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ZeroG InstallAnywhere5 Symlink Vulnerability

06.20.03

BACKGROUND

InstallAnywhere is a software framework that simplifies software installation on multiple client and server platforms. InstallAnywhere is utilized by vendors such as LimeWire (http://www.limewire.org). More information about InstallAnywhere is available at http://www.zerog.com.

DESCRIPTION

Zero G Software Inc.'s InstallAnywhere applications insecurely creates temporary files without checking for symbolic links allowing a local attacker to possibly overwrite any system file.

During installation the following temporary files are created:

/tmp/persistent_state
/tmp/env.properties.NNNNN

Where NNNNN represents the process id of the installation program. During installation InstallAnywhere does not check for symbolic links before opening the temporary files. An attacker can overwrite arbitrary system files by creating a symbolic link from one of the temporary files and then waiting for the super-user (root) to launch the InstallAnywhere installer.

As an example consider if an attacker were to create a symbolic link from /tmp/persistent_state to /etc/passwd:

$ ln -s /etc/passwd /tmp/persistent_state

Upon installation of InstallAnywhere by a user with write permissions to /etc/passwd that file would be overwritten.

ANALYSIS

An attacker with local system access and write access to /tmp can exploit the above-described vulnerability to clobber an arbitrary file.

iDEFENSE has proof of concept exploit code demonstrating the impact of this vulnerability.

DETECTION

iDEFENSE has confirmed the existence of this vulnerability in InstallAnywhere Enterprise Edition 5.0.6 and 5.0.7. It is suspected that previous versions are vulnerable as well.

WORKAROUND

If possible when installing as root either boot into single user mode or temporarily remove group and other write permissions (chmod og-rwx /tmp) on the /tmp directory. Simply checking for the existence of exploiting symbolic links before installation is insufficient as a window of opportunity still exists for exploitation.

VENDOR RESPONSE

This issue has reportedly been addressed in the latest release of InstallAnywhere.

CVE INFORMATION

A Mitre Corp. Common Vulnerabilities and Exposures (CVE) number has not been assigned to this issue.

DISCLOSURE TIMELINE

02/27/2003   Exploit acquired by iDEFENSE
03/04/2003   Initial vendor notification
06/06/2003   iDEFENSE Clients notified
06/20/2003   Public Disclosure

CREDIT

This vulnerability is credited to Larry Cashdollar.

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LEGAL NOTICES

Copyright © 2004 Verisign, Inc.

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Disclaimer: The information in the advisory is believed to be accurate
at the time of publishing based on currently available information. Use
of the information constitutes acceptance for use in an AS IS condition.
There are no warranties with regard to this information. Neither the
author nor the publisher accepts any liability for any direct, indirect,
or consequential loss or damage arising from use of, or reliance on,
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