RANSOM_CRYPTESLA.XXQQ

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 modifies the Internet Explorer Zone Settings.

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:

• %AppDataLocal%\{random filename}.exe

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

• %AppDataLocal%\log.html - contains the list of encrypted files
• %Desktop%\Save_Files.lnk - shortcut pointing to the dropped copy
• %Desktop%\HELP_RESTORE_FILES.bmp
• %Desktop%\HELP_RESTORE_FILES.txt
• %User Profile%\Documents\RECOVERY_FILE.txt
• %AppDataLocal%\GDIPFONTCACHEV1.DAT
• {Folders of all files encrypted}\HELP_RESTORE_FILES_{random 5 letters}.TXT

(Note: %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local 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.. %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 mutexes to ensure that only one of its copies runs at any one time:

• safsdfasdfwrtqr15

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
AVrSvc = %AppDataLocal%\{random filename}.exe

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
AVrSvc = %AppDataLocal%\{random filename}.exe

Other System Modifications

This Trojan modifies the following registry entries:

HKEY_CURRENT_USER\Control Panel\Desktop
WallpaperStyle = 0

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

HKEY_CURRENT_USER\Control Panel\Desktop
TileWallpaper = 0

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

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = %Desktop%\HELP_RESTORE_FILES.bmp

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

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

Backdoor Routine

This Trojan connects to the following URL(s) to send and receive commands from a remote malicious user:

• {BLOCKED}egu6hn.tor2web.{BLOCKED}gie.de:443
• {BLOCKED}egu6hn.{BLOCKED}s4we39.com
• {BLOCKED}egu6hn.{BLOCKED}kjc38.com
• {BLOCKED}egu6hn.{BLOCKED}b.org

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
• cmd.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 URL(s) to get the affected system's IP address:

• http://ipinfo.io/ip

It encrypts files with the following extensions:

• .3fr
• .7z
• .accdb
• .ai
• .apk
• .arch00
• .arw
• .asset
• .avi
• .bar
• .bay
• .bc6
• .bc7
• .bigwallet
• .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
• .indd
• .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
• .r3d
• .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

It renames encrypted files using the following names:

• {Original Filename}.exx

It deletes the initially executed copy of itself

NOTES:

This malware encrypts files in all fixed, removable, and network drives and shares. It deletes shadow copies by executing the following command:

• vssadmin.exe delete shadows /all /Quiet

It displays the following message box which informs the user of what happened to the user's files and how to restore them.

It drops a text file in all the folders of the files it successfully encrypts.