CVE-2018-5768 in AC15
Summary
by MITRE
A remote, unauthenticated attacker can gain remote code execution on the the Tenda AC15 router with a specially crafted password parameter for the COOKIE header.
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Analysis
by VulDB Data Team • 01/15/2020
The CVE-2018-5768 vulnerability represents a critical remote code execution flaw in Tenda AC15 router firmware that exposes devices to unauthorized remote exploitation without requiring authentication. This vulnerability specifically targets the router's handling of the COOKIE header parameter during authentication processes, creating a pathway for attackers to inject and execute arbitrary code on the affected device. The flaw stems from improper input validation and sanitization within the router's web interface authentication mechanism, allowing malicious actors to manipulate the password parameter in the COOKIE header to achieve privileged code execution.
The technical implementation of this vulnerability involves a classic buffer overflow or injection attack vector where the router's authentication subsystem fails to properly validate or sanitize the password parameter embedded within the COOKIE header. When the router processes this malformed parameter, it executes the injected code with the privileges of the web server process, typically running with administrative privileges. This vulnerability is particularly dangerous because it requires no prior authentication credentials and can be exploited remotely over the network, making it highly attractive to threat actors seeking persistent access to network infrastructure. The attack vector operates at the application layer and can be initiated through standard HTTP requests containing crafted COOKIE headers, making it difficult to detect through conventional network monitoring.
The operational impact of CVE-2018-5768 extends beyond simple remote code execution, as it provides attackers with complete administrative control over the affected router. This compromised device can then serve as a pivot point for broader network infiltration, enabling attackers to perform man-in-the-middle attacks, redirect traffic, disable security features, or establish persistent backdoors. The vulnerability affects all Tenda AC15 routers running vulnerable firmware versions, potentially exposing thousands of devices to compromise. Network administrators face significant risk as these devices often serve as the primary gateway between internal networks and the internet, making them prime targets for attackers seeking to establish footholds in corporate or residential networks. The lack of authentication requirements means that attackers can exploit this vulnerability at scale without needing to enumerate valid credentials, significantly increasing the attack surface.
Mitigation strategies for CVE-2018-5768 should prioritize immediate firmware updates from Tenda, as the vendor has released patches addressing this specific vulnerability. Network segmentation and firewall rules can help limit the exposure of these devices to external threats, while implementing intrusion detection systems can help identify suspicious COOKIE header patterns. Organizations should also consider disabling unnecessary web management interfaces and implementing network access controls to prevent unauthorized access to router management functions. This vulnerability aligns with CWE-77 and CWE-94 categories related to command injection and code execution flaws, and maps to ATT&CK techniques such as T1059 for command and script injection. Regular security audits and network monitoring should include checks for vulnerable router firmware versions, with particular attention to devices that have not received security updates. The vulnerability underscores the importance of maintaining current firmware versions and implementing robust network security practices to prevent exploitation of similar authentication bypass flaws in network infrastructure devices.