1. Topic:
New lpr packages are available to fix two security problems in lpd.

2. Problem description:
Two security vulnerabilities exist in the lpd (line printer daemon) shipped with the lpr package.

First, authentication was not thorough enough. If a remote user was able to control their own DNS so that their IP address resolved to the hostname of the print server, access would be granted, when it should not be.

Secondly, it was possible in the control file of a print job to specify arguments to sendmail. By careful manipulation of control and data files, this could cause sendmail to be executed with a user-specified configuration file. This could lead very easily to a root compromise.

It is recommended that all users of Red Hat Linux using the lpr package (which is required to print) upgrade to the fixed packages.

Thanks go to DilDog (dildog@l0pht.com) for noting the vulnerability.

If you are experiencing problems with local printing in Red Hat Linux 6.1, make sure that you have:

alias parport_lowlevel parport_pc

in your /etc/conf.modules file.

3. Bug IDs fixed: (see bugzilla for more information)

4. Relevant releases/architectures:
Red Hat Linux 6.1, all architectures

5. Obsoleted by:
None

6. Conflicts with:
None

7. RPMs required:

Intel:

lpr-0.48-1.i386.rpm

Alpha:

lpr-0.48-1.alpha.rpm

SPARC:

lpr-0.48-1.sparc.rpm

Source:

lpr-0.48-1.src.rpm

8. Solution:
For each RPM for your particular architecture, run:

rpm -Uvh filename

where filename is the name of the RPM.

Then, restart lpd:
/etc/rc.d/init.d/lpd restart

9. Verification:

 MD5 sum                           Package Name

 -------------------------------------------------------------------------
78f2220331189e723eab944b53d0710e  i386/lpr-0.48-1.i386.rpm
3fcb89eb1a76741a505d3eeeddfa3674  alpha/lpr-0.48-1.alpha.rpm
441cfee04428ca215d98d9ce3d20bc4d  sparc/lpr-0.48-1.sparc.rpm
55c6a740b03569919ec08992257cad96  SRPMS/lpr-0.48-1.src.rpm

 

You can verify each package with the following command: rpm --checksig filename

If you only wish to verify that each package has not been corrupted or tampered with, examine only the md5sum with the following command: rpm --checksig --nogpg filename

Note that you need RPM >= 3.0 to check GnuPG keys.

10. References:
Thanks to dildog@l0pht.com for finding this bug.