RANSOM_CERBER.VSAGD

 Analysis by: John Anthony Banes

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware, Downloaded from the Internet


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.

  TECHNICAL DETAILS

File Size:

11,159,656 bytes

File Type:

DLL

Memory Resident:

Yes

Initial Samples Received Date:

20 Feb 2017

Payload:

Encrypts files, Connects to URLs/IPs, Drops files

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

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.232.05

FIRST VSAPI PATTERN DATE:

20 Feb 2017

VSAPI OPR PATTERN File:

13.233.00

VSAPI OPR PATTERN Date:

21 Feb 2017

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

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

Step 5

Delete the Scheduled Tasks added by this malware/grayware

[ Learn More ]

To delete the added Scheduled Task file:

For Windows 2000, Windows XP, and Windows Server 2003:

  1. Open the Windows Scheduled Tasks. To do this, click Start>Programs>Accessories>System Tools>Scheduled Tasks.
  2. Double-click on a .JOB file.
  3. Check if the malware path and file name exists in the .JOB file. To do this, check the value in the Run field.
  4. If found, select the .JOB file then press SHIFT+DELETE to permanently delete the file.
  5. Repeat the steps above for the remaining .JOB files.

For Windows Vista, Windows 7, Windows Server 2008, Windows 8, Windows 8.1, and Windows Server 2012:

  1. Open the Windows Task Scheduler. To do this:
    • On Windows Vista, Windows 7, and Windows Server 2008, click Start, type taskschd.msc in the Search input field, then press Enter.
    • On Windows 8, Windows 8.1, and Windows Server 2012, right-click on the lower left corner of the screen, click Run, type taskschd.msc, then press Enter.
  2. In the left panel of the Task Scheduler Window, click Task Scheduler Library.
  3. In the upper-middle panel, click a Task.
  4. In the lower middle panel, click the Actions tab
  5. Check if the malware path and file name exists in the task. To do this, check the value in the Details column under the Actions tab.
  6. If found, select the task and press DELETE and click Yes to delete the task.
  7. Repeat the steps above for the remaining tasks.

Step 6

Search and delete these files

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %Desktop%\_HELP_HELP_HELP_{random}_.png
  • %Desktop%\_HELP_HELP_HELP_{random}_.hta
  • %User Temp%\{random name}.bmp
  • {folders containing encrypted files}\_HELP_HELP_HELP_{random}_.hta
  • {folders containing encrypted files}\_HELP_HELP_HELP_{random}_.png
  • %User Temp%\{random name}\{random name}.tmp
  • C:\enYXval36CenYXval36C\x
  • C:\enYXval36CenYXval36C\enYXval36C.vbs
  • %User Temp%\a.vbs
  • %User Temp%\x

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_CERBER.VSAGD. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.

Step 8

Reset your Desktop properties

[ Learn More ]

Step 9

Reset Internet security settings

[ Learn More ]

Step 10

Restore encrypted files from backup.


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