It seems to be fairly well known that there are multiple unpatched CSRF vulnerabilities in the administration interfaces for various Linksys routers. Since the initial reports of these are from a few years ago, and since some exploits are available, I have written additional proof of concept exploits for the Linksys routers that I have access to. While in most cases the victim must be authenticated with the application in question to exploit a CSRF vulnerability, since the factory default passwords for all of the routers in question are known to be admin, the victim does not necessarily need to be authenticated. This means that only suggested workaround that I have seen up until now, do not surf the web wile authenticated in the router's administration interface, does not solve the problem in certain cases where the user is still using the default password. This is mitigated somewhat by the fact that most browsers provide at least some degree of protection from these types of attacks, described in additional detail below. In each case, the proof of concept will enable remote administration of the router on port 31337, while changing the password to __pwn3d__. WRT54G2 PoC (tested with hardware version 1.5 and firmware version 1.50):
The form's action can be changed in the following way to attempt to log in with the default password: As I mentioned before, success of this type of exploit depends on the victim's browser. This is simply blocked in IE8, while Safari will give a phishing warning, Firefox warns the user that they are attempting to log in with the name "a", and Google Chrome simply allows the request without notifying the user in any way. WRT54G PoC (tested with hardware version 6 and firmware version 1.02.8):
WRT54G CSRF PoC
To attempt a login with the default password, the same type of modification can be made, as shown here: BEFSR41 PoC (tested with hardware version 3 and firmware version 1.06.01): And once again, a modification can be made to attempt to log in with the default password, as shown here: It is worth mentioning that even if a user has changed the router's password, but is using a weak password, they may still be vulnerable to this type of attack. An attacker could simply try many weak passwords in a dictionary-style attack. They could also use javascript to attempt to brute force the password, provided that they were able to get the victim to stay on a page for a reasonably long time. -Martin Barbella