Vulnerability Note VU#424080

shadow-utils useradd creates temporary files insecurely

Original Release date: 08 Nov 2001 | Last revised: 08 Nov 2001

Overview

Shadow-utils is an encryption and account management package freely distributed for many Linux implementations. The useradd program in this package creates insecure temporary files with predictable names in a write-protected directory. If this directory is changed to be writable, an attacker may be able to use a symbolic link attack to overwrite arbitrary files.

Description

The useradd program calls the passwd program, which stores temporary files with predictable names in /etc/default, a protected directory. The program does not check for prior existence or ownership of these files. Useradd normally runs with setuid root privileges.

Impact

If /etc/default is changed to be world-writable, an attacker may be able to create a symbolic link with predictable name, and point it to any writable file on the system. This may cause corruption of the file.

Solution

Apply vendor patches; see the Systems Affected section below.

Change /etc/default to not be world-writable.

Systems Affected (Learn More)

VendorStatusDate NotifiedDate Updated
ImmunixAffected10 Jan 200104 Oct 2001
MandrakeSoftAffected10 Jan 200104 Oct 2001
CalderaNot Affected09 Oct 200129 Oct 2001
DebianUnknown09 Oct 200108 Nov 2001
IBMUnknown09 Oct 200108 Nov 2001
SequentUnknown09 Oct 200108 Nov 2001
If you are a vendor and your product is affected, let us know.

CVSS Metrics (Learn More)

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

References

Credit

This vulnerability was first reported by Greg Kroah-Hartman

This document was last modified by Tim Shimeall.

Other Information

  • CVE IDs: CAN-2001-0120
  • Date Public: 10 Jan 2001
  • Date First Published: 08 Nov 2001
  • Date Last Updated: 08 Nov 2001
  • Severity Metric: 0.30
  • Document Revision: 10

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