W97M/ColdApe infects documents when they are closed. The virus uses a new method of replicating: instead of using traditional methods of copying it's macros around, it uses a new technique called "AddFromString". This made the virus undetectable by several heuristic scanners.
If the virus is run under Windows 98 or Windows 2000 (NT 5) or under any Windows version running WSH (Windows Scripting Host), the virus can drop these Windows script files:
A4.VBS to the root directory
Happy.VBS to the root directory
AVM.VBS to the Windows directory
A4.VBS is not a virus. If this script is executed, it will send an email message using Outlook (if present). The message is directed to a well-known person in the anti-virus industry.
Happy.VBS and AVM.VBS contain the script virus. This appending script virus will infect all .VBS files in these directories:
The script virus is independent of the Word Macro virus and will continue to spread even if the macro virus is disinfected.
Variant:ColdApe.B (Love Monkey)
This variant is polymorphic. This is done by prepending the current user's name, the system date and time to the end of the virus macro.
Otherwise this version is very similar to the original one.