NO RESTRICTIONS _____________________________________________________ The Computer Incident Advisory Capability ___ __ __ _ ___ / | / \ / \___ __|__ /___\ \___ _____________________________________________________ INFORMATION BULLETIN New Virus on Macintosh Computers: MBDF A February 25, 1992, 1130 PST Number C-17 ________________________________________________________________________ NAME: MBDF A virus PLATFORM: Macintosh computers-except MacPlus and SE (see below) DAMAGE: May cause program crashes SYMPTOMS: Claris applications indicate they have been altered; some shareware may not work, unexplained system crashes DETECTION & ERADICATION: Disinfectant 2.6,Gatekeeper 1.2.4, Virex 3.6, VirusDetective 5.0.2, Rival 1.1.10, SAM 3.0 ________________________________________________________________________ Critical Facts about MBDF A A new Macintosh virus, MBDF A, (named for the resource it exploits) has been discovered. This virus does not appear to maliciously cause damage, but simply copies itself from one application to another. MBDF A was discovered at two archive sites in newly posted game applications, and has a high potential to be very widespread. Infection Mechanism This virus is an "implied loader" virus, and it works in a similar manner to other implied loader viruses such as CDEF and MDEF. Once the virus is active, clean appliacation programs will become infected as soon as they are executed. MBDF A infects only applications, and does not affect data files. This virus replicates under both System 6 and System 7. While MBDF A may be present on ALL types of Macintosh systems, it will not spread if the infected system is a MacPlus or a Mac SE (although it does spread on an SE/30). Potential Damage The MBDF A virus has no malicious damaging characteristics, however, it may cause programs to inexplicably crash when an item is selected from the menu bar. Some programs, such as the shareware "BeHierarchic" program, have been reported to not operate correctly when infected. Applications written with self-checking code, such as those written by the Claris corporation, will inform the user that they have been altered. When MBDF A infects the system file, it must re-write the entire system file back to disk; this process may take two or three minutes. If the user assumes the system has hung, and reboots the Macintosh while this is occuring, the entire system file will be corrupted and an entire reload of system software must then be performed. This virus can be safely eradicated from most infected programs, although CIAC recommends that you restore all infected files from an uninfected backup. Detection and Eradication Because MBDF A has been recently discovered, only anti-viral packages updated since February 20, 1992 will locate and eradicate this virus. All the major Macintosh anti-viral product vendors are aware of this virus and have scheduled updates for their products. These updates have all been available since February 24, 1992. The updated versions of some products are Disinfectant 2.6, Gatekeeper 1.2.4, Virex 3.6, SAM 3.0, VirusDetective 5.0.2, and Rival 1.1.10. Some Macintosh applications (such as the Claris software mentioned above) may contain self-verification procedures to ensure the program is valid before each execution; these programs will note unexpected alterations to their code and will inform the user. MBDF A has been positively identified as present in two shareware games distributed by reliable archive sites: "Obnoxious Tetris" and "Ten Tile Puzzle". The program "Tetricycle" (sometimes named "Tetris-rotating") is a Trojan Horse program which installs the virus. If you have downloaded these or any other software since February 14, 1992 (the day these programs were loaded to the archive sites), CIAC recommends that you acquire an updated version of an anti-viral product and scan your system for the existence of MBDF A. For additional information or assistance, please contact CIAC: Karyn Pichnarczyk (510) 422-1779 or (FTS) 532-1779 karyn@cheetah.llnl.gov Call CIAC at (510)422-8193/(FTS)532-8193. Send e-mail to ciac@llnl.gov PLEASE NOTE: Many users outside of the DOE and ESnet computing communities receive CIAC bulletins. If you are not part of these communities, please contact your agency's response team to report incidents. Some of the other teams include the NASA NSI response team, DARPA's CERT/CC, NAVCIRT, and the Air Force response team. Your agency's team will coordinate with CIAC. CIAC would like to thank Gene Spafford and John Norstad, who provided some of the information used in this bulletin. 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