| Alias: | |
| Strain: | - |
| detected when: | |
| where: | |
| Classification: | COM and EXE infector, resident |
| Length: | 224 paragraph(s) |
Preconditions | |
| Operating System(s): | MS-DOS |
| Version/Release: | All models |
| Computer model(s): | PC's |
| Caroname: | Drop |
Attributes | |
| Easy identification: | |
Type of Infection: | The virus appends itself to the files Selfrec in memory: Int21;AX=0FF01h --> AX=1FFh Selfrec on disk: File[EOF-2] == 0FF01h |
| Infection Technique: | |
| Infection Trigger: | (get/set_attribute || Open || Loadexec) &&(2k <= COM_filesize < 61k) |
| Storage Media affected: | |
| Interrupts hooked: | 21/43, 21/3D, 21/4B00, 21/FF01, 24, 1C |
| Stealth: | |
| Tunneling/Selfprot: | |
| Oligo/Polymorphism: | - |
| Encoding Method: | |
| Damage: | Transient: All characters on the screen drop down to form columns atthe bottom of the screen. Permanent: - |
| Damage Trigger: | Transient: Day_of_Month == 6 && (0 <= Video_mode <= 3) Permanent: - |
| Particularities: | The virus resides above the last MCB because of a bug in the timer handler, the machine hangs afterthe first time the video drop is performed. The timer routine checks the current video mode every 2 minutesand performs the screen drop if the video mode is suitable. |
| Similarities: | |
Agents | |
| Countermeasures: | |
| Standard means: | |
Acknowledgements | |
| Location: | Virus Test Center, University Hamburg, FRG |
| Classification by: | Adam David, Frisk Software International |
| Documentation by: | Adam David, Frisk Software International |
| Date: | 28.7.93 |
| Information Source: | Caroentry (autom.converter by S.Freitag) |
(c) 1996 Virus-Test-Center, University of Hamburg