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Home » Hacking News » Cisco patches away

Cisco patches away

by Nikola Strahija on January 27th, 2006 Cisco Systems has issued patches in the last two days for vulnerabilities in IOS authorisation feature and for a weakness that enables a DDoS attack on certain VPN concentrators.

Internetwork Operating System flaw allows users employing the Tcl (Tool Command Language) exec shell to get around the Authentication, Authorization, and Accounting (AAA) command authorisation feature. Users who employed the Tcl exec shell could use that access to execute commands above their privilege level.

Second vulnerability problem worsened the first flaw. If a user on an affected system terminates the session without leaving the Tcl Shell mode (by using the tclquit command), that shell process remains active and attached to the virtual type terminal VTY or TTY line. When another authenticated user connects to that device over the same line, he has access to the unterminated Tcl Shell process and might be able to bypass the AAA command authorisation checking.

The vulnerability affects all Cisco products running Cisco IOS version 12.0T or later, if support for the Tcl functionality is enabled and the AAA command authorization feature is enabled as well.

The third security hole patched affects Cisco VPN 3000 series running software 4.7.0 through 4.7.2.A, and it allows a DDoS attack on an unpatched device. A malicious HTTP packet sent to one of those concentrators could cause it to reload, dropping users' connections.

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