MIT krb5: Insecure temporary file use in send-pr.sh

1. Gentoo Linux Security Advisory

Advisory Reference	GLSA 200410-24 / mit-krb5
Release Date	October 25, 2004
Latest Revision	January 30, 2005: 02
Impact	normal
Exploitable	local

Package	Vulnerable versions	Unaffected versions	Architecture(s)
app-crypt/mit-krb5	<= 1.3.5	>= 1.3.5-r1, revision >= 1.3.4-r1	All supported architectures

Related bugreports: #66359

Synopsis

The send-pr.sh script, included in the mit-krb5 package, is vulnerable to symlink attacks, potentially allowing a local user to overwrite arbitrary files with the rights of the user running the utility.

2. Impact Information

Background

MIT krb5 is the free implementation of the Kerberos network authentication protocol written by the Massachusetts Institute of Technology.

Description

The send-pr.sh script creates temporary files in world-writeable directories with predictable names.

Impact

A local attacker could create symbolic links in the temporary files directory, pointing to a valid file somewhere on the filesystem. When send-pr.sh is called, this would result in the file being overwritten with the rights of the user running the utility, which could be the root user.

3. Resolution Information

Workaround

There is no known workaround at this time.

Resolution

All MIT krb5 users should upgrade to the latest version:

Code Listing 3.1: Resolution

# emerge sync

# emerge -pv ">=app-crypt/mit-krb5-1.3.4-r1"
# emerge ">=app-crypt/mit-krb5-1.3.4-r1"

4. References

CAN-2004-0971

Page updated October 25, 2004

Summary: This is a Gentoo Linux Security Advisory

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