AnywhereUSB/5 1.80.00 Drivers Integer Overflow Risk: low. This advisory can be found here: http://www.safend.com/advisories/digi_anywhereusb5_intoverflow.txt I. BACKGROUND AnywhereUSB/5 provides five USB ports, which deliver the same Plug and Play user experience as onboard USB ports. Software drivers are loaded onto a host PC or server, enabling remote devices to communicate with the host, without changing existing application software. Peripheral devices can be centrally managed and monitored from a remote server or PC via an IP address. http://www.digi.com/products/usb/anywhereusb.jsp II. DESCRIPTION This low-risk vulnerability in AnywhereUSB/5 1.80.00 allows an attacker to forge an AnywhereUSB server, so that if a client connects to it, it can be hit with a denial of service attack. This integer overflow in version 1.80.00 of AnywhereUSB/5 drivers package distributed for Windows NT 4.0/2000/XP and 2003. could allow attackers to Bugcheck (BSOD) currently connected clients on demand, or any new client upon connection. The problem exists within the parsing of USB string descriptors. A malformed string descriptor that in its header specifies a size of 1 byte, will cause a memory copy loop to go behind allocated memory range. This will result in a Bugcheck (BSOD) within the client computer driver. III. ANALYSIS Successful exploitation allows an attacker to crash the client computer and cause a Bugcheck (BSOD) on demand. Exploitation is possible in two ways: by sending a specially crafted string descriptor to the client or by attaching a maliciously crafted USB device to the hub. IV. DETECTION Safend has confirmed that AnywhereUSB/5 drivers version 1.80.00 is vulnerable. It is suspected that earlier versions of AnywhereUSB/5 may also vulnerable. V. WORKAROUND Avoid plugging unknown USB devices into an AnywhereUSB/5 hub. Apply strict firewalls rules, to prevent clients from connecting to a malicious AnywhereUSB/5 server, which could in turn send the malformed string descriptor to the client via TCP/IP. VI. VENDOR RESPONSE SecuriTeam was asked to assist the researchers with contacting Digi International. Reported to vendor: 24th of July, 2006. Vendor response: 25th of July, 2006. Vendor's official response: "The AnywhereUSB product is used with commercial USB peripheral devices on dedicated point to point IP connections, almost always on non-public local area networks. The likelihood of any such USB device producing a USB descriptor corrupted in precisely this way is extremely unlikely. This error will be corrected in a future driver release." VII. CVE INFORMATION The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2006-4459 to this issue. VIII. CREDIT This vulnerability was discovered by Itzik Kotler, Safend. IX. About SecuriTeam's Assisted Disclosure Many researchers do not have the time, energy or inclination to deal with reporting a vulnerability to vendors. SecuriTeam is here to help. If you want us to handle the logistics of contacting and following up with the vendor, making sure the problem is fixed, contact: STAD (at) SecuriTeam (dot) com. [email concealed] Our end goal is Full Disclosure, preferably in coordination with the vendor, without exposing the researcher to unnecessary risk. We do not believe in hiding or selling vulnerabilities. Never had, never will. All credit will be properly attributed. If asked we can act as proxies, keeping your privacy and anonymity. X. LEGAL NOTICES 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. --- Safend is a leading provider of innovative endpoint security solutions that protect against corporate data leakage and penetration via physical and wireless ports. For more information, visit http://www.safend.com/.