These are not dangerous memory resident companion viruses. "TerraX.2874" is a polymorphic virus based on the SDFE 1.0 polymorphic engine.
The viruses hook INT 21h and then create companion COM files while executing .EXE files. While executing .COM files the viruses rename them to .EXE extension, and then infect as .EXE files. The viruses check the file name and do not infect the files with the string at the name beginning:
COMMAND IBM ET PC TB CKVI KLVI DEVI BTOOL RTOOL TDISK SCAN CLEAN HUNT F- TR
G Z
On 18th of any month the viruses display:
+-------------------------------+_
¦ " Terra'X " ¦_
¦-------------------------------¦_
¦ Written By Zhuge Jin at TPVO. ¦_
+-------------------------------+_
_________________________________
