Discovered: March 31, 2005
Updated: February 13, 2007 12:36:07 PM
Also Known As: W32.Sober.N@mm
Type: Worm
Systems Affected: Windows 2000, Windows 95, Windows 98, Windows Me, Windows NT, Windows Server 2003, Windows XP
When Trojan.Ascetic.B is executed, it performs the following actions:
- Copies itself as the following:
- %Windir%\addins\explorer\csrss.exe
- %System%\[Random file name].exe
- %Temp%\_[Random file name].exe
Notes:
- %Windir% is a variable that refers to the Windows installation folder. By default, this is C:\Windows or C:\Winnt.
- %System% is a variable that refers to the System folder. By default this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).
- %Temp% is a variable that refers to the Windows temporary folder. By default, this is C:\Windows\TEMP (Windows 95/98/Me/XP) or C:\WINNT\Temp (Windows NT/2000).
- Creates the following files:
- %Windir%\addins\explorer\infectok.iok
- %Windir%\addins\explorer\jjfggggr.oou (A text file containing email addresses gathered from the compromised computer.)
- %System%\nonrunso.ber
- %System%\adcmmmmq.hjg
- %System%\xcvfpokd.tqa
- %System%\stopruns.zhz
- Adds the value:
" SystemDriver" = "%Windir%\addins\explorer\csrss.exe"
to the registry subkey:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
so that the Trojan is executed every time Windows starts.
- Adds the value:
"_SystemDriver" = "%Windir%\addins\explorer\csrss.exe"
to the registry subkey:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
so that the Trojan is executed every time Windows starts.
- Registers itself as a service named wscsvc.
- Attempts to download the file people.freenet.de/wlfkillscx/djhre.sss and saves it locally as systemxx.exe. The Trojan then executes the downloaded file.
- Attempts to use one of the following DNS servers:
- 128.135.5.5
- 202.89.131.4
- 219.127.89.34
- 129.115.102.150
- 38.9.211.2
- 134.94.80.2
- 130.149.2.12
- 150.203.22.28
- 131.215.254.100
- 128.194.254.2
- 216.194.225.70
- 4.2.2.3
- 195.185.185.195
- 209.68.2.46
- 129.186.1.200
- 198.6.1.2
- 131.243.64.3
- 24.93.40.33
- 195.182.96.29
- 192.90.162.8
- 158.43.128.1
- 128.35.253.3
- 61.95.134.168
- 200.74.214.246
- 204.117.214.10
- 194.25.2.129
- 203.162.0.11
- 210.66.241.1
- 217.237.150.225
- 217.237.151.161
- 128.9.128.127
- 151.201.0.39
- 209.253.113.2
- 213.239.234.108
- 62.156.146.242
- 166.60.12.11
- 207.69.188.186
- 207.217.120.43
- 129.187.10.25
- 200.52.83.103
- 129.187.16.1
- 141.40.10.35
- 213.218.170.6
- 203.50.0.137
- 212.242.88.2
- 193.158.124.143
to get the IP address of the following:
- microsoft.com
- bigfoot.com
- yahoo.com
- t-online.de
- google.com
- hotmail.com
- Ends processes containing any of the following strings:
- gcip
- giantanti
- stinger
- hijack
- sober
- rclean
- Attempts to connect to the following hosts:
- Rolex.PeachNet.edu
- ntp3.fau.de
- utcnist.colorado.edu
- sundial.columbia.edu
- ri.ntp.carnet.hr
- ntp-sop.inria.fr
- rolex.usg.edu
- time.xmission.com
- ntp.massayonet.com.br
- ntp-1.ece.cmu.edu
- ntp2a.mcc.ac.uk
- ntp.lth.se
- cuckoo.nevada.edu
- ntp-2.ece.cmu.edu
- time.kfki.hu
- ntp.pads.ufrj.br
- time-ext.missouri.edu
- ntp1.arnes.si
- time.chu.nrc.ca
- time-server.ndo.com
- May display one of the following fake error messages:
Title: Winsock 2.0 Error
Body: STOP:0x10020AF {Unknown_blocking}
Possible Reason: Your "Firewall" is blocking one or more System files
Check the "Winsock Error Log File" on: C:\WinsockError_log.txt
Title: Windows
Body: This File is not supported by Microsoft
Title: Windows System
Body: File-Header not found
- May create a non-malicious file named C:\WinsockError_log.txt, which contains fake error logs.
- Collects email addresses from files with the following extensions:
- .exe
- .msi
- .scr
- .com
- .bat
- .pif
- .jpg
- .mp3
- .mp4
- .jpeg
- .png
- .avi
- .mpg
- .mpeg
- .cmd
- Stores the collected email addresses in the file %Windir%\addins\explorer\jjfggggr.oou.
- Sends emails to some predefined email addresses with the following characteristics:
From: [%from%][%domain1%][%domain2%]
where [%from%] is one of the following:
- micha-bedriks
- t.werter
- m-poltrock
- homepage-carsten
- schwan_nikki
- harald-lobers
[%domain1%] is one of the following:
- @gmx.
- @web.
- @arcor
- @freenet
[%domain2%] is one of the following:
- de
- at
- ch
- com
- net
To: [%to%][%domain1%][%domain2%]
where [%to%] is one of the following:
- Heike_Jonnas
- Nicole_Joo
- Bendriks-Micha
- eli.schnuti
- Thomas_Werter
- M.Poltrok
- schenkler-carsti
- Nikki.Schwan
Subject: [randomly generated text]
Message: [the email addresses that the Trojan harvested from the compromised computer]
- Attempts to dial any available dial-up connection, if the compromised computer doesn't have an active Internet connection.
Recommendations
Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":
- Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
- Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
- Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
- Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
- Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
- Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
- If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
- Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
- Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
- Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
- Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
- If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
- For further information on the terms used in this document, please refer to the Security Response glossary.
Writeup By: Peter Ferrie
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