MacOS X TruBlueEnvironment Buffer Overflow

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                            @stake, Inc.
                          www.atstake.com

                        Security Advisory

Advisory Name: TruBlueEnvironment Buffer Overflow
Release Date: 01/27/2004
Application: TruBlueEnvironment
Platform: Mac OS X 10.3.x and 10.2.x
Severity: A user with an account on the system can become root
Author: Dave G. <[email protected]>
Vendor Status: Notified, Patch Issued
CVE Candidate: CAN-2004-0089 TruBlueEnvironment Buffer Overflow
Reference: www.atstake.com/research/advisories/2004/a012704-1.txt

Overview:

TruBlueEnvironment is part of the MacOS Classic Emulator. It is
setuid root and installed by default. There is a buffer overflow
vulnerability that allows a user with interactive access to escalate
privileges to root.

Details:

TruBlueEnvironment takes the value of an environment variable and
copies it into a buffer without performing any bounds checking. Since
this buffer is stored on the stack, it is possible to overwrite the
return stack frame and execute arbitrary code as root.

Vendor Response:

This is fixed in Security Update 2004-01-26. Further information
about this update is available via:

http://docs.info.apple.com/article.html?artnum=61798

Recommendation:

Restrict access to the TruBlueEnvironment(*) executable, or remove
it entirely if it is not being used. One approach to restricting
access would be to remove global execute permissions from the
TruBlueEnvironment executable, and only allow a specific group to
execute the application. The following commands will restrict access
to the 'admin' group:

sudo chown .admin
/System/Library/CoreServices/Classic\
Startup.app/Contents/Resources/TruBlueEnvironment

sudo chmod 4750
/System/Library/CoreServices/Classic\
Startup.app/Contents/Resources/TruBlueEnvironment

(*) Located in
/System/Library/CoreServices/Classic\
Startup.app/Contents/Resources/TruBlueEnvironment

Common Vulnerabilities and Exposures (CVE) Information:

The Common Vulnerabilities and Exposures (CVE) project has assigned
the following names to these issues. These are candidates for
inclusion in the CVE list (http://cve.mitre.org), which standardizes
names for security problems.

CAN-2004-0089 TruBlueEnvironment Buffer Overflow

@stake Vulnerability Reporting Policy:
http://www.atstake.com/research/policy/

@stake Advisory Archive:
http://www.atstake.com/research/advisories/

PGP Key:
http://www.atstake.com/research/pgp_key.asc

Copyright 2004 @stake, Inc. All rights reserved.

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