RANSOM_CRYPTESLA.YUYAIH
Win32/Filecoder.TeslaCrypt.I (ESET-NOD32)
Windows
Threat Type: Trojan
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
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 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 gathers information and reports it to its servers.
TECHNICAL DETAILS
339,968 bytes
EXE
Yes
08 Mar 2016
Connects to URLs/IPs, Displays message/message boxes, Encrypts files, Steals information
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:
- %Windows%\{random filename}.exe
(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)
It adds the following mutexes to ensure that only one of its copies runs at any one time:
- ityeofm9234-23423
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
{random} = "%System%\cmd.exe /c start "" "%Windows%\{random filename}.exe""
Other System Modifications
This Trojan adds the following registry keys:
HKEY_CURRENT_USER\Software\xxxsys
HKEY_CURRENT_USER\Software\{Installation ID}
It adds the following registry entries:
HKEY_CURRENT_USER\Software\{Installation ID}
data = {encryption information}
HKEY_CURRENT_USER\Software\xxxsys
ID = {Installation ID}
Propagation
This Trojan does not have any propagation routine.
Backdoor Routine
This Trojan does not have any backdoor routine.
Web Browser Home Page and Search Page Modification
This Trojan modifies the Internet Explorer Zone Settings.
Dropping Routine
This Trojan drops the following files:
- %User Profile%\Documents\recover_file_{random letters}.txt
- %Desktop%\RECOVERY.HTM
- %Desktop%\RECOVERY.png
- %Desktop%\RECOVERY.TXT
(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.)
Other Details
This Trojan connects to the following website to send and receive information:
- http://www.{BLOCKED}la.com/imgs/videos/bsts.php
- http://{BLOCKED}de.co.kr/board/common/bsts.php
- http://{BLOCKED}anph.com/wp-content/uploads/bsts.php
- http://{BLOCKED}i.com/whiteboard_dangam/admin/bsts.php
- http://{BLOCKED}inslow.com/csys.php
- http://{BLOCKED}dress.pl/wp-content/themes/sketch/csys.php
It encrypts files with the following extensions:
- .3fr
- .7z
- .accdb
- .ai
- .amp
- .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
- .indd
- .itd
- .itdb
- .itl
- .itm
- .iwd
- .iwi
- .jpeg
- .jpg
- .js
- .kdb
- .kdc
- .kf
- .layout
- .lbf
- .litemod
- .lrf
- .ltx
- .lvl
- .m2
- .m3u
- .m4a
- .mcmeta
- .mdb
- .mdbackup
- .mdd
- .mddata
- .mdf
- .mef
- .menu
- .mlx
- .mov
- .mp4
- .mpqge
- .mrwref
- .ncf
- .nrw
- .ntl
- .odb
- .odc
- .odm
- .odp
- .ods
- .odt
- .orf
- .p12
- .p7b
- .p7c
- .pak
- .pdd
- .pef
- .pem
- .pfx
- .pkb
- .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
- .vfs
- .vfs0
- .vpk
- .vpp_pc
- .vtf
- .w3x
- .wallet
- .wb2
- .wma
- .wmo
- .wmv
- .wotreplay
- .wpd
- .wps
- .x3f
- .xf
- .xlk
- .xls
- .xlsb
- .xlsm
- .xlsx
- .xxx
- .zip
- .ztm
- .ztmp
It opens the following files:
- %Desktop%\RECOVERY.HTM
- %Desktop%\RECOVERY.png
- %Desktop%\RECOVERY.TXT
(Note: %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 gathers the following information and reports it to its servers:
- Infection status
- Bitcoin address
- Total size of encrypted files
- Malware version
- OS information
- Installation ID
NOTES:
This malware deletes shadow copies by executing the following command:
vssadmin.exe delete shadows /all /Quiet
It terminates processes containing the following strings:
- askmg
- cmd
- egedi
- rocex
- sconfi
It appends the extension .mp3 to the file name of the encrypted files. It avoids encrypting files found in the following folders:
- Windows
- Program Files
- %All Users Profile%\Application Data - if infected system is running Windows XP or older versions
- ProgramData - if infected system is running Windows Vista or newer versions
It avoids encrypting files with the following strings:
- recove
- .mp3
It drops Recovery+{random letters}.png, Recovery+{random letters}.txt, and Recovery+{random letters}.html to the folders where the files are encrypted.
It encrypts files in all fixed, removable, and network drives and shares.
SOLUTION
9.800
12.364.02
25 Feb 2016
12.365.00
26 Feb 2016
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
Step 4
Delete this registry value
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
- {random} = "%System%\cmd.exe /c start "" "%Windows%\{random filename}.exe""
- {random} = "%System%\cmd.exe /c start "" "%Windows%\{random filename}.exe""
Step 5
Delete this registry key
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
- xxxsys
- xxxsys
- In HKEY_CURRENT_USER\Software
- {Installation ID}
- {Installation ID}
Step 6
Search and delete these files
- %User Profile%\Documents\recover_file_{random letters}.txt
- %Desktop%\RECOVERY.HTM
- %Desktop%\RECOVERY.png
- %Desktop%\RECOVERY.TXT
- Recovery+{random letters}.png
- Recovery+{random letters}.txt
- Recovery+{random letters}.html
Step 7
Reset Internet security settings
Step 8
Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_CRYPTESLA.YUYAIH. 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 9
Restore encrypted files from backup.
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