Selected viruses, spyware, and other threats: sorted alphabetically
Tiso |
Tiso.846
Tiso.846 is a resident encrypted multi-partite COM infector. This virus spreads only in files. When an infected file executed it attacks MBR. It modifies only 53 bytes in MBR, and moves the rest of its body to the second and the third sector of hard disk. In the third sector also a part of the original MBR is stored. The virus does not install itself to the memory from a file; the installation takes place only after the next loading of system. Then the virus overtakes the control over the interrupts INT 21h and INT8. At every 64th loading of system the virus writes, depending on the timer, the following text on the screen:
Nech zije Jozef Tiso, prvy slovensky prezident !
(Meaning: Long live Jozef Tiso, the first Slovak President!)
Tiso.940
The variant Tiso.940 occupies 2 Kb in memory. It has a simple stealth technique implemented. Depending on the timer the following text is written to the screen:
Nech zije Jozef Tiso, prvy slovensky prezident !
(Meaning: Long live Jozef Tiso, the first Slovak President!)
Tiso.1279
This variant is 1279 bytes long. It infects hard disk’s MBR, COM programs and, unlike the older variants, also EXE files. The virus is memory resident on the top of RAM and it reserves 2 Kb for its own use there. The way of its presentation is not changed considerably and after some time it writes the following text on the first line of the screen:
Nech zije Jozef Tiso, prvy slovensky prezident !
(Meaning: Long live Jozef Tiso, the first Slovak President!)
While the older variant displays the text upon a blue background this one does so on a red one. The virus is written in a rather clever way and critical errors are dealt with. Encrypting of the new version is improved, too. Value with which the XOR is cyclically implemented is taken from the previous byte and is not constant as it used to be. The virus also uses a simple stealth technology.
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