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  1. 07001020209800
  2. 1VIRUSES(1)Atari STVIRUSES(1)
  3. 218/5/89Page #18/5/89
  4. F0000000
  5. 9[................................................]011
  6. ü
  7.  
  8.  
  9.  
  10.  
  11.  
  12.  
  13.  
  14.  
  15.  
  16.  
  17.  
  18. ëVIRUSES(ST)
  19. Ç
  20. AcompaniondocumentfortheHOSPITAL
  21. virusdetection/preventionsuite
  22.  
  23. NeilForysth
  24. DepartmentofComputerScience
  25. Heriot-WattUniveristy
  26. HuntersClose
  27. 79Grassmarket
  28. Edinburgh
  29.  
  30. neil@uk.ac.hw.cs
  31.  
  32. ëTHEHOSPITALPROGRAMS
  33. Ç
  34. ItwouldbealietosaythatifyouusetheHOSPITALprograms
  35. youwillêneverÇsufferfromavirusattack.Thepeople(?)who
  36. writeviruseswilleventuallygettheseprogramsandtryto
  37. inventnewwaysofinfectionandavoidingdetection.However,
  38. usingsomecombinationoftheprogramsisdefinatelyagood
  39. precaution.Theycertainlydoagreatjobagainstallthe
  40. virusesI'veseentodateandshouldanysmartervirusescome
  41. alongIwillmodifymyprogramsaccordingly.
  42.  
  43. Treatallformatteddisksthatyouaregivenorbuywith
  44. suspicion.Thisincludescommerciallyavailiablepackages.I
  45. haveseenavirusinfecteddiskthatcamestraightoutofits
  46. clingwrappedbox.Thesoftwarehousewasnotbeing
  47. irresponsible,theywerethevictimofavirusattack.
  48.  
  49. ëOTHERHELPFULUTILITIES
  50. Ç
  51. êAFMTbyNeilForsyth
  52.  
  53. ÇInadditiontothebootsector,somediskvirusesusethe
  54. extraFATsectorsonadisk.Thereareusuallysixoftheseon
  55. singlesideddiskandfouronadouble.Theyareneverusedon
  56. thecurrentdoubledensitydisksystems.
  57.  
  58. TheAFMTdiskformatterreducesthesizeoftheFATtoa
  59. minimumleavingnofreeFATsectorsforavirustohideinand
  60. givingyoumorediskspace.
  61.  
  62. êDT(DiskToolbox)byNeilForsyth
  63.  
  64. ÇThisutilityallowsyoutoreversablychangetheexecutability
  65. ofabootsector.Ifthebootsectordoesnotcontainavirus
  66. andperhapsneedstoberunforaprogramtoworkthenitcan
  67. easilybechangedback.TheRAMloadableversionofTOSfrom
  68. Atariusesanexecutablebootsectortoloadasdoalotof
  69. commercialgames.
  70.  
  71. êVKILLERbyGeorgeWoodside
  72. Ç
  73. Thisisanexcellentprogramforthebulkcheckingofdisks
  74. forpossibleviralinfection.Ithasmanyfeaturesfor
  75. analysisanddestructionofviruses.Itcanalsotellyoua
  76. fewthingsaboutanyknownvirusesitfinds.
  77.  
  78. êFLUbyGeorgeWoodside
  79. Ç
  80. Thisprogramdemonstratesthesymptomsofmanyofthejoke
  81. typevirusesthatGeorgehascomeacross.
  82.  
  83. ëLINKVIRUSESÇ
  84.  
  85. Therearesomevirusesthatinfectprogramsinsteadofdisk
  86. sectors.Ihaveneverseenoneofthese'linkviruses'but
  87. haveaprettygoodideahowtheymightworkandhopetocreate
  88. programstosafeguardagainstthemsoon.
  89.  
  90. ëHARDDISKVIRUSESÇ
  91.  
  92. CurrentlytheredoesnotêseemÇtobeanyvirusesthatattack
  93. harddisksbutI'msurethattheywillappear.Theonlyadvice
  94. Icanofferhereistobackupyourharddiskdataregularly.
  95. IdomeanêdataÇhereandnotprograms.Youcanalwaysre-
  96. installanapplicationprogramandthecopyontheharddisk
  97. thatislostmayhavebeeninfected.
  98.  
  99. ëMYTHS
  100. Ç
  101. Therehavebeensomereports,allofthemunconfirmed,of
  102. programsthatareabletowritetodiskswiththewrite
  103. protectnotchon.Ibeleivethistobeabsolutenonsenseand
  104. probablycausedbydelayeddiskwritesfromcacheprogramsor
  105. floppyserialnumbersbeingthesame.Whenwritingmydisk
  106. formatter(AFMT),Ihadtobypasstheoperatingsystemand
  107. accessthehardwaredirectlyandnevermanagedtowritetoa
  108. writeprotecteddisk.
  109.  
  110. (FromtheWesternDigital1772DiskControllerDataSheet)
  111. 9     [........................................]011
  112.  
  113. "Writeprotect:Thisinputissampledwhenevera
  114. WriteCommandisreceived.Alogiclowonthisline
  115. willpreventanyWriteCommandfromexecuting
  116. (internalpull-up)."
  117. 9[................................................]011
  118.  
  119. Theonlywaythiscouldbecircumventedwouldbetomodifythe
  120. diskdriveoritsconnectiontothecomputer.HoweverIam
  121. openmindedenoughtobeleivethisphenomenonifandwhenI
  122. everseeitandyoucanbeprettysureI'lltellyouifIdo!
  123.  
  124.