-----BEGIN PGP SIGNED MESSAGE----- __________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN Solaris 2.x lp Print Service Vulnerability May 13, 1997 16:00 GMT Number H-56 ______________________________________________________________________________ PROBLEM: A vulnerability exists in the lp print service temporary files creation. PLATFORM: Solaris 2.4, 2.5 and 2.5.1. Earlier versions of Solaris may also be vulnerable. DAMAGE: This vulnerability may allow local users to gain lp privileges, which may be leveraged to gain root access. SOLUTION: Until vendor patches are made available, apply the workaround in Section 3.1. ______________________________________________________________________________ VULNERABILITY Exploit details involving this vulnerability have been made ASSESSMENT: publicly available. ______________________________________________________________________________ [ Start AUSCERT Advisory ] =========================================================================== AA-97.15 AUSCERT Advisory Solaris 2.x lp temporary files creation vulnerability 13 May 1997 Last Revised: -- - ---------------------------------------------------------------------------- AUSCERT has received information that a vulnerability exists in the lp print service under Solaris 2.4, 2.5 and 2.5.1. Earlier versions of Solaris may also be vulnerable. This vulnerability may allow local users to gain lp privileges. This may be leveraged to gain root privileges. Exploit information involving this vulnerability has been made publicly available. AUSCERT recommends that sites take the steps outlined in section 3 as soon as possible. This advisory will be updated as more information becomes available. - ---------------------------------------------------------------------------- 1. Description AUSCERT has received information that a vulnerability exists in the Solaris 2.x lp print service. The lp print service is used to print files on local and remote printers. This problem is known to be present in the lp print service distributed with Solaris 2.4, 2.5 and 2.5.1. Earlier versions of Solaris may also be vulnerable. Due to a problem with insecure file creation, it is possible to force the lp print service to create, or overwrite arbitrary files with the privileges of the lp user. This may be leveraged to gain root privileges. Exploit information involving this vulnerability has been made publicly available. 2. Impact Local users may create arbitrary files as the lp user. This may be leveraged to gain root access. 3. Workarounds/Solution AUSCERT recommends that sites prevent the exploitation of this vulnerability in the lp print service by immediately applying the workaround given in Section 3.1. Currently there are no vendor patches available that address this vulnerability. AUSCERT recommends that official vendor patches be installed when they are made available. 3.1 Modify lp configuration To prevent the exploitation of the vulnerability described in this advisory, AUSCERT recommends applying the following steps: 1. su to root 2. Before continuing, all printing services must be stopped and the printing queue emptied. To reject any new jobs to the printing queue use the command: # /usr/sbin/reject printer_queue and wait until the printing queue is emptied. To stop the print service use the command: # /etc/init.d/lp stop Print services stopped. 3. The file /etc/init.d/lp needs to be edited to set the umask for this service to 022. Files created by lp printing service will now inherit this umask and not be created as world writable. Using your favorite editor, edit the file /etc/init.d/lp and change the line state=$1 to umask 022 state=$1 4. The original log files may have been created with insecure permission settings, therefore containing information that cannot be trusted. Its best to rename or remove these files. The files will be re-created by lp printing service with the correct permissions after the printing service is re-started. Before executing the following commands make sure that there are no jobs pending on the queue. # mv -i /var/lp/logs/lpNet /var/lp/logs/lpNet.previous # mv -i /var/lp/logs/lpsched /var/lp/logs/lpsched.previous # mv -i /var/lp/logs/requests /var/lp/logs/requests.previous 5. Change the default location of the temporary files to /var/lp/ # echo 'Options: PRINTER * = -L/var/lp/*.log' | lpfilter -f postio - # echo 'Options: PRINTER * = -L/var/lp/*.log' | lpfilter -f postior - 6. Re-start printing services: # /etc/init.d/lp start Print services started. 7. If you used the command reject on step 2, use the following command to allow printing queue to be re-enabled: # /usr/sbin/accept printer_queue [ End AUSCERT Advisory ] ______________________________________________________________________________ CIAC wishes to acknowledge the contributions of AUSCERT and Sun Microsystems for the information contained in this bulletin. ______________________________________________________________________________ CIAC, the Computer Incident Advisory Capability, is the computer security incident response team for the U.S. Department of Energy (DOE) and the emergency backup response team for the National Institutes of Health (NIH). CIAC is located at the Lawrence Livermore National Laboratory in Livermore, California. CIAC is also a founding member of FIRST, the Forum of Incident Response and Security Teams, a global organization established to foster cooperation and coordination among computer security teams worldwide. CIAC services are available to DOE, DOE contractors, and the NIH. CIAC can be contacted at: Voice: +1 510-422-8193 FAX: +1 510-423-8002 STU-III: +1 510-423-2604 E-mail: ciac@llnl.gov For emergencies and off-hour assistance, DOE, DOE contractor sites, and the NIH may contact CIAC 24-hours a day. During off hours (5PM - 8AM PST), call the CIAC voice number 510-422-8193 and leave a message, or call 800-759-7243 (800-SKY-PAGE) to send a Sky Page. CIAC has two Sky Page PIN numbers, the primary PIN number, 8550070, is for the CIAC duty person, and the secondary PIN number, 8550074 is for the CIAC Project Leader. Previous CIAC notices, anti-virus software, and other information are available from the CIAC Computer Security Archive. World Wide Web: http://ciac.llnl.gov/ Anonymous FTP: ciac.llnl.gov (128.115.19.53) Modem access: +1 (510) 423-4753 (28.8K baud) +1 (510) 423-3331 (28.8K baud) CIAC has several self-subscribing mailing lists for electronic publications: 1. CIAC-BULLETIN for Advisories, highest priority - time critical information and Bulletins, important computer security information; 2. CIAC-NOTES for Notes, a collection of computer security articles; 3. SPI-ANNOUNCE for official news about Security Profile Inspector (SPI) software updates, new features, distribution and availability; 4. SPI-NOTES, for discussion of problems and solutions regarding the use of SPI products. Our mailing lists are managed by a public domain software package called Majordomo, which ignores E-mail header subject lines. 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If you are not part of these communities, please contact your agency's response team to report incidents. Your agency's team will coordinate with CIAC. The Forum of Incident Response and Security Teams (FIRST) is a world-wide organization. A list of FIRST member organizations and their constituencies can be obtained via WWW at http://www.first.org/. This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes. LAST 10 CIAC BULLETINS ISSUED (Previous bulletins available from CIAC) H-48: Internet Information Server Vulnerability H-49: NLS Buffer Overflow Vulnerability H-22a: talkd Buffer Overrun Vulnerability H-29a: HP-UX sendmail Patches Vulnerability H-50: HP-UX SYN Flood and libXt patches H-51: Vulnerability in libXt H-52: IRIX csetup Program Vulnerability H-53: Vulnerability in webdist.cgi H-54: Vulnerability in xlock H-55: IRIX netprint Program Security Vulnerability -----BEGIN PGP SIGNATURE----- Version: 4.0 Business Edition iQCVAwUBM3owmbnzJzdsy3QZAQHScwQAjwbFLsT8aSWtIDEnp4DWXWGmBT1ZkNPJ kXOILRu9Ie9LGpEknzgg5tjUja4Jcnx7SD9W7WopCQw3ghAdD09u9zdtoE/IoZww hNjRpVPX/cp5V1ihnPw4O9r1iM2bBMC7+xbFRB4KaRXiynGWtaiKk+p7qHZoAxi9 OK6keqoQY+8= =pt6N -----END PGP SIGNATURE-----