_____________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ _____________________________________________________ INFORMATION BULLETIN IBM AIX bsh Queue Vulnerability June 3, 1994 1500 PDT Number E-29a ______________________________________________________________________________ PROBLEM: Vulnerability in bsh batch queue allows unauthorized access. PLATFORMS: IBM AIX 3.2 and earlier. DAMAGE: Remote users may gain access to a privileged account. SOLUTION: Disable the bsh queue; obtain and install fix from IBM. ______________________________________________________________________________ VULNERABILITY This vulnerability is being discussed on public mailing lists ASSESSMENT: and can be exploited remotely. CIAC recommends that sites disable the bsh queue immediately. ______________________________________________________________________________ Critical Information about the IBM AIX bsh Queue Vulnerability CIAC has learned of a vulnerability in the bsh batch queue of IBM AIX systems running AIX version 3.2 and earlier. If network printing is enabled, the bsh queue will permit users on remote systems to execute commands at an elevated privilege. CIAC recommends that the bsh queue be disabled immediately as described below. Administrators should then obtain and install the appropriate fixes from IBM. Few applications make use of the bsh queue, and IBM has agreed to disable the queue by default in future AIX releases. CIAC recommends that the bsh queue be left disabled unless its functionality is explicitly required. Disabling bsh ------------- To disable the bsh queue, perform one of the following procedures: A. As root, from the command line, enter: chqueue -qbsh -a"up = FALSE" B. From SMIT enter: - Spooler - Manage Local Printer Subsystem - Local Printer Queues - Change/Show Characteristics of a Queue select bsh - Activate the Queue select no Emergency Fix ------------- IBM has made available an emergency fix for this vulnerability via anonymous FTP from software.watson.ibm.com in the directory /pub/aix. The fix is contained in the compressed tar file bshfixN.tar.Z, where N is the current version of the fix. Installation instructions are provided in a README file in the tar package. Please note: Due to the volatile nature of emergency fixes, IBM may temporarily remove them from the FTP server while revisions are made. If you are unable to retrieve the fix from the FTP server, please try again at a later time. Official Fix ------------ The official fix for this problem will be available soon from IBM and can be ordered as APAR IX44381. To order an APAR from IBM in the U.S. call 1-800-237-5511 and ask for shipment as soon as it becomes available. To obtain APARS outside the U.S., contact a local IBM representative. ______________________________________________________________________________ CIAC thanks IBM and the CERT Coordination Center for the information provided in this advisory. ______________________________________________________________________________ For additional information or assistance, please contact CIAC: Voice: 510-422-8193 FAX: 510-423-8002 STU-III: 510-423-2604 E-mail: ciac@llnl.gov Previous CIAC Bulletins and other information are available via anonymous FTP from ciac.llnl.gov (IP address 128.115.19.53). 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. 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