Microsoft PPTP Service Buffer Overflow May Let Remote Users Execute Arbitrary Code
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SecurityTracker Alert ID: 1005296 |
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CVE Reference: GENERIC-MAP-NOMATCH
(Links to External Site)
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Date: Sep 26 2002
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Impact: Denial of service via network, Execution of arbitrary code via network, Root access via network
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Version(s): Windows 2000, XP
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Description: A buffer overflow vulnerability was reported in Microsoft's point-to-point protocol (PPTP) service. A remote user can cause the system to crash and may be able to execute arbitrary code.
phion Information Technologies issued a security advisory warning of a pre-authentication buffer overflow affecting both the PPTP
client and server implementation.
A remote user can send a specially crafted PPTP packet to overwrite kernel memory and crash
the system. It is also possible to overwrite the EDI and EDX registers and, according to the report, potentially execute arbitrary
shell code.
The vendor has reportedly been notified.
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Impact: A remote user can cause the system to crash. A remote user may be able to execute arbitrary code on the system.
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Solution: No solution was available at the time of this entry.
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Vendor URL: www.microsoft.com/technet/security/ (Links to External Site)
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Cause: Boundary error
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Underlying OS: Windows (2000), Windows (XP)
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Underlying OS: Windows (2000), Windows (XP)
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Reported By: sh@phion.com
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Message History:
This archive entry has one or more follow-up message(s) listed below.
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Source Message Contents
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Date: Thu, 26 Sep 2002 12:43:46 +0300
From: sh@phion.com
Subject: Microsoft PPTP Server and Client remote vulnerability
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phion Security Advisory 26/09/2002
Microsoft PPTP Server and Client remote vulnerability
Summary
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The Microsoft PPTP Service shipping with Windows 2000 and XP contains a
remotely exploitable pre-authentication bufferoverflow.
Affected Systems
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Microsoft Windows 2000 and XP running either a PPTP Server or Client.
Impact
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With a specially crafted PPTP packet it is possible to overwrite kernel
memory.
A DoS resulting in a lockup of the machine has been verified on
Windows 2000 SP3 and Windows XP.
A remote compromise should be possible deploying proper shellcode,
as we were able to fill EDI and EDX with our data.
Clients are vulnerable too, because the Service always listens on port
1723 on any interface of the machine, this might be of special concern
to DSL users which use PPTP to connect to their modem.
Solution
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As a temporary solution for the Client issue, one might firewall the PPTP
port in the Internet Connection Firewall for Windows XP.
We dont know of any solution for Windows 2000 and Windows XP PPTP servers.
The vendor has been informed.
Acknowledgements
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The bug has been discovered by Stephan Hoffmann and Thomas Unterleitner
on behalf of phion Information Technologies.
Contact Information
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phion Information Technologies can be reached via:
office@phion.com / http://www.phion.com
Stephan Hoffmann can be reached via:
sh@phion.com
Thomas Unterleitner can be reached via:
t.unterleitner@phion.com
References
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[1] phion Information Technologies
http://www.phion.com/
Exploit
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phion Information Technologies will not provide an exploit for this issue.
Disclaimer
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This advisory does not claim to be complete or to be usable for any
purpose.
This advisory is free for open distribution in unmodified form.
Articles or Publications that are based on information from this advisory
have to include link [1].
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