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RANSOM_CRYPSHED.I

November 01, 2015
 ALIASES:

Trojan.Cryptolocker.E (Symantec); Win32.Trojan.Crypt.Llgs (Tencent); TR/Crypt.Xpack.282375 (Avira); Crypt4.CMOT (AVG)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware

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.

  TECHNICAL DETAILS

File Size:

495,616 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

16 Oct 2015

Payload:

Encrypts files, Connects to URLs/IPs

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:

  • %All Users%\Application Data\Windows\csrss.exe

It drops the following files:

  • %System Root%\README1.txt
  • %System Root%\README2.txt
  • %System Root%\README3.txt
  • %System Root%\README4.txt
  • %System Root%\README5.txt
  • %System Root%\README6.txt
  • %System Root%\README7.txt
  • %System Root%\README8.txt
  • %System Root%\README9.txt
  • %System Root%\README10.txt
  • %Desktop%\README1.txt
  • %Desktop%\README2.txt
  • %Desktop%\README3.txt
  • %Desktop%\README4.txt
  • %Desktop%\README5.txt
  • %Desktop%\README6.txt
  • %Desktop%\README7.txt
  • %Desktop%\README8.txt
  • %Desktop%\README9.txt
  • %Desktop%\README10.txt
  • %Application Data%\{random characters}.bmp

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %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.. %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
Client Server Runtime Subsystem = "%All Users Profile%\Windows\csrss.exe"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration

HKEY_CURRENT_USER\SOFTWARE\System32\
Configuration

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
{random 2 letters} = {PUBLIC KEY}

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
cnt = 0

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
mode = 273

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
state = 3

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
state = 4

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
i = {random characters}

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
Version = 7.2.0.3

HKEY_CURRENT_USER\SOFTWARE\System32\
Configuration
{random 2 letters} = {PUBLIC KEY}

HKEY_CURRENT_USER\SOFTWARE\System32\
Configuration
cnt = 0

HKEY_CURRENT_USER\SOFTWARE\System32\
Configuration
mode = 273

HKEY_CURRENT_USER\SOFTWARE\System32\
Configuration
state = 3

HKEY_CURRENT_USER\SOFTWARE\System32\
Configuration
state = 4

HKEY_CURRENT_USER\SOFTWARE\System32\
Configuration
i = {random characters}

HKEY_CURRENT_USER\SOFTWARE\System32\
Configuration
Version = 7.2.0.3

It modifies the following registry entries:

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = "%Application Data%\{random characters}.bmp"

(Note: The default value data of the said registry entry is "{user-defined}".)

Other Details

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

  • http://myip.ru/
  • http://whoer.net/

It connects to the following possibly malicious URL:

  • http://{BLOCKED}4.ga/{path}
    where {path} can be any of the following:
    • reg.php
    • prog.php
    • err.php
    • cmd.php
    • sys.php

It renames encrypted files using the following names:

  • {random characters}.breaking_bad
  • {random characters}.heisenberg

  SOLUTION

Minimum Scan Engine:

9.750

FIRST VSAPI PATTERN FILE:

12.116.04

FIRST VSAPI PATTERN DATE:

28 Oct 2015

VSAPI OPR PATTERN File:

12.117.00

VSAPI OPR PATTERN Date:

29 Oct 2015

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

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
    • Client Server Runtime Subsystem = "%All Users Profile%\Windows\csrss.exe"

Step 5

Delete this registry key

[ 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\System32
    • Configuration
  • In HKEY_LOCAL_MACHINE\SOFTWARE\System32
    • Configuration

Step 6

Search and delete this file

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %System Root%\README1.txt
  • %System Root%\README2.txt
  • %System Root%\README3.txt
  • %System Root%\README4.txt
  • %System Root%\README5.txt
  • %System Root%\README6.txt
  • %System Root%\README7.txt
  • %System Root%\README8.txt
  • %System Root%\README9.txt
  • %System Root%\README10.txt
  • %Desktop%\README1.txt
  • %Desktop%\README2.txt
  • %Desktop%\README3.txt
  • %Desktop%\README4.txt
  • %Desktop%\README5.txt
  • %Desktop%\README6.txt
  • %Desktop%\README7.txt
  • %Desktop%\README8.txt
  • %Desktop%\README9.txt
  • %Desktop%\README10.txt
  • %Application Data%\{random characters}.bmp

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_CRYPSHED.I. 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 8

Reset your Desktop properties

[ Learn More ]

NOTES:

Restore files from backup.


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