W32/Grew.A!worm

Alias/esCME-24, Email-Worm.Win32.Nyxem.e [KAV], Kama Sutra worm [Press], W32/Grew.A!wm, W32/Kapser.A!mm, W32/Kapser.A@mm [F-Prot], W32/Nyxem-D [Sophos], WORM_GREW.A [Trend]
Release DateJan 16, 2006
Detection Availability
Active DatabaseExtended Database
FortiGatelowhigh
FortiClient
FortiMailN/A
Current Antivirus Definition Database Version: 12.323
CVECME-24
Description

Visible Symptoms

  • Possible firewall alert that these files are attempting to connect with the Internet using UDP -

    scanregw.exe
    Update.exe
    Winzip.exe

  • Compromised systems are slow to respond due to heavy outbound traffic on TCP port 445 with other machines

  • Creation of these files on the infected system [note, the System32 folder may be in a different path depending on the version of Windows and user preferences] - the files will be hidden with read-only and system attributes -

    C:\WINNT\Rundll16.exe
    C:\WINNT\system32\scanregw.exe
    C:\WINNT\system32\Update.exe
    C:\WINNT\system32\Winzip.exe

  • Virus has a file icon identical to Winzip32 application executable, and a file size of 95,690 bytes

  • Opening a viral attachment to email will display an empty ZIP similar to this one -

    Empty Winzip file displayed by W32/Grew virus

  • Data and archive files are reduced to 32 bytes from their original size

Detailed Analysis

This virus is packed with a file size of 95,690 bytes. It contains code to spread to other systems using these methods -

The virus also has the following characteristics -

Loading at Windows startup
If the threat is run manually, it will copy itself to the local system in several places -

C:\WinZip_Tmp.exe
C:\WINNT\Rundll16.exe
C:\WINNT\system32\scanregw.exe
C:\WINNT\system32\Update.exe
C:\WINNT\system32\Winzip.exe

The virus also extracts an ActiveX control to help with Internet connectivity -

C:\WINNT\system32\MSWINSCK.OCX (55,808 bytes)

The virus will register itself to load at Windows startup -

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
"ScanRegistry" = scanregw.exe /scan

SMTP mass-mailing routine
The virus uses built-in SMTP mailing routines in order for the virus to send itself to other email addresses. The virus will first harvest addresses from certain file types to create a list of potential targets, avoiding addresses containing certain texts.

The virus will try to collect usable email addresses from files having these extensions -

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

The captured addresses are used as targets for the mailing routine. As with other viruses using this technique, the virus will avoid selecting email addresses containing certain strings, such as these -

KASPER
TRUST
BLOCKSENDER
SCRIBE
YAHOOGROUPS
TREND
PANDA
SECUR
SPAM
ANTI
CILLIN
CA.COM
AVG
GROUPS.MSN
NOMAIL.YAHOO.COM
EEYE
MICROSOFT
HOTMAIL
MSN
MYWAY
@HOTMAIL
@HOTPOP

These are some of the possible file names used for the infectious attachment -

Clipe,zip .sCr
WinZip,zip .scR
04.pif
Adults_9,zip .sCR
Sweet_09
Photos,zip .sCR
Photos
007.pif
School.pif
photo.pif
Arab sex DSC-00465.jpg
DSC-00465.Pif
image04.pif
677.pif
Attachments[001],B64 .sCr
Attachments[001].B64
392315089702606E-02,UUE .scR
3.92315089702606E02.UUE
SeX,zip .scR
SeX.mim
Sex.mim
ATT01.zip .sCR
Original Message.B64
WinZip.BHX
eBook.Uu
Word.zip .sCR
Word_Document.hqx
Word XP.zip .sCR
Word_Document.uu
DSC-00465.pIf
New_Document_file.pif
eBook.pdf
eBook.PIF
document.pif
New Video,zip .sCr
Video_part.mim
Attachments,zip .SCR
Attachments00.HQX
Atta[001],zip .SCR
Attachments001.BHX
WinZip.zip .sCR

The email attachment may have one of these secondary extensions -

.PIF
.EXE
.MIM
.HQX
.BHx
.UUE
.SCR

Additional properties of the email; the attachment may have one of the following message header identifiers:

application/x-msdownload;
application/x-iphone;
application/x-compress;
application/mac-binhex40;
application/pkix-crl;
application/x-director;
application/x-cdf;
application/x-gzip;

The virus may use any of the following strings to compose the email message subject line and body text -

Part 1 of 6 Video clipe
Note: forwarded message attached.
begin 664
You Must View This Videoclip!
Miss Lebanon 2006
>> forwarded message
Miss
Re: Sex Video
----- forwarded message -----
My photos
i just any one see my photos.
It's Free :)
Photos
The Best Videoclip Ever
School girl fantasies gone bad
Hot XXX Yahoo Groups
A Great Video
F**kin Kama Sutra pics
ready to be F**KED ;)
give me a kiss
forwarded message attached.
*Hot Movie*
VIDEOS! FREE! (US$ 0,00)
Fw: Picturs
Fw: Funny :)
Fwd: Photo
Fwd: image.jpg
Fw: Sexy
Fw: Real show
Fwd: Crazy illegal Sex!
What?
i send the file.
Hello
i attached the details.
Thank you
the file
i send the details
bye
Word file
hello,
Fw: DSC-00465.jpg
Please see the file.
how are you?
i send the details.

Network spreading routine
The virus will attempt to copy itself to systems across a network into the following share points -

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

The virus may delete the following file from the share location -

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

in order to prevent the pre-existing link file from referencing the non-infectious and actual WinZip32 executable

File Deletion Payload [1]
The virus will attempt to connect to networked computers using the logon name "Administrator". Then the virus will try to delete files associated with Antivirus software installations both locally, and across networked systems. The virus will try to delete from the following local paths and networked systems in shared hard drives -

[Networked systems]
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

[Local]
\Program Files\Symantec\LiveUpdate\*.*
\Program Files\Symantec\Common Files\Symantec Shared\*.*
\Program Files\Norton AntiVirus\*.exe
\Program Files\Alwil Software\Avast4\*.exe
\Program Files\McAfee.com\VSO\*.exe
\Program Files\McAfee.com\Agent\*.*
\Program Files\McAfee.com\shared\*.*
\Program Files\Trend Micro\PC-cillin 2002\*.exe
\Program Files\Trend Micro\PC-cillin 2003\*.exe
\Program Files\Trend Micro\Internet Security\*.exe
\Program Files\NavNT\*.exe
\Program Files\Kaspersky Lab\Kaspersky Anti-Virus Personal\*.ppl
\Program Files\Kaspersky Lab\Kaspersky Anti-Virus Personal\*.exe
\Program Files\Grisoft\AVG7\*.dll
\Program Files\TREND MICRO\OfficeScan\*.dll
\Program Files\Trend Micro\OfficeScan Client\*.exe
\Program Files\HyperTechnologies\Deep Freeze\*.exe

Additionally, the virus will attempt to damage P2P application installations by deleting .DLL component files from various local folders -

\Program Files\DAP\*.dll
\Program Files\BearShare\*.dll
\Program Files\Morpheus\*.dll
\Program Files\LimeWire\LimeWire 4.2.6\LimeWire.jar

File Deletion Payload [2]
This virus will alter data files and archive files after restarting an infected system on the 3rd day of any month. The system also must be on at least 30 minutes or longer for this payload to occur. The payload searches the entire hard drive for files having these extensions -

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

For every file found, the virus will replace the content of the file with the following string which equates to 32 bytes -

DATA Error [47 0F 94 93 F4 K5]

Files which are essentially overwritten with this data require recovery from backup copy.

Application Startup Blocking Routine
This virus may remove registry keys that match the following list of strings - most of these are related to Antivirus software applications -

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

By removing the registry keys, the application referenced in the key fails to load at System startup.

Additional Registry Changes
The virus is coded to register the dropped ActiveX control through changes to the system registry. By creating the following registry entries, the control is considered "safe" and digitally signed -

HKEY_CLASSES_ROOT\Licenses
"(Default)" = Licensing: Copying the keys may be a violation of established copyrights.

HKEY_CLASSES_ROOT\Licenses\096EFC40-6ABF-11cf-850C-08002B30345D
"(Default)" = knsgigmnmngnmnigthmgpninrmumhgkgrlrk

HKEY_CLASSES_ROOT\Licenses\190B7910-992A-11cf-8AFA-00AA00C00905
"(Default)" = gclclcejjcmjdcccoikjlcecoioijjcjnhng

HKEY_CLASSES_ROOT\Licenses\2c49f800-c2dd-11cf-9ad6-0080c7e7b78d
"(Default)" = mlrljgrlhltlngjlthrligklpkrhllglqlrk

HKEY_CLASSES_ROOT\Licenses\4250E830-6AC2-11cf-8ADB-00AA00C00905
"(Default)" = kjljvjjjoquqmjjjvpqqkqmqykypoqjquoun

HKEY_CLASSES_ROOT\Licenses\4D553650-6ABE-11cf-8ADB-00AA00C00905
"(Default)" = gfjmrfkfifkmkfffrlmmgmhmnlulkmfmqkqj

HKEY_CLASSES_ROOT\Licenses\556C75F1-EFBC-11CF-B9F3-00A0247033C4
"(Default)" = xybiedobrqsprbijaegcbislrsiucfjdhisl

HKEY_CLASSES_ROOT\Licenses\57CBF9E0-6AA7-11cf-8ADB-00AA00C00905
"(Default)" = aahakhchghkhfhaamghhbhbhkbpgfhahlfle

HKEY_CLASSES_ROOT\Licenses\5f54e750-ce26-11cf-8e43-00a0c911005a
"(Default)" = mnlnnimimnoiuilnvjkinnkitjwjnimntntm

HKEY_CLASSES_ROOT\Licenses\6FB38640-6AC7-11cf-8ADB-00AA00C00905
"(Default)" = gdjkokgdldikhdddpjkkekgknesjikdkoioh

HKEY_CLASSES_ROOT\Licenses\72E67120-5959-11cf-91F6-C2863C385E30
"(Default)" = ibcbbbebqbdbciebmcobmbhifcmciibblgmf

HKEY_CLASSES_ROOT\Licenses\78E1BDD1-9941-11cf-9756-00AA00C00908
"(Default)" = yjrjvqkjlqqjnqkjvprqsjnjvkuknjpjtoun

HKEY_CLASSES_ROOT\Licenses\7C35CA30-D112-11cf-8E72-00A0C90F26F8
"(Default)" = whmhmhohmhiorhkouimhihihwiwinhlosmsl

HKEY_CLASSES_ROOT\Licenses\899B3E80-6AC6-11cf-8ADB-00AA00C00905
"(Default)" = wjsjjjlqmjpjrjjjvpqqkqmqukypoqjquoun

HKEY_CLASSES_ROOT\Licenses\9E799BF1-8817-11cf-958F-0020AFC28C3B
"(Default)" = uqpqnqkjujkjjjjqwktjrjkjtkupsjnjtoun

HKEY_CLASSES_ROOT\Licenses\B1EFCCF0-6AC1-11cf-8ADB-00AA00C00905
"(Default)" = qqkjvqpqmqjjpqjjvpqqkqmqvkypoqjquoun

HKEY_CLASSES_ROOT\Licenses\BC96F860-9928-11cf-8AFA-00AA00C00905
"(Default)" = mmimfflflmqmlfffrlnmofhfkgrlmmfmqkqj

HKEY_CLASSES_ROOT\Licenses\E32E2733-1BC5-11d0-B8C3-00A0C90DCA10
"(Default)" = kmhfimlflmmfpffmsgfmhmimngtghmoflhsg

The virus also makes other changes such as the following -

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced\
"ShowSuperHidden" = 00, 00, 00, 00

HTT File Modification
The virus will modify the Desktop.htt configuration file which controls how Active Desktop is displayed to user systems. The change is to launch a copy of the virus as C:\WinZip_Tmp.exe whenever Windows loads the Active Desktop (Windows start up). The virus appends JavaScript code to this file -

C:\Documents and Settings\{user}\Application Data\Microsoft\Internet Explorer\Desktop.htt

The code uses an ActiveX control to reference the file "WinZip_Tmp.exe". Additionally, the virus will modify the "desktop.ini" configuration file to point to an infectious "Temp.htt" HTML file to launch the virus.

Description Last Updated Date: Jan 26, 2006
Reference: ID - 143017