There is a DoS vulnerability in Cisco Linksys router WRH54G http service. Any anonymous attacker could crash the http
service easily by sending a malformed http request, and needn't any privilege.
When the device attempts to process the malformed request, it will be possible to corrupt sensitive memory. Although
unconfirmed, it may also be possible to modify various configuration settings or execute malicious code.
After being attacked, Cisco Linksys router can't be accessed remotely by any user. Http service is not recovered and
the attacked router can not be managed without a hard reboot. A reboot of router may cause network disconnected.
Further more, the firewall can still route packets.
Affected products:
Cisco Linksys WRH54G and other devices
(bacause I have no enough other Linksys routers in hand, I can't make sure how many devices this vulnerability can
effect.)
Affected versions:
The lasted Firmware v1.01.03
If Need any privilege:
No
A malformed http request can cause the http service crashed. The malformed request is mixed by string ./ and overly
charactors. Its format is as follows:
Http://192.168.1.1/./front_page......front_page.asp
4.1 Make sure the router is running normally, and the Web server is right.
agefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_pagefront_page.asp
4.3 Check the http service, it can't work.
Note:
The string ./ in malformed request is necessary. Lack of this string, the http server will ask the anonymous to
input auth information.
the string .asp in the end of malformed request is also necessary. Lack of this string, we can not crash the http
server.
The firmware information could be found at:
http://www-cn.linksys.com/servlet/Satellite?childpagename=CN%2FLayout&packedargs=page%3D2%26cid%3D1140648553423%26c%3DL_Content_C1&pagename=Linksys%2FCommon%2FVisitorWrapper&SubmittedElement=Linksys%2FFormSubmit%2FProductDownloadSearch&sp_prodsku=1172713275887
There is another DoS vulnerability about malformed http request in Linksys
devices(http://www.securityfocus.com/bid/6301/info).
The description and explit are different from this vulnerability.