CVE-2016-6558 in RP-AC52
Summary
by MITRE
A command injection vulnerability exists in apply.cgi on the ASUS RP-AC52 access point, firmware version 1.0.1.1s and possibly earlier, web interface specifically in the action_script parameter. The action_script parameter specifies a script to be executed if the action_mode parameter does not contain a valid state. If the input provided by action_script does not match one of the hard coded options, then it will be executed as the argument of either a system() or an eval() call allowing arbitrary commands to be executed.
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Analysis
by VulDB Data Team • 12/27/2024
The CVE-2016-6558 vulnerability represents a critical command injection flaw in ASUS RP-AC52 access point firmware versions 1.0.1.1s and earlier. This vulnerability resides within the apply.cgi web interface component and specifically targets the action_script parameter handling mechanism. The flaw occurs when the system processes user-supplied input through the action_script parameter without proper validation or sanitization, creating an avenue for malicious actors to execute arbitrary commands on the affected device. The vulnerability stems from the device's failure to properly validate input against a whitelist of acceptable values, instead allowing direct execution of user-provided commands through system() or eval() functions.
The technical implementation of this vulnerability demonstrates a classic command injection pattern where the firmware fails to implement proper input validation controls. When the action_mode parameter does not contain a valid state, the system falls back to executing the action_script parameter directly, bypassing normal security controls. This design flaw enables attackers to inject malicious commands that get executed with the privileges of the web application process, which typically runs with elevated permissions on network devices. The vulnerability is particularly dangerous because it operates at the web interface level, allowing remote exploitation without requiring physical access to the device. According to CWE-77, this maps directly to command injection weaknesses where untrusted data is incorporated into system commands without proper sanitization.
The operational impact of CVE-2016-6558 extends beyond simple command execution, as it provides attackers with complete control over the affected access point. An attacker could leverage this vulnerability to gain persistent access to the network, redirect traffic, install backdoors, or use the device as a pivot point for attacking other systems within the network. The remote nature of the exploit means that attackers can compromise these devices from anywhere on the internet, making them particularly attractive targets for cybercriminals. The vulnerability affects not just individual devices but entire network infrastructures, as compromised access points can serve as entry points for broader network infiltration. This aligns with ATT&CK technique T1059.007 for command and scripting interpreter, specifically targeting network devices and routers.
Mitigation strategies for CVE-2016-6558 should focus on immediate firmware updates from ASUS to address the underlying command injection flaw. Network administrators must ensure that all affected devices are updated to firmware versions that properly validate and sanitize input parameters before execution. Additionally, implementing network segmentation and access controls can limit the potential impact of exploitation, while monitoring for unusual network traffic patterns may help detect compromise attempts. The vulnerability highlights the importance of secure coding practices in embedded systems, particularly around input validation and privilege separation. Organizations should also consider implementing network access control lists to restrict access to administrative interfaces and regularly audit network device configurations to identify similar vulnerabilities across their infrastructure.