Analysis by: Anthony Joe Melgarejo

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Spammed via email, Downloaded from the Internet

This Trojan may be unknowingly downloaded by a user while visiting malicious websites.

It connects to certain websites to send and receive information. It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size: 174,082 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 02 Dec 2015
Payload: Connects to URLs/IPs, Displays graphics/image, Encrypts files

Arrival Details

This Trojan may be unknowingly downloaded by a user while visiting malicious websites.

Installation

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

  • %Application Data%\UpdSysDrv32Xz32\{8 random letters}.exe

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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:

  • %Application Data%\UpdSysDrv32Xz32\UpdSyz32.bmp
  • %System Root%\HELP_DECRYPT.jpg
  • %System Root%\HELP_DECRYPT.txt
  • %Desktop%\HELP_DECRYPT.jpg
  • %Desktop%\HELP_DECRYPT.txt
  • %User Profile%\My Documents\HELP_DECRYPT.jpg
  • %User Profile%\My Documents\HELP_DECRYPT.txt
  • {User Music}\HELP_DECRYPT.jpg
  • {User Music}\HELP_DECRYPT.txt
  • {User Pictures}\HELP_DECRYPT.jpg
  • {User Pictures}\HELP_DECRYPT.txt
  • {User Videos}\HELP_DECRYPT.jpg
  • {User Videos}\HELP_DECRYPT.txt

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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.. %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %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.. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

It adds the following processes:

  • svchost.exe

It creates the following folders:

  • %Application Data%\UpdSysDrv32Xz32

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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 injects codes into the following process(es):

  • created svchost.exe

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\Run
UpdSysDrvX32z32 = "%Application Data%\UpdSysDrv32Xz32\{8 random letters}.exe"

Other System Modifications

This Trojan adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows
UpdSysDrvNamxz32 = "{dropped copy's file name}"

HKEY_CURRENT_USER\Software\Microsoft\
Windows
UpdSysDrvz23 = "{initial malware path}"

HKEY_CURRENT_USER\Software\Microsoft\
Windows
TRUECRT32 = "TrueBOSS"

It changes the desktop wallpaper by modifying the following registry entries:

HKEY_CURRENT_USER\Control Panel\Desktop
WallpaperStyle = "0"

(Note: The default value data of the said registry entry is {user preference}.)

HKEY_CURRENT_USER\Control Panel\Desktop
TileWallpaper = "0"

(Note: The default value data of the said registry entry is {user preference}.)

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = %Application Data%\UpdSysDrv32Xz32\UpdSysDrz32.jpg

(Note: The default value data of the said registry entry is {user preference}.)

It sets the system's desktop wallpaper to the following image:

Download Routine

This Trojan connects to the following URL(s) to download its component file(s):

  • http://{BLOCKED}starter.com/img.jpg

It saves the files it downloads using the following names:

  • %Application Data%\UpdSysDrv32Xz32\UpdSysDrz32.jpg - ransom note

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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.)

Other Details

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

  • http://{BLOCKED}-starter.com/upd.php

It encrypts files with the following extensions:

  • .sql
  • .mp4
  • .7z
  • .rar
  • .m4a
  • .wma
  • .avi
  • .wmv
  • .csv
  • .d3dbsp
  • .zip
  • .sie
  • .unrec
  • .scan
  • .sum
  • .t13
  • .t12
  • .qdf
  • .gdb
  • .tax
  • .pkpass
  • .bc6
  • .bc7
  • .bkp
  • .qic
  • .bkf
  • .sidn
  • .sidd
  • .mddata
  • .itl
  • .itdb
  • .icxs
  • .hvpl
  • .hplg
  • .hkdb
  • .mdbackup
  • .syncdb
  • .gho
  • .cas
  • .svg
  • .map
  • .wmo
  • .itm
  • .sb
  • .fos
  • .mov
  • .vdf
  • .ztmp
  • .sis
  • .sid
  • .ncf
  • .menu
  • .layout
  • .dmp
  • .blob
  • .esm
  • .vcf
  • .vtf
  • .dazip
  • .fpk
  • .mlx
  • .kf
  • .iwd
  • .vpk
  • .tor
  • .psk
  • .rim
  • .w3x
  • .fsh
  • .ntl
  • .arch00
  • .lvl
  • .snx
  • .cfr
  • .ff
  • .vpp_pc
  • .lrf
  • .m2
  • .mcmeta
  • .vfs0
  • .mpqge
  • .kdb
  • .db0
  • .dba
  • .rofl
  • .hkx
  • .bar
  • .upk
  • .das
  • .iwi
  • .litemod
  • .asset
  • .forge
  • .ltx
  • .bsa
  • .apk
  • .re4
  • .sav
  • .lbf
  • .slm
  • .bik
  • .epk
  • .rgss3a
  • .pak
  • .big
  • .wallet
  • .wotreplay
  • .xxx
  • .desc
  • .m3u
  • .flv
  • .js
  • .css
  • .rb
  • .png
  • .txt
  • .p7c
  • .p7b
  • .p12
  • .pfx
  • .pem
  • .crt
  • .cer
  • .der
  • .x3f
  • .srw
  • .pef
  • .ptx
  • .r3d
  • .rw2
  • .rwl
  • .raw
  • .raf
  • .orf
  • .nrw
  • .mrwref
  • .mef
  • .erf
  • .kdc
  • .dcr
  • .cr2
  • .crw
  • .bay
  • .sr2
  • .srf
  • .arw
  • .3fr
  • .dng
  • .jpe
  • .jpg
  • .cdr
  • .indd
  • .ai
  • .eps
  • .pdf
  • .pdd
  • .psd
  • .dbf
  • .mdf
  • .wb2
  • .rtf
  • .wpd
  • .dxg
  • .xf
  • .dwg
  • .pst
  • .accdb
  • .mdb
  • .ppt
  • .xlk
  • .xls
  • .wps
  • .doc
  • .odb
  • .odc
  • .odm
  • .odp
  • .odt
  • .dx
  • .mrw
  • .nef
  • .tiff
  • .bd
  • .tar
  • .gz
  • .backup
  • .mkv
  • .bmp
  • .dot
  • .xml
  • .pps
  • .dat
  • .ods
  • .qba
  • .qbw

It renames encrypted files using the following names:

  • {original file name and extension}.crypt

It deletes the initially executed copy of itself

NOTES:

This malware displays images of ransom note with victim ID after its encryption routine:

The ransom note text file contains the following:

  SOLUTION

Minimum Scan Engine: 9.800

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\Run
    • UpdSysDrvX32z32 = "%Application Data%\UpdSysDrv32Xz32\{8 random letters}.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows
    • UpdSysDrvNamxz32 = "{dropped copy's file name}"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows
    • UpdSysDrvz23 = "{initial malware path}"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows
    • TRUECRT32 = "TrueBOSS"

Step 5

Reset your Desktop properties

[ Learn More ]

Step 6

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %Application Data%\UpdSysDrv32Xz32

Step 7

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.
  • %System Root%\HELP_DECRYPT.jpg
  • %System Root%\HELP_DECRYPT.txt
  • %Desktop%\HELP_DECRYPT.jpg
  • %Desktop%\HELP_DECRYPT.txt
  • %User Profile%\My Documents\HELP_DECRYPT.jpg
  • %User Profile%\My Documents\HELP_DECRYPT.txt
  • {User Music}\HELP_DECRYPT.jpg
  • {User Music}\HELP_DECRYPT.txt
  • {User Pictures}\HELP_DECRYPT.jpg
  • {User Pictures}\HELP_DECRYPT.txt
  • {User Videos}\HELP_DECRYPT.jpg
  • {User Videos}\HELP_DECRYPT.txt

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_CRYPBOSS.A. 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.


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