b0f has reported two vulnerabilities in various Linksys BEF series routers, which can be exploited to cause a DoS (Denial of Service).

1) An error within the administrative web interface when attempting to authenticate a user can be exploited to crash the router by passing overly long strings (about 150 bytes each) to the "sysPasswd" and "sysPasswdConfirm" parameters in "Gozila.cgi".

2) A similar error also within the administrative web interface can be exploited by passing an overly long string (about 350 bytes) to the "DomainName" parameter in "Gozila.cgi".

Successful exploitation crashes the network device. Reportedly, it also makes it impossible for an administrator to log in even after reboots and therefore requires a factory reset to regain proper functionality.

The vulnerabilities have been reported in the following products:
* Linksys BEFSR41 v1/v2 (firmware 1.45.7 and 1.44.2z and possibly prior)
* Linksys BEFSR41 v3
* Linksys BEFSRU31
* Linksys BEFSR11
* Linksys BEFSX41
* Linksys BEFSR81 v2/v3
* Linksys BEFW11S4 v3
* Linksys BEFW11S4 v4

Solution
Grant only access to the administrative web interface from dedicated management systems.
Further details available in Customer Area

Provided and/or discovered by
b0f

Deep Links
Links available in Customer Area