[VulnWatch] Mac OS X Arbitrary File Overwrite via Core Files
From: _at_stake Advisories (_at_stake)
Date: Tue, 28 Oct 2003 12:50:44 -0500 To: firstname.lastname@example.org
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Advisory Name: Arbitrary File Overwrite via Core Files
Release Date: 10/24/2003
Platform: Mac OS X
Author: Dave G. <email@example.com>
Vendor Status: Vendor has new release with fix
CVE Candidate: CAN-2003-0877
In the event a system is running with core files enabled,
attackers with interactive shell access can overwrite arbitrary
files, and read core files created by root owned processes. This
may result in sensitive information like authentication credentials
Core file creation is disabled by default in Mac OS X. In the event
that core files are enabled on an Mac OS X system, root owned
processes will write a core file to the /cores directory. The name
of the core file will be: core.PID(*). This file will be owned by
root, and is set with 0400 permissions (read only for root, no
privileges for anyone else).
(*) PID would be the process ID of the process that dumped core
Since the /cores directory is world writable and core file names are
predictable, an attacker with interactive shell access can create
symbolic links in this directory, pointing them to files that exist
elsewhere on the file system. Through this mechanism, we can
overwrite files by symbolically linking to them.
At this point, an attacker can overwrite any file with the contents
of a core file. In order to read the core files, one can make a
symbolic link to a file on a mounted DMG image. Any user can mount
a disk image, allowing them to effectively 'steal' core files.
Depending on what was in the memory of the process that dumped core,
an attacker may be able to find out private information, including
This is fixed in Mac OS X 10.3. The core files setting is off by
default on all shipping versions of Mac OS X. For further information
on Mac OS X 10.3, please see http://www.apple.com/macosx/
1) Upgrade to Panther (Mac OS X 10.3).
2) If upgrading to Panther is not an option, ensure that core file
creation is disabled.
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-2003-0877 Arbitrary File Overwrite via Core Files
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Copyright 2003 @stake, Inc. All rights reserved.
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