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CORE FORCE Kernel Buffer Overflow
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SUMMARY
<http://force.coresecurity.com/> CORE FORCE is "the first community
oriented security solution for personal computers that provides a
comprehensive endpoint security solution for Windows 2000 and Windows XP
systems".
CORE FORCE provides inbound and outbound stateful packet filtering for
TCP/IP protocols using a Windows port of OpenBSD's PF firewall, granular
file system and registry access control and programs' integrity
validation. These capabilities can be configured and enforced system-wide
or on a per-application basis for specific programs such as email readers,
Web browsers, media players, messaging software, etc. The security
framework provided by CORE FORCE is leveraged by a community of security
experts that share their security configurations for a growing list of
programs. These security profiles can be downloaded by any user of CORE
FORCE from the community Web site and they're also completely open so that
they can be peer-reviewed to minimize security hazards.
Locally exploitable kernel buffer overflow vulnerabilities and unproperly
validated input arguments have been found in CORE FORCE Firewall and
Registry modules. The vulnerabilities allow unprivileged logged on users
to crash the system (denial of service), and they also may lead to a
privilege escalation or even a local root exploit.
DETAILS
Vulnerable Systems:
* CORE FORCE version 0.95.167 and below
Immune Systems:
* CORE FORCE version 0.95.172
Technical Description / Proof of Concept Code
The firewall functionality of CORE FORCE is as a port of OpenBSD's PF
firewall implemented as an NDIS complaint kernel driver that mediates
communications between the Network card and the TCP/IP stack of the
operating system. Thus stateful, bi-directional firewalling rules can be
enforced independently of the Windows OS firewall capabilities and at a
deeper layer, closer to the wire. The kernel driver is accessible to a
user mode application via IOCTL functions.
There are 4 IOCTL functions on the firewall driver module that use input
received from userspace and do not validate the length of the input
buffers properly. By calling any of these IOCTLs from with properly
crafted arguments, an unprivileged user could trigger vulnerabilities in
the driver and cause a denial of service or potentially to execute
arbitrary code with elevated privileges.
Similarly other 7 SSDT hook handler functions on the driver that
intercepts the Registry access on Windows are vulnerable to input
validation errors.
All the vulnerabilities can be reproduced by running a combination of DC2
and BSODHook tools.
Step by step instructions:
- Get DC2.exe (Driver Path Verifier) from the latest Windows Driver Kit.
- Login as unprivileged user.
- Run "dc2 /hct /a".
- Get BSODHook.exe from Matousec [3].
- Click on "Load Driver" then click on "Find SSDT hooks" then "Add to
probe list" and then "GO".
Report Timeline
2007-11-04: Initial notification by independent researcher Sebastian
Gottschalk.
2007-11-05: Email acknowledging reception of the bug reports and
indicating that looking into the report would probably take Core more than
a week. Core requested details to reproduce a second type of bug related
to hooking of the SSDT.
2007-11-05: Email from Sebastian Gottschalk indicating that the BSODhook
from Matousec [3] could be used to reproduce the SSDT hooking problems.
2007-11-19: A fix is produced by the Core Force team. Core asks the
researcher whether he wants to be credited for the discovery in the
advisory.
2007-11-22: Sebastian Gottschalk accepts to be credited.
2007-11-28: Email sent to Sebastian Gottschalk indicating the Core found a
bug in the fix and will have to delay publication of a fixed version of
Core Force.
2007-11-29: New fix committed by the Core Force team.
2007-12-17: Other functions were also found vulnerable in the Registry
module.
2008-01-07: New fix committed by the Core Force team.
2008-01-17: CORE-2007-1119 advisory is published.
References
[1] CORE FORCE: <http://force.coresecurity.com/>
http://force.coresecurity.com/
[2] Driver testing: <http://blogs.msdn.com/ravig/default.aspx>
http://blogs.msdn.com/ravig/default.aspx
[3]
<http://www.matousec.com/projects/windows-personal-firewall-analysis/plague-in-security-software-drivers.php>
http://www.matousec.com/projects/windows-personal-firewall-analysis/plague-in-security-software-drivers.php
ADDITIONAL INFORMATION
The information has been provided by <mailto:advisories@coresecurity.com>
CORE Security Technologies Advisories.
The original article can be found at:
<http://www.coresecurity.com/?action=item&id=2025>
http://www.coresecurity.com/?action=item&id=2025
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