Two days after the initial infection the virus begins to spread to other applications. Only ones that are actually run are candidates for infection.
After four days it begins to watch for the VULT and ERIC applications. The virus identifies them by checking to see if the application contains any resources of type VULT or ERIC. Applications with creators VULT and ERIC normally contain these resources, but other applications normally don't.
Whenever one of these applications is run it bombs after 25 minutes of use. If you don't have a debugger installed you'll get a system bomb with ID=12. If you have MacsBug installed you'll get a user break.
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After seven days, whenever VULT is run the virus waits for 15 minutes, then causes any attempt to write a disk file to bomb. If you don't do any writes for another 10 minutes the application will bomb anyway, as described in the previous paragraph.
There's also more code to force a bomb after 45 minutes, but this code shouldn’t be reached, given the forced bomb after 25 minutes.