Redhat Linux diskcheck.pl creates predictable temporary file and fails to check for existing symbolic link of same name

Overview

Diskcheck.pl is a PERL script, part of Red Hat’s powertools suite, that alerts a system administrator if any file system approaches capacity. In creating email alerts, diskcheck.pl creates insecure temporary files in a world-writable directory, which may permit an attacker to corrupt any writable file on the system.

Description

Diskcheck.pl is designed to run hourly. When any file system approaches capacity, it generates an email message to the system administrator, using a temporary file with a predictable name in the /tmp directory, without checking for the prior existence or ownership of this file. By its nature, Disckcheck runs with setuid root.

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Impact

By creating a symbolic link with appropriate name and pointed to any writable file on the system, a local attacker can corrupt that file when diskcheck detects a file system approaching capacity.

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Solution

Apply vendor patches; see the Systems Affected section below.

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Modify diskcheck.pl to remove any file from /tmp named for its temporary file.

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Vendor Information

570952

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RedHat __ Affected

Notified: December 05, 2000 Updated: October 04, 2001

Status

Affected

Vendor Statement

<http://www.linuxsecurity.com/advisories/redhat_advisory-955.html&gt;

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us [email](<mailto:[email protected]?Subject=VU%23570952 Feedback>).

CVSS Metrics

Group	Score	Vector
Base
Temporal
Environmental

References

• <http://www.securityfocus.com/bid/2050&gt;
• <http://www.linuxsecurity.com/advisories/redhat_advisory-955.html&gt;

Acknowledgements

This vulnerability was first announced by Stan Bubrouski .

This document was last modified by Tim Shimeall.

Other Information

CVE IDs:	CVE-2000-0715
Severity Metric:	4.32 Date Public: