CVE-2023-7095 in A7100RU
Summary
by MITRE • 12/25/2023
A vulnerability, which was classified as critical, has been found in Totolink A7100RU 7.4cu.2313_B20191024. Affected by this issue is the function main of the file /cgi-bin/cstecgi.cgi?action=login of the component HTTP POST Request Handler. The manipulation of the argument flag leads to buffer overflow. The attack may be launched remotely. The exploit has been disclosed to the public and may be used. VDB-248942 is the identifier assigned to this vulnerability.
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Analysis
by VulDB Data Team • 01/18/2024
The vulnerability identified as CVE-2023-7095 represents a critical buffer overflow flaw in the Totolink A7100RU router firmware version 7.4cu.2313_B20191024. This issue resides within the HTTP POST Request Handler component of the device's web interface, specifically in the main function of the /cgi-bin/cstecgi.cgi script. The vulnerability manifests when processing login requests through the action=login parameter, making it accessible through standard web-based exploitation techniques. The buffer overflow occurs due to improper validation of the flag argument, which allows an attacker to exceed the allocated buffer space and potentially overwrite adjacent memory regions. This type of vulnerability falls under CWE-121, which describes stack-based buffer overflow conditions, and represents a significant security risk for network devices that are accessible over the internet. The attack vector is remotely exploitable, meaning that an attacker does not require physical access to the device or local network presence to launch the attack. The public disclosure of the exploit code (VDB-248942) further amplifies the severity of this vulnerability, as it provides attackers with a ready-made tool for exploitation.
The operational impact of this buffer overflow vulnerability extends beyond simple denial of service conditions, as it can potentially enable arbitrary code execution on the affected router. When an attacker successfully exploits this vulnerability, they can manipulate the device's memory layout to redirect execution flow, potentially gaining unauthorized administrative access to the router's management interface. This access would allow attackers to modify network configurations, install malicious firmware, redirect traffic, or establish persistent backdoors within the network infrastructure. The implications are particularly severe for home and small office networks where these devices often serve as the primary gateway to the internet, making them attractive targets for attackers seeking to compromise entire network ecosystems. The vulnerability affects the authentication mechanism of the device, which means that successful exploitation could lead to complete compromise of the network's perimeter defenses.
Mitigation strategies for CVE-2023-7095 should prioritize immediate firmware updates from the vendor, although the specific nature of this vulnerability may require careful consideration of update procedures to avoid device bricking. Network administrators should implement additional security controls such as restricting access to the router's web interface through firewall rules, limiting access to trusted IP addresses, and disabling unnecessary services. The principle of least privilege should be applied by ensuring that only authorized personnel have access to the router's management interface. Security monitoring should include detection of unusual traffic patterns that might indicate exploitation attempts, particularly around the affected cgi-bin endpoint. Organizations should also consider implementing network segmentation to limit the potential impact of a successful exploitation, and regular vulnerability assessments should be conducted to identify similar issues in other network devices. This vulnerability aligns with ATT&CK technique T1072, which covers software deployment methods, and represents a critical threat to network infrastructure security. The combination of remote exploitability, public disclosure, and the potential for complete device compromise makes this vulnerability particularly dangerous in enterprise and home network environments where router security is often overlooked.