Email-Worm:W32/Nyxem.E

Classification

Category:

Malware

Platform:

W32

Type:

Email-worm

Aliases:

W32.Blackmal.E@mm
Kama Sutra
Email-Worm.Win32.Nyxem.e
W32/MyWife.d@MM

Summary

This variant of the Nyxem worm was found in September 2004. The worm spreads itself via emails. It deletes files of various security applications.

Removal

Technical Details

Nyxem.E is similar to Email-Worm.Win32.VB.bi.

The worm has the following text strings in its body:

mysoulmustfly
offlinehacker
evilpain
setthesun

Nyxem.E is written in Visual Basic and is compiled as p-code. The size of the main executable is about 95 kilobytes.

Installation

When the worm's file is run, it first opens WinZip as a decoy. It may also block keyboard and mouse input to force the user to press CTRL + ALT + DEL and log off.

During the installation phase the worm copies its file to several locations:

%Windows%\rundll16.exe
%System%\scanregw.exe
%System%\Update.exe
%System%\Winzip.exe

where '%Windows%' indicates the main Windows folder (usually C:\WINDOWS\) and '%System%' is the Windows System folder.

Payload

The worm has a dangerous payload. If the date is equal to 3 (3rd of February, 3rd of March, etc) and the worm's UPDATE.EXE file is run, it destroys files with those extensions on all available drives:

.doc
.xls
.mdb
.mde
.ppt
.pps
.zip
.rar
.pdf
.psd
.dmp

The files' contents are replaced with a text string "DATA Error [47 0F 94 93 F4 K5]".

The payload is activated 30 minutes after the worm's file UPDATE.EXE is loaded into memory (basically 30 minutes after logon).

When the payload is activated, the worm enumerates all logical drives and damages files on them in a loop. It should damage files on all drives that have a letter. Files on local and removable drives (including USB memory) are also damaged. This should also apply to network drives, but during testing the worm failed to do affect them.

The worm attempts to disable several security-related and file sharing programs. It deletes startup key values from the Registry if they contain any of the following:

NPROTECT
ccApp
ScriptBlocking
MCUpdateExe
VirusScan Online
MCAgentExe
VSOCheckTask
McRegWiz
CleanUp
MPFExe
MSKAGENTEXE
MSKDetectorExe
McVsRte
PCClient.exe
PCCIOMON.exe
pccguide.exe
Pop3trap.exe
PccPfw
PCCIOMON.exe
tmproxy
McAfeeVirusScanService
NAV Agent
PCCClient.exe
SSDPSRV
rtvscn95
defwatch
vptray
ScanInicio
APVXDWIN
KAVPersonal50
kaspersky
TM Outbreak Agent
AVG7_Run
AVG_CC
Avgserv9.exe
AVGW
AVG7_CC
AVG7_EMC
Vet Alert
VetTray
OfficeScanNT Monitor
avast!
DownloadAccelerator
BearShare

The following startup Registry keys are affected:

[HKLM\Software\Microsoft\Windows\CurrentVersion\Run]
[HKLM\Software\Microsoft\Windows\CurrentVersion\Run]
[HKLM\Software\Microsoft\Windows\CurrentVersion\RunServices]

The worm deletes files from the following subfolders in the Program Files folder:

\DAP\*.dll
\BearShare\*.dll
\Symantec\LiveUpdate\*.*
\Symantec\Common Files\Symantec Shared\*.*
\Norton AntiVirus\*.exe
\Alwil Software\Avast4\*.exe
\McAfee.com\VSO\*.exe
\McAfee.com\Agent\*.*
\McAfee.com\shared\*.*
\Trend Micro\PC-cillin 2002\*.exe
\Trend Micro\PC-cillin 2003\*.exe
\Trend Micro\Internet Security\*.exe
\NavNT\*.exe
\Kaspersky Lab\Kaspersky Anti-Virus Personal\*.ppl
\Kaspersky Lab\Kaspersky Anti-Virus Personal\*.exe
\Grisoft\AVG7\*.dll
\TREND MICRO\OfficeScan\*.dll
\Trend Micro\OfficeScan Client\*.exe
\LimeWire\LimeWire 4.2.6\LimeWire.jar
\Morpheus\*.dll

In addition the worm reads location of certain programs from Windows Registry and deletes certain files in these locations. The affected software is:

VirusProtect6
Norton AntiVirus
Kaspersky Anti-Virus Personal
Iface.exe
Panda Antivirus 6.0 Platinum

The worm also closes application windows that have the following strings in their captions:

SYMANTEC
SCAN
KASPERSKY
VIRUS
MCAFEE
TREND MICRO
NORTON
REMOVAL
FIX

For some reason the worm adds several license keys to the Registry. Most of them seem to belong to VB6 controls. Also the worm makes changes to the registry.

The worm can modify Active Desktop files in order to launch another copy of itself named 'WinZip_Tmp.exe' using the ActiveX control.

Infection Counter

Whenever the worm infects a computer it opens a web browser on a certain webpage. This increments an infection counter on that webpage.

We were contacted by the organization that runs the site with that counter. They informed us that the counter readings were not accurate. There were multiple hits from the same IPs to the counter.

According to the latest information we received, the number of hits from unique IPs is over 300000 which is still quite big.

Propagation (email)

The worm collects email addresses from files with following extensions:

.HTM
.DBX
.EML
.MSG
.OFT
.NWS
.VCF
.MBX
.IMH
.TXT
.MSF

The worm searches for files with these extensions in Internet Explorer cache folders. email addresses that have any of the following substrings are ignored by the worm:

SYMANTEC
MCAFEE
VIRUS
TREND
PANDA
SECUR
SPAM
NORTON
ANTI
CILLIN
CA.COM
KASPER
TRUST
AVG
GROUPS.MSN
NOMAIL.YAHOO.COM
SCRIBE
EEYE
MICROSOFT
@HOTMAIL
@HOTPOP
@YAHOOGROUPS

The worm sends itself as attachment in the infected email. The email subject can be one the following:

The Best Videoclip Ever
School girl fantasies gone bad
A Great Video
Fuckin Kama Sutra pics
Arab sex DSC-00465.jpg
give me a kiss
*Hot Movie*
Fw: Funny :)
Fwd: Photo
Fwd: image.jpg
Fw: Sexy
Re:
Fw:
Fw: Picturs
Fw: DSC-00465.jpg
Word file
eBook.pdf
the file
Part 1 of 6 Video clipe
You Must View This Videoclip!
Miss Lebanon 2006
Re: Sex Video
My photos

The message body may be one of the following:

Note: forwarded message attached.
Hot XXX Yahoo Groups
F*ckin Kama Sutra pics
ready to be F*CKED ;)
forwarded message attached.
VIDEOS! FREE! (US$ 0,00)
Please see the file.
>> forwarded message ----- forwarded message ----- i just any one see my photos. It's Free :) how are you? i send the details. OK ?

The worm usually attached itself to email messages as an executable file. It uses one the following names in attachment:

007.pif
School.pif
04.pif
photo.pif
DSC-00465.Pif
image04.pif
677.pif
New_Document_file.pif
eBook.PIF
document.pif
DSC-00465.pIf

Sometimes, the worm MIME-encodes the file. In these cases, the attachment name can be one of the following:

Video_part.mim
Attachments00.HQX
Attachments001.BHX
Attachments[001].B64
3.92315089702606E02.UUE
SeX.mim
Sex.mim
Original Message.B64
WinZip.BHX
eBook.Uu
Word_Document.hqx
Word_Document.uu

The filename inside MIME-encoding is one of the following:

New Video,zip .sCr
Attachments,zip .SCR
Atta[001],zip .SCR
Clipe,zip .sCr
WinZip,zip .scR
Adults_9,zip .sCR
Photos,zip .sCR
Attachments[001],B64 .sCr
392315089702606E-02,UUE .scR
SeX,zip .scR
WinZip.zip .sCR
ATT01.zip .sCR
Word.zip .sCR

Propagation (Network Shares)

The worm has several network spreading routines. One of them enumerates all available shares, then reads the values of the following registry keys:

[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders] "Recent" "Personal"

The above registry key values point to user's folders where personal documents and recently opened files are stored.

If a matching folder is found, the worm opens it, enumerates files there, "borrows" one randomly selected file name and adds an EXE extension to it. Then the worm copies itself to network shares using the newly created name.

If the worm does not find any files in those folders, it copies itself to network shares with the following names:

New WinZip File.exe
Zipped Files.exe
movies.exe

The other network spreading routine searches for specific network shares and tries to copy itself using one of the following filenames:

\Admin$\WINZIP_TMP.exe
\c$\WINZIP_TMP.exe
\c$\Documents and Settings\All Users\Start Menu\Programs\Startup\WinZip Quick Pick.exe

At the same time the worm deletes the following file:

\c$\Documents and Settings\All Users\Start Menu\Programs\Startup\WinZip Quick Pick.lnk

Before spreading the worm checks whether a remote computer has any of the following folders and if it does, the worm tries to delete all files from that folder:

\C$\Program Files\Norton AntiVirus
\C$\Program Files\Common Files\symantec shared
\C$\Program Files\Symantec\LiveUpdate
\C$\Program Files\McAfee.com\VSO
\C$\Program Files\McAfee.com\Agent
\C$\Program Files\McAfee.com\shared
\C$\Program Files\Trend Micro\PC-cillin 2002
\C$\Program Files\Trend Micro\PC-cillin 2003
\C$\Program Files\Trend Micro\Internet Security
\C$\Program Files\NavNT
\C$\Program Files\Panda Software\Panda Antivirus Platinum
\C$\Program Files\Kaspersky Lab\Kaspersky Anti-Virus Personal
\C$\Program Files\Kaspersky Lab\Kaspersky Anti-Virus Personal Pro
\C$\Program Files\Panda Software\Panda Antivirus 6.0
\C$\Program Files\CA\eTrust EZ Armor\eTrust EZ Antivirus

The worm also creates a scheduled task to run the worm's files on remote computer with system priviledges at the 59th minute of the current hour.

Registry Modifications

Creates these keys:

[HKLM\Software\Microsoft\Windows\CurrentVersion\Run] "ScanRegistry" = "%System%\scanregw.exe /scan" [HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\CabinetState] "FullPath" = dword:00000001
[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced] "ShowSuperHidden" = dword:00000000
[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced] "WebView" = dword:00000000

[HKLM\Software\Microsoft\Windows\CurrentVersion\Run] "ScanRegistry" = "%System%\scanregw.exe /scan" [HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\CabinetState] "FullPath" = dword:00000001
[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced] "ShowSuperHidden" = dword:00000000
[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced] "WebView" = dword:00000000

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