RANSOM_CRYPTESLA.G

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 does not have any propagation routine.

It does not have any backdoor routine.

It modifies the Internet Explorer Zone Settings.

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

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.

Installation

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

• %Application Data%\svc{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:

• %User Profile%\My Documents\Recovery_File_{random letters}.txt
• %Desktop%\RESTORE_FILES.HTML
• %Desktop%\RESTORE_FILES.TXT
• %Desktop%\RESTORE_FILES.BMP

(Note: %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.. %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.)

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{installation ID} = "%Application Data%\svc{random letters}.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{installation ID} = "%Application Data%\svc{random letters}.exe"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\msys

HKEY_CURRENT_USER\Software\{installation ID}

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
system
EnabledLinkConnections = "1"

HKEY_CURRENT_USER\Software\{installation ID}
data = "{encryption information}"

HKEY_CURRENT_USER\Software\msys
ID = "{installation ID}"

Propagation

This Trojan does not have any propagation routine.

Backdoor Routine

This Trojan does not have any backdoor routine.

Process Termination

This Trojan terminates processes or services that contain any of the following strings if found running in the affected system's memory:

• taskmgr
• procexp
• regedit
• msconfig

Web Browser Home Page and Search Page Modification

This Trojan modifies the Internet Explorer Zone Settings.

Information Theft

This Trojan gathers the following data:

• Infection status
• Encryption key
• Bitcoin address
• Total size of encrypted files
• Malware version
• OS information
• Tor2web gateway used
• Victim's IP address
• Installation/Victim ID

Other Details

This Trojan connects to the following URL(s) to get the affected system's IP address:

• ipinfo.io/ip

It connects to the following website to send and receive information:

• http://{BLOCKED}ppen.nl/{path}/{data}
• http://{BLOCKED}rnotube.org/{path}/{data}
• http://{BLOCKED}almarketing.com/{path}/{data}
• http://{BLOCKED}erheath.ru/{path}/{data}
• http://{BLOCKED}erests.com/{path}/{data}
• http://{BLOCKED}tynowbooksandgifts.com/{path}/{data}
  
  where {path} can be any of the following:
  • wp-content/themes/r.php?
  • inst.php?
  
  
  

It encrypts files with the following extensions:

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

It deletes the initially executed copy of itself

NOTES:

It appends the extension .aaa to the filename of the encrypted files.

It drops restore_files_{random letters}.html and restore_files_{random letters}.txt to the folders where the files are encrypted.

Here are the screenshots of its ransom notes showing instructions on how to restore the encrypted files by paying in Bitcoin through their onion payment sites: