Insecure Temporary File Creation In MySQL

1. Gentoo Linux Security Advisory

Advisory Reference	GLSA 200405-20 / MySQL
Release Date	May 25, 2004
Latest Revision	May 25, 2004: 01
Impact	normal
Exploitable	local

Package	Vulnerable versions	Unaffected versions	Architecture(s)
dev-db/mysql	< 4.0.18-r2	>= 4.0.18-r2	All supported architectures

Related bugreports: #46242

Synopsis

Two MySQL utilities create temporary files with hardcoded paths, allowing an attacker to use a symlink to trick MySQL into overwriting important data.

2. Impact Information

Background

MySQL is a popular open-source multi-threaded, multi-user SQL database server.

Description

The MySQL bug reporting utility (mysqlbug) creates a temporary file to log bug reports to. A malicious local user with write access to the /tmp directory could create a symbolic link of the name mysqlbug-N pointing to a protected file, such as /etc/passwd, such that when mysqlbug creates the Nth log file, it would end up overwriting the target file. A similar vulnerability exists with the mysql_multi utility, which creates a temporary file called mysql_multi.log.

Impact

Since mysql_multi runs as root, a local attacker could use this to destroy any other users' data or corrupt and destroy system files.

3. Resolution Information

Workaround

One could modify both scripts to log to a directory that users do not have write permission to, such as /var/log/mysql/.

Resolution

All users should upgrade to the latest stable version of MySQL.

Code Listing 3.1: Resolution

# emerge sync
# emerge -pv ">=dev-db/mysql-4.0.18-r2"
# emerge ">=dev-db/mysql-4.0.18-r2"

4. References

Page updated May 25, 2004

Summary: This is a Gentoo Linux Security Advisory

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