Net-Worm:W32/Nimda.E is not compressed. It uses the same techniques as Nimda.A, except it spreads itself with SAMPLE.EXE file name.
Other minor differences are as follows:
- The worm uses COOL.DLL name to upload itself to webservers
- The worm uses HTTPODBC.DLL name to start from on servers
- The worm uses CSRSS.EXE name to copy itself to servers
This version of Nimda has few serious bugs that allow it to infect files several times and to jam NT systems considerably.
On October 30th, F-Secure received reports of live infections in Germany and Sweden. On October 31st, we received further reports from USA, China, France, Norway, Finland and Spain.
Apparently the author of Nimda was offended because his virus wasn't named "Concept Virus" like he wanted. The virus code contains a copyright text string which is never displayed, saying "Concept Virus(CV) V.6, Copyright(C)2001, (This's CV, No Nimda.)"
The actual lifecycle of Nimda can be split to four parts:
- Infecting files
- Mass mailing
- Web worm
- LAN propagation