router firmware. This issue manifests through the timeZone parameter processing within the sub_44db3c function, creating a potential pathway for remote code execution and system compromise. The affected device operates under a web-based management interface that fails to properly validate input parameters before processing them through the vulnerable function, allowing malicious actors to craft specially crafted requests that can overwrite stack memory contents. The stack overflow vulnerability stems from improper bounds checking and input sanitization mechanisms that should have prevented excessive data from being copied into fixed-size stack buffers. This flaw aligns with CWE-121, which describes stack-based buffer overflow conditions where insufficient bounds checking allows data to overwrite adjacent memory locations, potentially including return addresses and control data. The vulnerability is particularly concerning as it affects network infrastructure devices that are often deployed in residential and enterprise environments without regular security updates, creating persistent exposure windows for attackers.
The technical exploitation of this vulnerability requires an attacker to send a malformed HTTP request containing an excessively long timeZone parameter value to the affected router's web management interface. When the sub_44db3c function processes this parameter, it fails to validate the input length against the allocated buffer size, resulting in memory corruption that can be leveraged to overwrite the stack frame and potentially redirect execution flow. The attack vector is classified as remote and requires no authentication, making it particularly dangerous as it can be exploited by attackers who are not physically present at the target location. The implementation of the vulnerable function suggests poor defensive programming practices where input validation occurs too late in the processing pipeline, allowing malicious data to traverse multiple layers before causing the overflow condition. This vulnerability demonstrates weaknesses in the firmware's defensive coding practices and highlights the importance of input validation at all levels of software execution, particularly in network-facing components that handle user-provided data.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as successful exploitation can lead to complete system compromise and unauthorized access to network resources. Attackers who successfully exploit this vulnerability can gain arbitrary code execution privileges on the affected router, potentially enabling them to modify network configurations, redirect traffic, install malware, or use the device as a pivot point for further attacks within the local network. The router's role as a network gateway makes it an attractive target for attackers seeking persistent access to enterprise or residential networks, as compromising the device provides a stable foothold for extended reconnaissance and lateral movement activities. The vulnerability's presence in firmware versions that are commonly deployed and often remain unpatched creates a significant risk profile, particularly in environments where network device management is not properly maintained or where automatic update mechanisms are disabled. Network defenders must consider this vulnerability as part of broader security assessments, especially in environments where network infrastructure devices are not regularly updated or monitored for known security issues.
Mitigation strategies for CVE-2023-33669 should focus on immediate firmware updates from Tenda, which would contain patches addressing the buffer overflow condition in the sub_44db3c function. Organizations should implement network segmentation and access controls to limit exposure of affected devices to untrusted networks, while also considering temporary network isolation of devices until patches can be deployed. Network monitoring solutions should be configured to detect unusual traffic patterns that might indicate exploitation attempts, particularly focusing on malformed HTTP requests containing unusually long parameter values. The vulnerability underscores the importance of implementing robust input validation mechanisms at all levels of application code, including the use of secure coding practices that prevent buffer overflows through proper bounds checking and memory management. Additionally, network administrators should establish comprehensive device inventory management processes to identify all affected devices within their networks and implement regular security assessments to detect similar vulnerabilities in other network infrastructure components. The ATT&CK framework classification for this vulnerability would include techniques related to exploitation of remote services and privilege escalation, emphasizing the need for layered defensive strategies that address both the immediate vulnerability and broader network security posture.