RANSOM_KOSTYA.A
Ransom.K0stya (Malwarebytes); Trojan.Ransom.Kostya.B (F-Secure);
Windows
Threat Type: Trojan
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
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 connects to certain websites to send and receive information.
TECHNICAL DETAILS
6,779,008 bytes
EXE
Yes
10 Oct 2016
Connects to URLs/IPs, Displays message/message boxes, Encrypts 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.
Installation
This Trojan drops the following non-malicious files:
- %User Temp%\svhost.exe
(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.)
Autostart Technique
This Trojan adds the following registry entries to enable its automatic execution at every system startup:
HKCU\Software\Microsoft\
Windows\CurrentVersion\Run
oGH = {malware path}\{malware name}.exe
Other System Modifications
This Trojan modifies the following file(s):
- It encrypts files and appends the extension .k0stya
Other Details
This Trojan connects to the following website to send and receive information:
- http://{BLOCKED}y.{BLOCKED}f.cz/kst/connect.php?id={intallation ID}&info=%7CSTART~USER:%20{computer name}~MACHINE:%20{machine name}~KEY:%{key in characters}~END%7C
It encrypts files with the following extensions:
- .3dm
- .3g2
- .3gp
- .aaf
- .accdb
- .aep
- .aepx
- .aet
- .ai
- .aif
- .arw
- .as
- .as3
- .asf
- .asp
- .asx
- .bak
- .bay
- .bmp
- .cache
- .cad
- .cdr
- .cer
- .cert
- .class
- .config
- .cpp
- .cr2
- .crt
- .crw
- .cs
- .csproj
- .css
- .csv
- .db
- .dbf
- .dcr
- .der
- .dll
- .dng
- .doc
- .docb
- .docm
- .docx
- .dot
- .dotm
- .dotx
- .dwg
- .dxf
- .dxg
- .efx
- .eps
- .erf
- .fla
- .html.xll
- .ico
- .idml
- .iff
- .indb
- .indd
- .indl
- .indt
- .inx
- .jar
- .java
- .jpeg
- .jpg
- .js
- .json
- .kdc
- .m3u
- .m3u8
- .m4u
- .max
- .mdb
- .mdf
- .mef
- .mid
- .mp3
- .mpa
- .mpg
- .mpp
- .mrw
- .msg
- .nef
- .nrw
- .odb
- .odc
- .odm
- .odp
- .ods
- .odt
- .orf
- .p12
- .p7b
- .p7c
- .pdb
- .pef
- .pem
- .pfx
- .php
- .plb
- .pmd
- .png
- .pot
- .potm
- .potx
- .ppam
- .ppj
- .pps
- .ppsm
- .ppsx
- .ppt
- .pptm
- .pptx
- .prel
- .proj
- .prproj
- .ps
- .psd
- .pst
- .ptx
- .pub
- .r3d
- .ra
- .raf
- .raw
- .rb
- .resources
- .resx
- .rtf
- .rw2
- .rwl
- .sdf
- .sldm
- .sldx
- .sln
- .sql
- .sr2
- .srf
- .srw
- .suo
- .svg
- .swf
- .tar
- .tif
- .torrent
- .txt
- .vb
- .vbproj
- .vcf
- .veg
- .vob
- .wb2
- .wma
- .wmv
- .wpd
- .wps
- .x3f
- .xaml
- .xla
- .xlam
- .xlk
- .xlm
- .xls
- .xlsb
- .xlsm
- .xlsx
- .xlt
- .xltm
- .xltx
- .xlw
- .xml
- .xqx
NOTES:
This ransomware targets the files in the following folder:
It also locks the screen and displays a ransom note in Czech language:
It warns that files are encrypted and the user needs to pay CZK 300. If not paid within 12 hours, the ransom increases to CZK 2000; and if after 24 hours the ransom is still not paid, encrypted files will be deleted.
SOLUTION
9.800
12.828.03
10 Oct 2016
12.829.00
10 Oct 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
- oGH = {malware path}\{malware name}.exe
- oGH = {malware path}\{malware name}.exe
Step 5
Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_KOSTYA.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.
Step 6
Restore encrypted files from backup.
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