105 lines
5.2 KiB
Plaintext
105 lines
5.2 KiB
Plaintext
ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿
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³ VIRUS REPORT ³
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³ Swap ³
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ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ
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Synonyms: Israeli Boot, Falling Letters Boot, Fat 12
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Date of Origin: August, 1989.
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Place of Origin: Israel.
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Host Machine: PC compatibles.
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Host Files: Remains resident. Infects floppy disk boot sector.
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OnScreen Symptoms: Cascading letters on screen 10 minutes after
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activation.
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Increase in Size of Infected Files: n/a. The virus code is 740 bytes. It
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uses 2K of memory, once resident.
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Nature of Damage: Corrupts or overwrites boot sector.
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Detected by: Scanv56+, F-Prot, IBM Scan.
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Removed by: MDisk, CleanUp, F-Prot, or the DOS SYS command.
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First studied by Yuval Tal of Israel, and called "the swap virus"
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because the message "The Swapping-Virus..." sometimes appears in it and
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the words "SWAP VIRUS FAT12" appeared in a modified boot sector on his
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disk. Other virus researchers cannot see how the virus would produce
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this code, and have suggested that Mr. Tal placed the words there
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himself, to help him identify the virus. Since the other researchers
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haven't found the word "SWAP" anywhere, they have argued against the
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name "Swap", but no one has come up with a better one. "Israeli boot
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virus" will suffice only until there is a second virus from Israel that
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infects the boot sector (3-4 minutes from now, at the rate we're going!).
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At any rate, this virus may write the following string into bytes
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B7-E4 of track 39, sector 7 (if sectors 6 and 7 are empty):
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The Swapping-Virus. (C) June, 1989 by the CIA
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When this virus replicates, however, the message transfers as binary
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zeros. Someone may have placed the text message into the virus thinking
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that it would replicate along with the virus.
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The Swap virus is somewhat different from other PC boot sector
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viruses. Normally a BSV replaces the boot sector with virus code, and
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stores the original boot sector somewhere. In some cases (Ping-Pong,
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Typo, Brain) the boot sector is stored in unused space, which is then
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marked as bad in the FAT. In other cases (Yale, Den Zuk, StonedDen Zuk
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virus), the virus stores the boot sector in a sector that is not likely
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to be used. One virus (Pentagon) even stores the boot sector in a hidden
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file.
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When the computer is booted from a disk infected with the a normal
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boot sector infecting virus, the code on the boot sector will read the
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rest of the virus into memory. The virus will then install itself, read
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the original boot sector and transfer control to it.
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Swap is different. It does not store the original boot sector at
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all. Instead it assumes that bytes 196-1B4 (hex) on the boot sector
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contain error messages that can be safely overwritten. This is true for
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most (but not all) boot sectors. It also assumes that the boot sector
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starts with a JMP instruction. Swap then replaces these bytes with code
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to read the rest of the virus (which is stored at track 39, sectors 6 and
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7) into memory. The virus will then execute the original boot code. The
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fact that this virus does not store the original boot sector makes it
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hard (and in some cases impossible) to repair an infected
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diskette.<Note: Some of this information was provided by Fridrik
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Skulason of the University of Iceland.>
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The Swap virus activates after being memory resident for 10 minutes.
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A cascading effect of letters and characters on the system monitor is
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then seen, similar to the cascading effect of the Cascade and Traceback
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viruses.
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ÉÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ»
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º This document was adapted from the book "Computer Viruses", º
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º which is copyright and distributed by the National Computer º
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º Security Association. It contains information compiled from º
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º many sources. To the best of our knowledge, all information º
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º presented here is accurate. º
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º º
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º Please send any updates or corrections to the NCSA, Suite 309, º
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º 4401-A Connecticut Ave NW, Washington, DC 20008. Or call our BBS º
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º and upload the information: (202) 364-1304. Or call us voice at º
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º (202) 364-8252. This version was produced May 22, 1990. º
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º º
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º The NCSA is a non-profit organization dedicated to improving º
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º computer security. Membership in the association is just $45 per º
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º year. Copies of the book "Computer Viruses", which provides º
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º detailed information on over 145 viruses, can be obtained from º
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º the NCSA. Member price: $44; non-member price: $55. º
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º º
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º The document is copyright (c) 1990 NCSA. º
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º º
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º This document may be distributed in any format, providing º
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º this message is not removed or altered. º
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ÈÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍͼ
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