RANSOM_CERBER.VSAGD

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites. It may be dropped by other malware.

It uses the Windows Task Scheduler to add a scheduled task that executes the copies it drops.

It modifies the Internet Explorer Zone Settings.

It connects to certain websites to send and receive information. It is capable of encrypting files in the affected system.

Arrival Details

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It may be dropped by the following malware:

• TROJ_CERBER.AL

Installation

This Trojan drops the following copies of itself into the affected system:

• C:\enYXval36CenYXval36C\8ivq.dll
• %User Temp%\8ivq.dll

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It drops the following files:

• C:\enYXval36CenYXval36C\x
• C:\enYXval36CenYXval36C\enYXval36C.vbs
• %User Temp%\a.vbs
• %User Temp%\x
• %Desktop%\_HELP_HELP_HELP_{random}_.png - ransom note
• %Desktop%\_HELP_HELP_HELP_{random}_.hta - ransom note
• %User Temp%\{random name}.bmp - background image
• {folders containing encrypted files}\_HELP_HELP_HELP_{random}_.hta - ransom note
• {folders containing encrypted files}\_HELP_HELP_HELP_{random}_.png - ransom note
• %User Temp%\{random name}\{random name}.tmp

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.. %Desktop% is the desktop folder, where it usually is C:\Documents and Settings\{user name}\Desktop in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\Desktop in Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It uses the Windows Task Scheduler to add a scheduled task that executes the copies it drops.

It adds the following mutexes to ensure that only one of its copies runs at any one time:

• enYXval36C
• nenYXval36C

It injects codes into the following process(es):

• %Windows%\Microsoft.NET\Framework\v2.0.50727\csc.exe
• %Windows%\Microsoft.NET\Framework\v4.0.30319\csc.exe
• %Windows%\SysWow64\WerFault.exe
• %System%\WerFault.exe
• %Windows%\Microsoft.NET\Framework\v2.0.50727\regasm.exe
• %Windows%\Microsoft.NET\Framework\v4.0.30319\regasm.exe

(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.. %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\RunOnce
enYXval36C = C:\enYXval36CenYXval36C\enYXval36C.vbs

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
enYXval36C = C:\enYXval36CenYXval36C\enYXval36C.vbs

The scheduled task executes the malware every:

• 1 minute

Other System Modifications

This Trojan changes the desktop wallpaper by modifying the following registry entries:

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = %User Temp%\{random}.bmp

Process Termination

This Trojan terminates the following processes if found running in the affected system's memory:

• agntsvc.exe agntsvc.exe
• agntsvc.exe encsvc.exe
• agntsvc.exe isqlplussvc.exe
• bitcoin-qt.exe
• dbeng50.exe
• dbsnmp.exe
• fbserver.exe
• firefoxconfig.exe
• msftesql.exe
• mydesktopqos.exe
• mydesktopservice.exe
• mysqld-nt.exe
• mysqld-opt.exe
• mysqld.exe
• ocautoupds.exe
• ocomm.exe
• ocssd.exe
• oracle.exe
• sqbcoreservice.exe
• sqlagent.exe
• sqlbrowser.exe
• sqlservr.exe
• sqlwriter.exe
• synctime.exe
• tbirdconfig.exe
• xfssvccon.exe

Web Browser Home Page and Search Page Modification

This Trojan modifies the Internet Explorer Zone Settings.

Other Details

This Trojan connects to the following website to send and receive information:

• {BLOCKED.{BLOCKED}.56.0/27
• {BLOCKED.{BLOCKED}.56.0/27
• {BLOCKED.{BLOCKED}.56.0/22

It encrypts files with the following extensions:

• .123
• .1cd
• .3dm
• .3ds
• .3fr
• .3g2
• .3gp
• .3pr
• .602
• .7z
• .7zip
• .aac
• .ab4
• .abd
• .acc
• .accdb
• .accde
• .accdr
• .accdt
• .ach
• .acr
• .act
• .adb
• .adp
• .ads
• .aes
• .agdl
• .ai
• .aiff
• .ait
• .al
• .aoi
• .apj
• .apk
• .arc
• .arw
• .ascx
• .asf
• .asm
• .asp
• .aspx
• .asset
• .asx
• .atb
• .avi
• .awg
• .back
• .backup
• .backupdb
• .bak
• .bank
• .bat
• .bay
• .bdb
• .bgt
• .bik
• .bin
• .bkp
• .blend
• .bmp
• .bpw
• .brd
• .bsa
• .bz2
• .c
• .cash
• .cdb
• .cdf
• .cdr
• .cdr3
• .cdr4
• .cdr5
• .cdr6
• .cdrw
• .cdx
• .ce1
• .ce2
• .cer
• .cfg
• .cfn
• .cgm
• .cib
• .class
• .cls
• .cmd
• .cmt
• .config
• .contact
• .cpi
• .cpp
• .cr2
• .craw
• .crt
• .crw
• .cry
• .cs
• .csh
• .csl
• .csr
• .css
• .csv
• .d3dbsp
• .dac
• .das
• .dat
• .db
• .db3
• .db_journal
• .dbf
• .dbx
• .dc2
• .dch
• .dcr
• .dcs
• .ddd
• .ddoc
• .ddrw
• .dds
• .def
• .der
• .des
• .design
• .dgc
• .dgn
• .dif
• .dip
• .dit
• .djv
• .djvu
• .dng
• .doc
• .docb
• .docm
• .docx
• .dot
• .dotm
• .dotx
• .drf
• .drw
• .dtd
• .dwg
• .dxb
• .dxf
• .dxg
• .edb
• .eml
• .eps
• .erbsql
• .erf
• .exf
• .fdb
• .ffd
• .fff
• .fh
• .fhd
• .fla
• .flac
• .flb
• .flf
• .flv
• .forge
• .fpx
• .frm
• .fxg
• .gbr
• .gho
• .gif
• .gpg
• .gray
• .grey
• .groups
• .gry
• .gz
• .h
• .hbk
• .hdd
• .hpp
• .html
• .hwp
• .ibank
• .ibd
• .ibz
• .idx
• .iif
• .iiq
• .incpas
• .indd
• .info
• .info_
• .iwi
• .jar
• .java
• .jnt
• .jpe
• .jpeg
• .jpg
• .js
• .json
• .k2p
• .kc2
• .kdbx
• .kdc
• .key
• .kpdx
• .kwm
• .laccdb
• .lay
• .lay6
• .lbf
• .lck
• .ldf
• .lit
• .litemod
• .litesql
• .lock
• .ltx
• .lua
• .m
• .m2ts
• .m3u
• .m4a
• .m4p
• .m4u
• .m4v
• .ma
• .mab
• .mapimail
• .max
• .mbx
• .md
• .mdb
• .mdc
• .mdf
• .mef
• .mfw
• .mid
• .mkv
• .mlb
• .mml
• .mmw
• .mny
• .money
• .moneywell
• .mos
• .mov
• .mp3
• .mp4
• .mpeg
• .mpg
• .mrw
• .ms11
• .msf
• .msg
• .mts
• .myd
• .myi
• .nd
• .ndd
• .ndf
• .nef
• .nk2
• .nop
• .nrw
• .ns2
• .ns3
• .ns4
• .nsd
• .nsf
• .nsg
• .nsh
• .nvram
• .nwb
• .nx2
• .nxl
• .nyf
• .oab
• .obj
• .odb
• .odc
• .odf
• .odg
• .odm
• .odp
• .ods
• .odt
• .ogg
• .oil
• .omg
• .one
• .onenotec2
• .orf
• .ost
• .otg
• .oth
• .otp
• .ots
• .ott
• .p12
• .p7b
• .p7c
• .pab
• .pages
• .paq
• .pas
• .pat
• .pbf
• .pcd
• .pct
• .pdb
• .pdd
• .pdf
• .pef
• .pem
• .pfx
• .php
• .pif
• .pl
• .plc
• .plus_muhd
• .pm
• .pm!
• .pmi
• .pmj
• .pml
• .pmm
• .pmo
• .pmr
• .pnc
• .pnd
• .png
• .pnx
• .pot
• .potm
• .potx
• .ppam
• .pps
• .ppsm
• .ppsx
• .ppt
• .pptm
• .pptx
• .prf
• .private
• .ps
• .psafe3
• .psd
• .pspimage
• .pst
• .ptx
• .pub
• .pwm
• .py
• .qba
• .qbb
• .qbm
• .qbr
• .qbw
• .qbx
• .qby
• .qcow
• .qcow2
• .qed
• .qtb
• .r3d
• .raf
• .rar
• .rat
• .raw
• .rb
• .rdb
• .re4
• .rm
• .rtf
• .rvt
• .rw2
• .rwl
• .rwz
• .s3db
• .safe
• .sas7bdat
• .sav
• .save
• .say
• .sch
• .sd0
• .sda
• .sdb
• .sdf
• .secret
• .sh
• .sldm
• .sldx
• .slk
• .slm
• .sql
• .sqlite
• .sqlite-shm
• .sqlite-wal
• .sqlite3
• .sqlitedb
• .sr2
• .srb
• .srf
• .srs
• .srt
• .srw
• .st4
• .st5
• .st6
• .st7
• .st8
• .stc
• .std
• .sti
• .stl
• .stm
• .stw
• .stx
• .svg
• .swf
• .sxc
• .sxd
• .sxg
• .sxi
• .sxm
• .sxw
• .tar
• .tax
• .tbb
• .tbk
• .tbn
• .tex
• .tga
• .tgz
• .thm
• .tif
• .tiff
• .tlg
• .tlx
• .txt
• .uop
• .uot
• .upk
• .usr
• .vb
• .vbox
• .vbs
• .vdi
• .vhd
• .vhdx
• .vmdk
• .vmsd
• .vmx
• .vmxf
• .vob
• .vpd
• .vsd
• .wab
• .wad
• .wallet
• .war
• .wav
• .wb2
• .wk1
• .wks
• .wma
• .wmf
• .wmv
• .wpd
• .wps
• .x11
• .x3f
• .xis
• .xla
• .xlam
• .xlc
• .xlk
• .xlm
• .xlr
• .xls
• .xlsb
• .xlsm
• .xlsx
• .xlt
• .xltm
• .xltx
• .xlw
• .xml
• .xps
• .xxx
• .ycbcra
• .yuv
• .zip

It requires the following additional components to properly run:

• x - encrypted component

It renames encrypted files using the following names:

• {10 Random Characters}.{4 Random}

It does the following:

• It avoids encrypting files in the following paths:
  • \$getcurrent\
  • \$recycle.bin\
  • \$windows.~bt\
  • \$windows.~ws\
  • \Boot\
  • \Documents and Settings\All Users\
  • \Documents and Settings\Default User\
  • \Documents and Settings\Localservice\
  • \Documents and Settings\Networkservice\
  • \Intel\
  • \Msocache\
  • \Perflogs\
  • \Program Files (x86)\
  • \Program Files\
  • \Programdata\
  • \Recovery\
  • \Recycled\
  • \Recycler\
  • \System Volume Information\
  • \Temp\
  • \Windows.old\
  • \Windows10upgrade\
  • \Windows\
  • \Winnt\
  • \AppData\Local\
  • \AppData\LocalLow\
  • \AppData\Roaming\
  • \Local Settings\
  • \Public\Music\Sample Music\
  • \Public\Pictures\Sample Pictures\
  • \Public\Videos\Sample Videos\
  • \Tor Browser\
• It terminates itself if found running in any of the following countries:
  • Armenia
  • Azerbaijan
  • Belarus
  • Georgia
  • Kazakhstan
  • Kyrgyzstan
  • Moldova
  • Russia
  • Tajikistan
  • Turkmenistan
  • Ukraine
  • Uzbekistan
• It is configured to target related files under the following folders:
  • \bitcoin\
  • \excel\
  • \microsoft sql server\
  • \microsoft\excel\
  • \microsoft\microsoft sql server\
  • \microsoft\office\
  • \microsoft\onenote\
  • \microsoft\outlook\
  • \microsoft\powerpoint\
  • \microsoft\word\
  • \office\
  • \onenote\
  • \outlook\
  • \powerpoint\
  • \steam\
  • \the bat!\
  • \thunderbird\
  • \word\
• This ransomware changes the wallpaper with the following image:

  

• It displays the ransom note with the following content:

  

• It speaks the following text using text-to-speech application:
  • "Attention! Attention! Attention! Your documents, photos, databases and other important files have been encrypted!"
• It avoids encrypting the following files:
  • bootsect.bak
  • iconcache.db
  • ntuser.dat
  • thumbs.db
• It avoids encrypting files with the following extensions:
  • .bat
  • .cmd
  • .com
  • .cpl
  • .dll
  • .exe
  • .hta
  • .msc
  • .msi
  • .msp
  • .pif
  • .scf
  • .scr
  • .sys

It is capable of encrypting files in the affected system.

NOTES:

This malware loads x into its memory and decrypts it. After decryption, it will perform its malicious routines.

It terminates itself if any of the following processes are found:

• msconfig.exe
• wireshark.exe
• spideragent.exe

It terminates itself if any of the following folders are found:

• C:\Program Files\Bitdefender
• C:\Program Files (x86)\Norton Security
• C:\Program Files\Norton Security
• C:\Program Files\Trend Micro

It shutdowns the computer if any of the following files and folders are found:

• C:\Program Files (x86)\AVG\Framework\Common\avguix.exe
• C:\Program Files\AVG\Framework\Common\avguix.exe
• C:\Program Files (x86)\Kaspersky Lab