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  3. Trojan.Gpcoder.E

Trojan.Gpcoder.E

Risk Level 1: Very Low

Discovered:
July 17, 2007
Updated:
August 22, 2012 8:58:56 AM
Also Known As:
Virus.Win32.Gpcode.ai [Kaspersky], Win32/Kollah.AB [Computer Associates], Troj/GPCoder-G [Sophos], Sinowal.FY [Panda Software], PWS-JT [McAfee]
Type:
Trojan
Infection Length:
58,368 bytes
Systems Affected:
Windows XP, Windows NT, Windows Server 2003, Windows 2000
When the Trojan is executed, it creates the following mutex to ensure that only one copy of the threat is running on the computer:
__SYSTEM__64AD0625__

Next, the Trojan copies itself to the following location and appends a random amount of data to the file in order to have a random size:
%System%\ntos.exe

It checks for the presence of the following firewall programs:
  • OUTPOST.EXE
  • CCPROXY.EXE

If present, the threat copies itself to the %System% folder but postpones its malicious activity until the computer restarts.

It then gathers the following information from the compromised computer:
  • OS version
  • Presence of Service Pack 2
  • Language of the system

It creates the following folder with system and hidden attributes:
%System%\wsnpoem

The Trojan then creates the following file, which is used to save gathered information:
%System%\wsnpoem\audio.dll

It also creates the following file, which is used to store the encrypted configuration of the Trojan:
%System%\wsnpoem\video.dll

Next, the Trojan modifies the following registry entry so that it executes whenever Windows starts:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\"Userinit" = "%System%\userinit.exe, %System%\ntos.exe"

It may also create the following registry entries so that it executes whenever Windows starts:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run\"userinit" = "%System%\ntos.exe"
HKEY_USERS\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Run\"userinit" = "%System%\ntos.exe"

Next, it injects malicious code into the following running processes:
  • WINLOGON.EXE
  • SVCHOST.EXE

The Trojan attempts to create malicious threads in all running processes except for the following one:
CSRSS.EXE

The injected code will prevent the removal of the Trojan by blocking access to deletion of all of the malicious files and by regenerating all of the registry subkeys associated with the Trojan when they are deleted.

The Trojan then hooks certain system functions using usermode rootkit techniques to ensure that its code gets injected into each process.

The Trojan attempts to gain control of network functionalities and to steal sensitive information.

The Trojan may perform the following actions:
  • Intercept network traffic
  • Redirect traffic

Next, it may add the following registry entry as an infection marker for the compromised computer:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Network\"UID" = "[COMPUTER NAME]_[UNIQUE ID]"

The Trojan then opens a back door on TCP Port 6081.

If the system date is after July 10, 2007, it starts the encryption routine of files present on the computer.

It creates the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\"WinCode" = "[ENCRYPTION KEY]"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\"Win32" = "[MAIL FLAG VALUE]"

Where:
[ENCRYPTION KEY] is a random generated unique 4-bytes key for the specific compromised computer.
[MAIL FLAG VALUE] is a random chosen number between 1 and 4 used to select the email address of the attacker.

Next, it scans for files on all drives from A through W, excluding CD-ROM drives and the root of drives. If a drive is found, it searches sequentially by two drive letters for the next drive. For example, if drive C is not a CD-ROM drive, it searches drive E for files.

The Trojan searches for files with the following extensions:
  • .12m
  • .3ds
  • .3dx
  • .4ge
  • .4gl
  • .7z
  • .a86
  • .abc
  • .acd
  • .ace
  • .act
  • .ada
  • .adi
  • .aex
  • .af3
  • .afd
  • .ag4
  • .ai
  • .aif
  • .aifc
  • .aiff
  • .ain
  • .aio
  • .ais
  • .akf
  • .alv
  • .amp
  • .ans
  • .ap
  • .apa
  • .apo
  • .app
  • .arc
  • .arh
  • .arj
  • .arx
  • .asc
  • .asm
  • .ask
  • .au
  • .bak
  • .bas
  • .bb
  • .bcb
  • .bcp
  • .bdb
  • .bh
  • .bib
  • .bpr
  • .bsa
  • .btr
  • .bup
  • .bwb
  • .bz
  • .bz2
  • .c86
  • .cac
  • .cbl
  • .cc
  • .cdb
  • .cdr
  • .cgi
  • .cmd
  • .cnt
  • .cob
  • .col
  • .cpp
  • .cpt
  • .crp
  • .cru
  • .csc
  • .css
  • .csv
  • .ctx
  • .cvs
  • .cwb
  • .cwk
  • .cxe
  • .cxx
  • .cyp
  • .db
  • .db0
  • .db1
  • .db2
  • .db3
  • .db4
  • .dba
  • .dbb
  • .dbc
  • .dbd
  • .dbe
  • .dbf
  • .dbk
  • .dbm
  • .dbo
  • .dbq
  • .dbt
  • .dbx
  • .dfm
  • .djvu
  • .dic
  • .dif
  • .dm
  • .dmd
  • .doc
  • .dok
  • .dot
  • .dox
  • .dsc
  • .dwg
  • .dxf
  • .dxr
  • .eps
  • .exp
  • .fas
  • .fax
  • .fdb
  • .fla
  • .flb
  • .frm
  • .fm
  • .fox
  • .frm
  • .frt
  • .frx
  • .fsl
  • .gtd
  • .gif
  • .gz
  • .gzip
  • .ha
  • .hh
  • .hjt
  • .hog
  • .hpp
  • .htm
  • .html
  • .htx
  • .ice
  • .icf
  • .inc
  • .ish
  • .iso
  • .jar
  • .jad
  • .java
  • .jpg
  • .jpeg
  • .js
  • .jsp
  • .key
  • .kwm
  • .lst
  • .lwp
  • .lzh
  • .lzs
  • .lzw
  • .ma
  • .mak
  • .man
  • .maq
  • .mar
  • .mbx
  • .mdb
  • .mdf
  • .mid
  • .mo
  • .myd
  • .obj
  • .old
  • .p12
  • .pak
  • .pas
  • .pdf
  • .pem
  • .pfx
  • .php
  • .php3
  • .php4
  • .pgp
  • .pkr
  • .pl
  • .pm3
  • .pm4
  • .pm5
  • .pm6
  • .png
  • .ppt
  • .pps
  • .prf
  • .prx
  • .ps
  • .psd
  • .pst
  • .pw
  • .pwa
  • .pwl
  • .pwm
  • .pwp
  • .pxl
  • .py
  • .rar
  • .res
  • .rle
  • .rmr
  • .rnd
  • .rtf
  • .safe
  • .sar
  • .skr
  • .sln
  • .swf
  • .sql
  • .tar
  • .tbb
  • .tex
  • .tga
  • .tgz
  • .tif
  • .tiff
  • .txt
  • .vb
  • .vp
  • .wps
  • .xcr
  • .xls
  • .xml
  • .zip

When a file is found, the Trojan encrypts it with a custom encryption algorithm by using the generated key. The first bytes of the encrypted files contain the string "GLAMOUR" followed by the encrypted data.

Next, the Trojan creates the following file in each folder where a file has been encrypted:
read_me.txt

The file contains the following message:

Hello, your files are encrypted with RSA-4096 algorithm ([http://]en.wikipedia.org/wiki/R[REMOVED]).
You will need at least few years to decrypt these files without our software.
All your private information for last 3 months were collected and sent to us.
To decrypt your files you need to buy our software. The price is $300.
To buy our software please contact us at: [MAIL ADDRESS] and provide us your personal code [PERSONAL CODE].
After successful purchase we will send your decrypting tool, and your private information
will be deleted from our system.
If you will not contact us until 07/15/2007 your private information will be shared and you will lost all your data.

Glamorous team

Where:

[MAIL ADDRESS] is one the following email addresses chosen according to the [MAIL FLAG VALUE] number:
  • kiloglamour@gmail.com
  • tristanniglam@gmail.com
  • oxyglamour@gmail.com
  • glamourpalace@gmail.com

[PERSONAL CODE] is a decimal number converted from the [ENCRYPTION KEY] value.

The Trojan attempts to send and receive data from the following remote host:
[http://]martin-golf.net/pajero/cfg[REMOVED]

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: Elia Florio
Summary| Technical Details| Removal

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