Security Vulnerability in inetd(1M) Daemon When Debug Logging is Enabled

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Security Vulnerability in inetd(1M) Daemon When Debug Logging is Enabled

1. Impact

The inetd(1M) daemon will log debug messages to the log file /var/tmp/inetd.log if this file exists. A local unprivileged user may be able to create a link from this log file to another file on the system, allowing the user to modify that file. This could result in a Denial of Service (DoS).

2. Contributing Factors

This issue can occur in the following releases:

SPARC Platform

• Solaris 10 without patch 127718-05

x86 Platform

• Solaris 10 without patch 127719-05

Note: Solaris 8 and 9 are not impacted by this issue

To determine if inetd(1M) is logging messages to a file, the following command can be run:

$ ls /var/tmp/inetd.log

The presence of the inetd.log file indicates inetd(1M) is logging messages.

3. Symptoms

There are no predictable symptoms that would indicate the described issue has been exploited.

4. Workaround

To prevent this issue from being exploited to modify any file on the system, the root user (uid 0) can create the debug log file "/var/tmp/inetd.log". If a root owned /var/tmp/inetd.log file exists, a local unprivileged user will not be able to create a link from the inetd debug log to another file. For example:

# /usr/bin/rm /var/tmp/inetd.log
# /usr/bin/touch /var/tmp/inetd.log
# /usr/bin/ls -l /var/tmp/inetd.log
-rw-r--r-- 1 root root 0 Feb 13 14:42 /var/tmp/inetd.log

5. Resolution

This issue is addressed in the following releases:

SPARC Platform

• Solaris 10 with patch 127718-05 or later

x86 Platform

• Solaris 10 with patch 127719-05 or later

For more information on Security Sun Alerts, see Technical Instruction ID 213557.

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Modification History

28-Apr-2008: Updated Resolution section to add link for Security Technical Instruction doc

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