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  3. VBS.Crigent

VBS.Crigent

Risk Level 1: Very Low

Discovered:
April 15, 2014
Updated:
April 18, 2014 10:53:31 AM
Type:
Trojan
Systems Affected:
Windows 2000, Windows 7, Windows 95, Windows 98, Windows Me, Windows NT, Windows Server 2003, Windows Server 2008, Windows Vista, Windows XP
The Trojan may be downloaded or dropped by other malware.

Once executed, the Trojan creates the following hidden folder:
%UserProfile%\Application Data\[UUID]

The Trojan also creates the following registry subkey:
HKEY_CURRENT_USER\Software\Microsoft\[UUID]1

It then downloads an archive file from one of the following remote locations:
  • i.vankin.de
  • gg.ibiz.cc

The Trojan then saves the archive file to the following location:
%UserProfile%\Application Data\[UUID]\roaming.zip

Next, the Trojan extracts the following files from the archive file before deleting it:
  • %UserProfile%\Application Data\[UUID]\tor.exe
  • %UserProfile%\Application Data\[UUID]\polipo.exe

It then uses the extracted files to connect to the Tor network.

The Trojan may also execute commands stored in the following registry subkey:
HKEY_CURRENT_USER\Software\Microsoft\[UUID]1

The Trojan then opens a back door on the compromised computer and retrieves commands from the following remote location:
[http://]powerwormjqj42hu.onion/get[REMOVED]?s=autorun&uid=[UUID]

The Trojan may download and execute a script from the above location.

The script encrypts files on the compromised computer and instructs the user on how to decrypt them.

When the script is executed, it generates the following password:
[UUID][60 RANDOM CHARACTERS]

The script uses RSA-4096 encryption to encrypt the generated password and then saves it in the following location:
HKEY_CURRENT_USER\Software\Microsoft\[UUID]0

The script saves a partial user instructions script in the following location:
HKEY_CURRENT_USER\Software\Microsoft\[UUID]1

The script searches for files with specific extensions (see below for the extensions list) and encrypts them using RinjdaelManaged with the previously generated password.

The script encrypts the files in place and moves them to the following location:
[ORIGINAL FILE NAME].poshkoder

The script saves the encrypted file list, the user instruction script, and the encrypted password to the following location:
UnlockFiles.vbs

NOTE:
If the registry keys are not found, the script displays a message asking to be run on a computer with encrypted files.

When UnlockFiles.vbs is run, it sends the data necessary for decryption to the following location:
[http://]poshkodervhkj22w.onion/firsts[REMOVED]

It will also provide the user with decryption instructions through pop-up messages.

Extensions list:
  • 1cd
  • 3d
  • 3d4
  • 3df8
  • 3g2
  • 3gp
  • 3gp2
  • 3mm
  • 7z
  • 8ba
  • 8bc
  • 8be
  • 8bf
  • 8bi8
  • 8bl
  • 8bs
  • 8bx
  • 8by
  • 8li
  • aac
  • abk
  • abw
  • ac3
  • ace
  • act
  • ade
  • adi
  • adpb
  • adr
  • adt
  • aim
  • aip
  • ais
  • amf
  • amr
  • amu
  • amx
  • amxx
  • ans
  • ap
  • ape
  • api
  • arc
  • ari
  • arj
  • aro
  • arr
  • asa
  • asc
  • ascx
  • ase
  • ashx
  • asmx
  • asp
  • aspx
  • asr
  • atom
  • avi
  • avs
  • bdp
  • bdr
  • bi8
  • bib
  • bic
  • big
  • bik
  • bin
  • bkf
  • blp
  • bmc
  • bmf
  • bml
  • bmp
  • boc
  • bp2
  • bp3
  • bpl
  • bsp
  • cag
  • cam
  • cap
  • car
  • cbr
  • cbz
  • cc
  • ccd
  • cch
  • cd
  • cdr
  • cer
  • cfg
  • cgf
  • chk
  • clr
  • cms
  • cod
  • col
  • cp
  • cpp
  • crd
  • crt
  • cs
  • csi
  • cso
  • css
  • ctt
  • cty
  • cwf
  • dal
  • dap
  • db
  • dbb
  • dbx
  • dcp
  • dcu
  • ddc
  • ddcx
  • dem
  • dev
  • dex
  • dic
  • dif
  • dii
  • dir
  • disk
  • divx
  • diz
  • djvu
  • dmg
  • dng
  • dob
  • doc
  • docm
  • docx
  • dot
  • dotm
  • dotx
  • dox
  • dpk
  • dpl
  • dpr
  • dsk
  • dsp
  • dvd
  • dvi
  • dvx
  • dxe
  • elf
  • eps
  • eql
  • err
  • euc
  • evo
  • ex
  • f90
  • faq
  • fcd
  • fdr
  • fds
  • ff
  • fla
  • flp
  • flv
  • for
  • fpp
  • gam
  • gif
  • grf
  • gthr
  • gz
  • gzig
  • h3m
  • h4r
  • htm
  • html
  • idx
  • img
  • ink
  • ipa
  • iso
  • isu
  • isz
  • itdb
  • itl
  • iwd
  • jar
  • jav
  • java
  • jc
  • jgz
  • jif
  • jiff
  • jpc
  • jpeg
  • jpf
  • jpg
  • jpw
  • js
  • kmz
  • kwd
  • lbi
  • lcd
  • lcf
  • ldb
  • lgp
  • lnk
  • lp2
  • ltm
  • ltr
  • lvl
  • mag
  • man
  • map
  • max
  • mbox
  • mbx
  • mcd
  • md0
  • md1
  • md2
  • md3
  • md3
  • mdf
  • mdl
  • mdn
  • mds
  • mic
  • mid
  • midi
  • mip
  • mlx
  • mm6
  • mm7
  • mm8
  • mmf
  • mod
  • moz
  • mp1
  • mp3
  • mp4
  • mpa
  • mpga
  • mpu
  • msg
  • msi
  • msp
  • mxp
  • nav
  • ncd
  • nds
  • nfo
  • now
  • nrg
  • nri
  • nrt
  • odc
  • odf
  • odi
  • odm
  • odp
  • ods
  • oft
  • oga
  • ogg
  • opf
  • owl
  • oxt
  • pab
  • pak
  • pbf
  • pbp
  • pbs
  • pcv
  • pdd
  • pdf
  • php
  • pkb
  • pkh
  • pl
  • plc
  • pli
  • pm
  • png
  • pot
  • potm
  • potx
  • ppd
  • ppf
  • pps
  • ppsm
  • ppsx
  • ppt
  • pptm
  • pptx
  • prc
  • prt
  • psa
  • psd
  • puz
  • pwf
  • pwi
  • pxp
  • qdf
  • qel
  • qif
  • qpx
  • qtiq
  • qtq
  • qtr
  • r00
  • r01
  • r02
  • r03
  • ra
  • ram
  • rar
  • raw
  • res
  • rev
  • rgn
  • rnc
  • rng
  • rrt
  • rsrc
  • rsw
  • rte
  • rtf
  • rts
  • rtx
  • rum
  • run
  • rv
  • sad
  • saf
  • sav
  • scm
  • scn
  • scx
  • sdb
  • sdc
  • sdn
  • sds
  • sdt
  • sen
  • sfs
  • sfx
  • sh
  • shar
  • shr
  • shw
  • slt
  • snp
  • so
  • spr
  • sql
  • sqx
  • srf
  • srt
  • ssa
  • std
  • stt
  • stx
  • sud
  • svi
  • svr
  • swd
  • swf
  • t01
  • t03
  • t05
  • tbz2
  • tch
  • tcx
  • text
  • tg
  • thmx
  • tif
  • tiff
  • tlz
  • tpu
  • tpx
  • trp
  • tu
  • tur
  • txd
  • txf
  • txt
  • uax
  • udf
  • umx
  • unr
  • unx
  • uop
  • upoi
  • url
  • usa
  • usx
  • ut2
  • ut3
  • utc
  • utx
  • uvx
  • uxx
  • val
  • vc
  • vcd
  • vdo
  • ver
  • vhd
  • vmf
  • vmt
  • vsi
  • vtf
  • w3g
  • w3x
  • wad
  • war
  • wav
  • wave
  • waw
  • wbk
  • wdgt
  • wks
  • wm
  • wma
  • wmd
  • wmdb
  • wmmp
  • wmv
  • wmx
  • wow
  • wpk
  • wpl
  • wsh
  • wtd
  • wtf
  • wvx
  • xl
  • xla
  • xlam
  • xlc
  • xll
  • xlm
  • xlr
  • xls
  • xlsb
  • xlsm
  • xlsx
  • xltx
  • xlv
  • xlwx
  • xml
  • xpi
  • xpt
  • xvid
  • xwd
  • yab
  • yps
  • z02
  • z04
  • zap
  • zip
  • zipx
  • zoo

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: Ling Zhou
Summary| Technical Details| Removal

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