Title: Cisco Context Based Access Control Protocol Check Bypassing Vulnerability
Severity: MODERATE
Description:
IOS is a Cisco Internetwork Operating System. It is maintained and distributed by Cisco, and used on various types of Cisco hardware.
A problem with IOS makes it possible for a remote user to access protected systems through a vulnerable firewall. The problem is in the checking of protocol types.
Context Based Access Control is the stateful firewall implementation used with Cisco IOS software. When a system inside the protected network initiates a connection with a system outside of the network, a state entry of the connection is made in a table on the firewall system. This state entry records the connecting and receiving host, as well as the port numbers.
The problem is in the checking of protocol. The vulnerable version of IOS does not check the protocol type of the packets, thus making it possible for a system on either end of the connection to send data of a different type. One such instance would be a system on the protected network sending a UDP packet to a system outside of the protected network, and the external system returning a connection to the host via TCP using the pre-established IP address and port numbers.
This could allow a remote user to gather intelligence about a host, and potentially lead to an organized attack against network resources.
Affected Products:
- Cisco IOS 11.2P
- Cisco IOS 11.3T
- Cisco IOS 12.0T
- Cisco IOS 12.0XA
- Cisco IOS 12.0XB
- Cisco IOS 12.0XC
- Cisco IOS 12.0XD
- Cisco IOS 12.0XE
- Cisco IOS 12.0XG
- Cisco IOS 12.0XI
- Cisco IOS 12.0XK
- Cisco IOS 12.0XM
- Cisco IOS 12.0XQ
- Cisco IOS 12.0XR
- Cisco IOS 12.0XV
- Cisco IOS 12.1
- Cisco IOS 12.1E
- Cisco IOS 12.1T
- Cisco IOS 12.1XB
- Cisco IOS 12.1XC
- Cisco IOS 12.1XF
- Cisco IOS 12.1XG
- Cisco IOS 12.1XH
- Cisco IOS 12.1XI
- Cisco IOS 12.1XJ
- Cisco IOS 12.1XK
- Cisco IOS 12.1XL
- Cisco IOS 12.1XM
- Cisco IOS 12.1XP
- Cisco IOS 12.1XT
- Cisco IOS 12.1YB
- Cisco IOS 12.1YC
- Cisco IOS 12.1YE
- Cisco IOS 12.1YF
- Cisco IOS 12.2
- Cisco IOS 12.2DD
- Cisco IOS 12.2T
- Cisco IOS 12.2XD
- Cisco IOS 12.2XE
- Cisco IOS 12.2XH
- Cisco IOS 12.2XI
- Cisco IOS 12.2XJ
- Cisco IOS 12.2XK
- Cisco IOS 12.2XQ
References:
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