NetSky.X worm was discovered on April 20th, 2004.This variant is extremely close to the latest NetSky variants. It shares up to approximately 86% of the code and features in common with NetSky.U.
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Netsky.X sends messages in several different languages: English, Swedish, Finnish, Polish, Norwegian, Portuguese, Italian, French, German and possibly the language of some small island called Turks and Caicos, located in the Atlantic ocean. In many cases the messages are composed incorrectly suggesting that the worm's author did not ask native speakers for translation or used an on-line translation service like Babel Fish.
It looks like the Netsky's author mistyped the domain suffix for Turkey - he put '.tc' instead of '.tr'. We came to that conclusion after verifying that the text that is sent to addresses in .tc domain is in Turkish (word by word translation from dictionary).
The worm's file is a PE executable 26112 bytes long packed with PE-Patch and TeLock file compressors.
Some of the worm's text strings are scrambled using the same algorithm as all the other variants.
Upon execution NetSky.X copies itself as FirewalSrv.exe file to Windows folder and adds a startup key for this file into System Registry:
[HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run] "FirewallSvr" = "%WinDir%\FirewallSvr.exe"
where %WinDir% represents Windows folder name.
Before spreading in email the worm collects email addresses. It scans all files on all drives from C: to Z: except CD-ROM drives. If any file with the following extensions is found, the worm opens it and searches for email addresses there:
.eml .txt .php .cfg .mbx .mdx .asp .wab .doc .vbs .rtf .uin .shtm .cgi .dhtm .adb .tbb .dbx .pl .htm .html .sht .oft .msg .ods .stm .xls .jsp .wsh .xml .mht .mmf .nch .ppt
The worm composes two different types of messages. According to whether the destination address is one of the following domains:
.tc .se .fi .pl .no .pt .it .fr .de .xx
It will compose messages in the corresponding language, choosing from the following parts.
Subjects chosen from:
Re: belge Re: dokumenten Re: dokumentoida Re: udokumentowac Re: dokumentet Re: original Re: documento Re: dokument Re: document
Bodies chosen from:
mutlu etmek okumak Belgiëli tanimlik belge. Behaga lasa dokumenten. Haluta kuulua dokumentoida. Podobac sie przeczytac ten udokumentowac. Behage lese dokumentet. Leia por favor o original. Legga prego il documento. Veuillez lire le document. Bitte lesen Sie das Dokument. Please read the document.
belge.pif dokumenten.pif dokumentoida.pif udokumentowac.pif dokumentet.pif original.pif documento.pif dokument.pif document.pif
Netsky.X has a payload. It performs a DoS (Denial of Service) attack on the following websites from 28th to 30rd of April 2004:
www.nibis.de www.medinfo.ufl.edu www.educa.ch