Details Angela This is a multipartite virus infecting hard drive MBR sector, floppy drives boot sector, DOS EXE file as well as spreading via IRC channels by infecting the mIRC client, as well as mailing itself by using MS Outlook. The virus may appear on a computer on an infected floppy disk, as an infected DOS EXE file, or as an infected attachment in an e-mail message. The virus has no payloads and does not manifest itself in any way except one – it deletes the file: C:\WINDOWS\SYSTEM\IOSUBSYS\HSFLOP.PDR The virus needs to delete this file to force Windows to operate the floppy-disk sectors by using an old-style INT 13h way (this is necessary for thevirus to run its disk infection and stealth routines, see below). Booting from an infected disk Upon loading from an infected disk, the virus hooks INT 13h (disk access) and INT 1Ch (timer). By using a timer hook, the virus waits until a system is booting up, then hooks INT 21h (DOS functions) and infects DOS EXE files that are executed. By hooking INT 13h, the virus gets access to floppy disks and infects their boot sectors. The virus also realizes {stealth:Stealth} a function upon accessing infected disk sectors. Infected DOS EXE file run Upon being run from an infected DOS EXE file, the virus infects the hard drive’s MBR sector, creates and registers its DOS EXE dropper, creates a VBS script program to spread with e-mail, and creates an mIRC script to be sent to IRC channels. The virus dropper has the ANGELA.EXE name and is created in the C:\WINDOWS\SYSTEM directory (If Windows is installed in another directory, the virus cannot spread to IRC and in e-mail). This file is registered to be run upon each rebooting in the C:\AUTOEXEC.BAT file. The virus writes a command to there to run this file upon each reboot, and adds comments to that file: @ECHO OFF c:\windows\system\angela.exe REM – DO NOT REMOVE! The virus dropper does the same as the virus does in infected DOS EXE file does; i.e., if any of the virus components (VBS or mIRC script) are deleted, the virus will re-create it upon the next reboot. Mailing The virus creates the ANGELA.VBS file in the Windows start-up directory, and as a result, this script is activated upon each Windows boot-up. The program in the script access MS Outlook obtains address book records, and sends a virus copy (the ANGELA.EXE dropper) to the first 20 addresses that are found there. The message has: Subject: Finally found it! Body: Here are the files you asked me forall Attachment name: angela.exe The script then deletes its VBS file, and there are no more infected messages sent during the same Windows seance, but upon he tnext computer reboot, the ANGELA.EXE dropper will be activated from AUTOEXEC.BAT, and it will re-create the VBS mailing routine. Infecting IRC channels The virus creates the SCRIPT.INI file in the C:\MIRC directory. This script sends an ANGELA.EXE dropper to all users that join the infected IRC channel.

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