AUSCERT External Security Bulletin Redistribution

                  ESB-2004.0167 -- eEye Security Bulletin
    RealSecure/BlackICE Server Message Block (SMB) Processing Overflow
                             27 February 2004


        AusCERT Security Bulletin Summary

Product:                BlackICE PC Protection 3.6 cbr to ccb
                        BlackICE Server Protection 3.6 cbr to ccb
                        RealSecure Network 7.0, XPU 20.15 to 22.9
                        Real Secure Server Sensor 7.0 XPU 20.16 to 22.9
                        Proventia A Series XPU 20.15 to 22.9
                        Proventia G Series XPU 22.3 to 22.9
                        Proventia M Series XPU 1.3 to 1.7
                        RealSecure Desktop 7.0 eba to ebh
                        RealSecure Desktop 3.6 ebr to ecb
                        RealSecure Guard 3.6 ebr to ecb
                        RealSecure Sentry 3.6 ebr to ecb
Publisher:              eEye Digital Security
Operating System:       Windows Server 2003
                        Windows XP
                        Windows 2000
                        Windows NT
                        Windows ME
                        Windows 98
Impact:                 Administrator Compromise
Access Required:        Remote

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RealSecure/BlackICE Server Message Block (SMB) Processing Overflow

Release Date:
February 26, 2004

Date Reported:
February 18, 2004

High (Remote Code Execution)

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

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.

Retina Network Security Scanner has been updated to identify this

Vendor Status:
ISS have released patches for these issues. The patches are available

Barnaby Jack

Related Links:
Retina Network Security Scanner - Free 15 Day Trial

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
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Please send suggestions, updates, and comments to:

eEye Digital Security

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