Analysis by: Francis Xavier Antazo
ALIASES:

Ransom:Win32/Pagongcrypt.A (Microsoft); MSIL/Filecoder.TrueCrypter.A (ESET); Trojan-Ransom.MSIL.Trucry.a (Kaspersky);

 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: 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

File Size: 540,160 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 25 Apr 2016
Payload: Encrypts files, Displays message/message boxes

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 files:

  • %Application Data%\Microsoft\TrueCrypter\TrueCrypter.xml

(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 copies of itself into the affected system:

  • %Application Data%\Microsoft\TrueCrypter\TrueCrypter.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 creates the following folders:

  • %Application Data%\Microsoft\TrueCrypter\

(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.)

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
TrueCrypter = "%Application Data%\Microsoft\TrueCrypter\TrueCrypter.exe"

Process Termination

This Trojan terminates the following processes if found running in the affected system's memory:

  • antilogger
  • wireshark
  • charles
  • fiddler
  • netmon
  • reflector
  • sbiectrl
  • taskmgr

Other Details

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

  • {BLOCKED}orastral.com/innocentuser001

It encrypts files with the following extensions:

  • .7z
  • .7zip
  • .arw
  • .as
  • .asm
  • .asp
  • .aspx
  • .au3
  • .avi
  • .bash
  • .bat
  • .bmp
  • .bookmarks
  • .bsh
  • .c
  • .cbr
  • .cc
  • .cer
  • .cfm
  • .class
  • .cmd
  • .config
  • .cpp
  • .cr2
  • .crw
  • .cs
  • .csh
  • .csproj
  • .csr
  • .css
  • .csv
  • .cxx
  • .d
  • .db
  • .dcr
  • .dds
  • .deb
  • .dib
  • .dng
  • .doc
  • .docm
  • .docx
  • .dot
  • .dotm
  • .dotx
  • .dtd
  • .eps
  • .fla
  • .fpx
  • .gif
  • .gz
  • .gzip
  • .h
  • .hpp
  • .hta
  • .htm
  • .html
  • .hxx
  • .ico
  • .inc
  • .index
  • .ini
  • .jad
  • .java
  • .jfif
  • .jpe
  • .jpeg
  • .jpg
  • .js
  • .jsm
  • .json
  • .jsp
  • .jss
  • .jsx
  • .kix
  • .lex
  • .litcofee
  • .lpr
  • .lua
  • .m
  • .mov
  • .mp3
  • .mp4
  • .mrw
  • .msg
  • .mx
  • .nef
  • .ods
  • .odt
  • .org
  • .p
  • .pages
  • .pas
  • .pcd
  • .pdf
  • .pdn
  • .php
  • .php3
  • .php4
  • .php5
  • .phps
  • .phpt
  • .phtml
  • .pkg
  • .pl
  • .pm
  • .pmx
  • .png
  • .pot
  • .potm
  • .potx
  • .pp
  • .ppam
  • .ppsm
  • .ppsx
  • .pptm
  • .pptx
  • .prproj
  • .ps
  • .ps1
  • .psd
  • .psm1
  • .ptx
  • .pwi
  • .py
  • .pyc
  • .pyw
  • .r
  • .raf
  • .rar
  • .raw
  • .rb
  • .rbw
  • .rc
  • .reg
  • .resx
  • .rpm
  • .rss
  • .rtf
  • .rw2
  • .s
  • .scpt
  • .sh
  • .shtml
  • .sitx
  • .sldm
  • .sldx
  • .sln
  • .splus
  • .sql
  • .sqlite
  • .sqlite3
  • .src
  • .swift
  • .sxc
  • .tar
  • .tga
  • .thmx
  • .tif
  • .tiff
  • .ts
  • .tsv
  • .tsx
  • .txt
  • .vb
  • .vbs
  • .vcxproj
  • .veg
  • .wmw
  • .wpd
  • .wps
  • .xcodeproj
  • .xht
  • .xhtm
  • .xhtml
  • .xls
  • .xlsx
  • .xml
  • .zip
  • .zipx
  • pps
  • ppt
  • xlam
  • xlsb
  • xlsm
  • xltm
  • xltx

It renames encrypted files using the following names:

  • {original filepath}\{original filename}.{original file extention).enc

It does the following:

  • It executes the following command to delete shadow copies:
    vssadmin delete shadows /all /quiet

NOTES:

This malware displays the following after encrypting the files:

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 12.490.09
FIRST VSAPI PATTERN DATE: 26 Apr 2016
VSAPI OPR PATTERN File: 12.491.00
VSAPI OPR PATTERN Date: 27 Apr 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

[ Learn More ]

Step 4

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%\Microsoft\TrueCrypter\

Step 5

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
    • TrueCrypter = "%Application Data%\Microsoft\TrueCrypter\TrueCrypter.exe"

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_CRYPCORE.C. 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 7

Restore encrypted files from backup.


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