Microsoft ActiveSync 4.x Weak Password Obfuscation

2007.10.16
Risk: Medium
Local: No
Remote: Yes
CWE: CWE-310


CVSS Base Score: 7.1/10
Impact Subscore: 6.9/10
Exploitability Subscore: 8.6/10
Exploit range: Remote
Attack complexity: Medium
Authentication: No required
Confidentiality impact: Complete
Integrity impact: None
Availability impact: None

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Symantec Vulnerability Research http://www.symantec.com/research Security Advisory Advisory ID: SYMSA-2007-010 Advisory Title: Microsoft ActiveSync 4.x Weak Password Obfuscation Author: Ollie Whitehouse / ollie_whitehouse (at) symantec (dot) com [email concealed] Release Date: 15-10-2006 Application: ActiveSync 4.x Platform: Microsoft Windows Severity: Information Disclosure Vendor status: Update available CVE Number: CVE-2007-5460 Reference: http://www.securityfocus.com/bid/25976 Overview: Microsoft ActiveSync 4.1 acts as the gateway between your Windows powered PC and Windows Mobile powered device, enabling the transfer of Outlook information, Office documents, pictures, music, videos and applications from your desktop to your device. A vulnerability has been discovered in the mechanism that Microsoft uses to obfuscate the password when it's sent over the USB network interface between the device and the host machine. This enables malicious software on the host to either impersonate a device in order to obtain the current password or, if in a position to sniff network traffic, obtain the password for trivial decoding. Details: When a device is docked via USB it uses the connection like a standard network interface. Once an IP address is obtained the device will initially communicate via RAPI with the host on port 990/TCP. It will go through a small handshake routine and then, if appropriate, challenge the host for the devices PIN or Password. When the user supplies this PIN/Password on the host it will be obfuscated via XOR with a fixed key of E9 and then sent over the USB network connection to the device for verification. This process results in two vulnerabilities. Firstly, should an attacker be in a position to sniff the host computer's network connection he will be able to recover the PIN/Password. Secondly, an attacker can spoof the docking process of the device in an attempt to get the user to supply his PIN/Password. If we take a sample packet: 0000 82 00 60 0f e8 00 80 00 60 0f e8 00 08 00 45 00 ..`..... `.....E. 0010 00 32 59 95 40 00 80 06 49 31 a9 fe 02 02 a9 fe .2Y. (at) . (dot) . [email concealed] I1...... 0020 02 01 03 de 05 d0 e8 c0 cb c0 56 2e 41 75 50 18 ........ ..V.AuP. 0030 fa 6a 91 dd 00 00 08 00 d8 e9 db e9 da e9 dd e9 .j...... ........ We can see that byte 36 is the length of the password (8 bytes) followed by a NULL. After which is the password obfuscated with E9, this is immediately apparent due to the use of a UNICODE string for the password so every second byte is 0x00 XOR 0xE9 which equals 0xE9. Vendor Response: There is a security vulnerability that could allow for Information Disclosure. An attacker would need to do one of two things, either tether a cable to the USB sync cable or bind a network sniffer to the USB-RNDIS interface - requiring administrative permissions on the workstation hosting the AS connection. Recommendation: Windows Mobile 5.0 Please see your handset manufacturer to obtain the update customized for your device. This issue is fixed in Windows Mobile 6. Common Vulnerabilities and Exposures (CVE) Information: The Common Vulnerabilities and Exposures (CVE) project has assigned the following names to these issues. These are candidates for inclusion in the CVE list (http://cve.mitre.org), which standardizes names for security problems. CVE-2007-5460 Requested - - -------Symantec Consulting Services Advisory Information------- For questions about this advisory, or to report an error: research (at) symantec (dot) com [email concealed] For details on Symantec's Vulnerability Reporting Policy: http://www.symantec.com/research/Symantec-Responsible-Disclosure.pdf Consulting Services Advisory Archive: http://www.symantec.com/research/ Symantec Vulnerability Research GPG Key: http://www.symantec.com/research/Symantec_Vulnerability_Research_GPG.asc - - -------------Symantec Product Advisory Information------------- To Report a Security Vulnerability in a Symantec Product: secure (at) symantec (dot) com [email concealed] For general information on Symantec's Product Vulnerability reporting and response: http://www.symantec.com/security/ Symantec Product Advisory Archive: http://www.symantec.com/avcenter/security/SymantecAdvisories.html Symantec Product Advisory PGP Key: http://www.symantec.com/security/Symantec-Vulnerability-Management-Key.a sc - - --------------------------------------------------------------- Copyright (c) 2007 by Symantec Corp. Permission to redistribute this alert electronically is granted as long as it is not edited in any way unless authorized by Symantec Consulting Services. Reprinting the whole or part of this alert in any medium other than electronically requires permission from research (at) symantec (dot) com. [email concealed] Disclaimer The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information. Symantec, Symantec products, and Symantec Consulting Services are registered trademarks of Symantec Corp. and/or affiliated companies in the United States and other countries. All other registered and unregistered trademarks represented in this document are the sole property of their respective companies/owners. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.7 (MingW32) iD8DBQFHE7Viuk7IIFI45IARAkxzAJ99akjWoHVMst4g/c8THG0b7KAfAQCgvW+3 HQclsou8+GstIMcuBfA3FGc= =UwdB -----END PGP SIGNATURE-----


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