From mmaiffret@eeye.com Fri Feb 27 14:15:57 2004 From: Marc Maiffret To: BUGTRAQ@securityfocus.com Date: Thu, 26 Feb 2004 18:35:32 -0800 Subject: EEYE: RealSecure/BlackICE Server Message Block (SMB) Processing Overflow RealSecure/BlackICE Server Message Block (SMB) Processing Overflow Release Date: February 26, 2004 Date Reported: February 18, 2004 Severity: High (Remote Code Execution) Vendor: Internet Security Systems Software Affected: RealSecure Network 7.0, XPU 20.15 through 22.9 Real Secure Server Sensor 7.0 XPU 20.16 through 22.9 Proventia A Series XPU 20.15 through 22.9 Proventia G Series XPU 22.3 through 22.9 Proventia M Series XPU 1.3 through 1.7 RealSecure Desktop 7.0 eba through ebh RealSecure Desktop 3.6 ebr through ecb RealSecure Guard 3.6 ebr through ecb RealSecure Sentry 3.6 ebr through ecb BlackICE PC Protection 3.6 cbr through ccb BlackICE Server Protection 3.6 cbr through ccb Description: The RealSecure and BlackICE product lines from Internet Security Systems offer host-based intrusion detection/prevention for large servers and home networks. By design, these products attempt to identify and block network attacks and intrusions. eEye Digital Security has discovered a critical vulnerability in both RealSecure and BlackICE. The vulnerability allows a remote attacker to reliably overwrite heap memory with user-controlled data and execute arbitrary code within the SYSTEM context. This attack will succeed with BlackICE using its most paranoid settings. This specific flaw exists within the component that handles the processing of Server Message Block (SMB) packets. By issuing an authentication request with a long username value, a direct heap overwrite is triggered, and reliable code execution is then possible. Technical Description: An IDS/IPS system, by its very nature, requires that every packet entering a system be parsed and dealt with accordingly. When BlackICE and RealSecure encounter an SMB packet, the packet is analyzed, processed and re-assembled. It is during this assembly phase that our custom data is passed to an insufficiently sized heap-based buffer. All processing is conducted before any authentication. To successfully replicate this vulnerability only one SMB packet is required. The client must issue an "SMB Session Setup AndX request". This SMB is used to "set up" a session previously established with the negotiate protocol. A primary function of this request is to perform a user login to a remote host. As neither RealSecure nor BlackICE require the state to be kept, no previous negotiation is required. To cause a reliable heap overwrite, the AccountName parameter should contain a string with a length of 300 bytes or greater. Please refer to the SNIA Common Internet File System Technical Reference (http://www.snia.org/tech_activities/CIFS/CIFS-TR-1p00_FINAL.pdf) for detailed information on the required packet structures. In the end, this vulnerability equates to a textbook heap overwrite vulnerability, and code execution is effortless. Protection: Retina Network Security Scanner has been updated to identify this vulnerability. Vendor Status: ISS have released patches for these issues. The patches are available at: http://www.iss.net/download/ Credit: Barnaby Jack Related Links: Retina Network Security Scanner - Free 15 Day Trial http://www.eeye.com/html/Products/Retina/index.html Greetings: Cathy, The Filthy Few (we'll make up for it in July), and, of course -- all of the eEye massive. Copyright (c) 1998-2004 eEye Digital Security Permission is hereby granted for the redistribution of this alert electronically. It is not to be edited in any way without express consent of eEye. If you wish to reprint the whole or any part of this alert in any other medium excluding electronic medium, please e-mail alert@eEye.com for permission. Disclaimer The information within this paper may change without notice. Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties with regard to this information. In no event shall the author be liable for any damages whatsoever arising out of or in connection with the use or spread of this information. Any use of this information is at the user's own risk. Feedback Please send suggestions, updates, and comments to: eEye Digital Security http://www.eEye.com info@eEye.com