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CERT Coordination Center


Race condition in periodic

Vulnerability Note VU#626919

Original Release Date: 2000-11-13 | Last Revised: 2001-03-28

Overview

A race condition in the 'periodic' script allows local files to be overwritten. We believe that 'periodic' is typically used only with FreeBSD systems, though it may be installed on other systems.

Description

'periodic' is a script used in conjunction with cron to execute jobs at specified intervals. During ordinary work, periodic creates temporary files with predictable names of the form /tmp/periodic.$PID where $PID is the process identifier of the process running periodic. Because periodic is called by cron it runs with enhanced privileges. By polling the system for an executing instance of periodic, an intruder can exploit a race condition and create a symbolic link from /tmp/periodic.$PID to a file of the intruders choosing. The target file will be overwritten.

Impact

An attacker or intruder who has write access to the local file system and who can discover the PIDs of other processes (both capabilities are typical for ordinary local users) can overwrite any file
on the system regardless of the permissions on the file. This ability can be leveraged to gain root access in many circumstances.

Solution

Apply a patch from your vendor.

Vendor Information

626919
Expand all

FreeBSD

Notified:  November 02, 2000 Updated:  November 13, 2000

Status

  Vulnerable

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

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

Addendum

CERT/CC believes that the 'periodic' script is normally used only with FreeBSD.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Apple

Notified:  November 02, 2000 Updated:  November 13, 2000

Status

  Not Vulnerable

Vendor Statement

Mac OS X does not contain the 'periodic' application and is not vulnerable.

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.

BSDI

Notified:  November 02, 2000 Updated:  November 13, 2000

Status

  Not Vulnerable

Vendor Statement

No versions of BSD/OS are vulnerable to this problem. It does appear to be a problem with the new FreeBSD version and is not present in the original scripts that were part of 4.4BSD.

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.

Compaq Computer Corporation

Notified:  November 02, 2000 Updated:  November 13, 2000

Status

  Not Vulnerable

Vendor Statement

We don't use/ship with this.

Vendor Information

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

Addendum

CERT/CC believes that the 'periodic' script is normally used only with FreeBSD.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

IBM

Notified:  November 02, 2000 Updated:  January 10, 2001

Status

  Not Vulnerable

Vendor Statement

IBM's AIX operating system is not vulnerable to this exploit.

Vendor Information

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

Addendum

CERT/CC believes that the 'periodic' script is normally used only with FreeBSD.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

NetBSD

Updated:  November 02, 2000

Status

  Not Vulnerable

Vendor Statement

The problem reported does not apply to NetBSD, as no version of NetBSD uses FreeBSD's "periodic" script for scheduling periodic tasks.

Vendor Information

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

OpenBSD

Notified:  November 01, 2000 Updated:  November 13, 2000

Status

  Not Vulnerable

Vendor Statement

As far as we know [periodic is FreeBSD specific]. We have various cron jobs, but we've done extensive work to fix security issues in them.

Vendor Information

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

Addendum

CERT/CC believes that the 'periodic' script is normally used only with FreeBSD.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Caldera

Notified:  November 02, 2000 Updated:  November 13, 2000

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

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

Addendum

CERT/CC believes that the 'periodic' script is normally used only with FreeBSD.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Data General

Notified:  November 02, 2000 Updated:  November 13, 2000

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

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

Addendum

CERT/CC believes that the 'periodic' script is normally used only with FreeBSD.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Debian

Notified:  November 02, 2000 Updated:  November 13, 2000

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

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

Addendum

CERT/CC believes that the 'periodic' script is normally used only with FreeBSD.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Fujitsu

Notified:  November 02, 2000 Updated:  November 13, 2000

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

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

Addendum

CERT/CC believes that the 'periodic' script is normally used only with FreeBSD.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Hewlett Packard

Notified:  November 02, 2000 Updated:  November 13, 2000

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

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

Addendum

CERT/CC believes that the 'periodic' script is normally used only with FreeBSD.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

NCR

Notified:  November 02, 2000 Updated:  November 13, 2000

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

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

Addendum

CERT/CC believes that the 'periodic' script is normally used only with FreeBSD.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

NEC

Notified:  November 02, 2000 Updated:  November 13, 2000

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

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

Addendum

CERT/CC believes that the 'periodic' script is normally used only with FreeBSD.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

RedHat

Notified:  November 02, 2000 Updated:  November 13, 2000

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

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

Addendum

CERT/CC believes that the 'periodic' script is normally used only with FreeBSD.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

SCO

Notified:  November 02, 2000 Updated:  November 13, 2000

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

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

Addendum

CERT/CC believes that the 'periodic' script is normally used only with FreeBSD.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

SGI

Notified:  November 02, 2000 Updated:  November 13, 2000

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

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

Addendum

CERT/CC believes that the 'periodic' script is normally used only with FreeBSD.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Sequent

Notified:  November 02, 2000 Updated:  November 13, 2000

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

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

Addendum

CERT/CC believes the 'periodic' script is normally used only with FreeBSD.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Sony

Notified:  November 02, 2000 Updated:  November 13, 2000

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

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

Addendum

CERT/CC believes that the 'periodic' script is normally used only with FreeBSD.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Sun

Notified:  November 02, 2000 Updated:  November 13, 2000

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

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

Addendum

CERT/CC believes that the 'periodic' script is normally used only with FreeBSD.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Unisys

Notified:  November 02, 2000 Updated:  November 13, 2000

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

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

Addendum

CERT/CC believes that the 'periodic' script is normally used only with FreeBSD.

If you have feedback, comments, or additional information about this vulnerability, please send us email.


CVSS Metrics

Group Score Vector
Base N/A N/A
Temporal N/A N/A
Environmental N/A

References

Credit

Our thanks to David Lary of SecureWorks for reporting this vulnerability to us and providing technical detail.

This document was written by Shawn Hernan.

Other Information

CVE IDs: CVE-2000-0890
Severity Metric: 0.21
Date Public: 2000-11-13
Date First Published: 2000-11-13
Date Last Updated: 2001-03-28 04:25 UTC
Document Revision: 14

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