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TROJ_CARBERP.YWP

June 07, 2017
 Analysis by: Cris Nowell Pantanilla
 ALIASES:

Trojan-Downloader.Win32.Carberp.dp (Kaspersky); VirTool:Win32/Obfuscator (Microsoft);

 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 deletes registry entries, causing some applications and programs to not function properly.

It connects to certain websites to send and receive information. However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

109,568 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

30 May 2017

Payload:

Terminates processes

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:

  • %User Startup%\BC5MuFXZmXcUNoqV8k1uyw.exe

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Documents and Settings\{user}\Start Menu\Programs\Startup on Windows 2000 and XP, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows Vista, 7, and 8.)

It drops the following component file(s):

  • %Application Data%\Roaming\{random characters}\{random}.dat
  • %Application Data%\Roaming\{random characters}\{random}.xsi
  • %Application Data%\Roaming\{random characters}\{random}.ksi

(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 adds the following processes:

  • svchost.exe

It injects codes into the following process(es):

  • explorer.exe
  • svchost.exe

Other System Modifications

This Trojan adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Notifications\
Settings
NOC_GLOBAL_SETTING_TOASTS_ENABLED = 0

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Notifications\
Settings
NOC_GLOBAL_SETTING_ALLOW_CRITICAL_TOASTS_ABOVE_LOCK = 0

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Notifications\
Settings
NOC_GLOBAL_SETTING_ALLOW_TOASTS_ABOVE_LOCK = 0

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\PushNotifications
ToastEnabled = 0

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer
HideSCAHealth = 1

HKEY_CURRENT_USER\Software\Policies\
Microsoft\Windows\CurrentVersion\
PushNotifications
NoToastApplicationNotification = 1

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
SoftLanding
Enabled = 0

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = 2

(Note: The default value data of the said registry entry is 1.)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
SuperHidden = 1

(Note: The default value data of the said registry entry is 0.)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = 0

(Note: The default value data of the said registry entry is 1.)

It deletes the following registry entries:

HKEY_CURRENT_USER\Software\Policies\
Microsoft\Windows\System
DisableCMD =

Other Details

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

  • {BLOCKED}2fxrf4.ru

It does the following:

  • It is capable of the following:
    • Install Bootkit
    • Install FakeDLL
    • Update Plugin
    • Kill OS
    • Reboot
  • It is capable of downloading plug-in which it executes on the affected system.
  • It is capable of gathering information (system info, OS, banking information) from the affected system.
  • It checks if cpuinfo matches the following strings that are normally used by virtual machines:
    • Intel(R) Xeon(R) CPU
    • Common KVM processor
    • Common 32-bit KVM
    • Virtual CPU
    • Intel Celeron_4x0 (Conroe/Merom Class Core 2)
    • Westmere E56xx/L56xx/X56xx (Nehalem-C)
    • Intel Core 2 Duo P9xxx (Penryn Class Core 2)
    • Intel Core i7 9xx (Nehalem Class Core i7)
    • Intel Xeon E312xx (Sandy Bridge)
    • AMD Opteron 240 (Gen 1 Class Opteron)
    • AMD Opteron 22xx (Gen 2 Class Opteron)
    • AMD Opteron 23xx (Gen 3 Class Opteron)
    • AMD Opteron 62xx class CPU
    • Intel CPU version
  • It checks if being run in the following virtual machine:
    • VMwareVMware
    • XenVMMXenVMM
    • KVMKVMKVM
    • prl hyperv
    • Microsoft Hv
  • It checks the following cpu brands and if the number of cpu in the machine is 1, it terminates itself:
    • Intel(R) Core(TM) i7
    • Intel(R) Core(TM) i5
    • Intel(R) Core(TM) i3
    • Intel(R) Core(TM)2 Duo CPU
  • It checks for the presence of the following files:
    • \SystemRoot\zhsw8lZB.txt
    • \SystemRoot\VZT6nsdX.txt

However, as of this writing, the said sites are inaccessible.

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

13.438.06

FIRST VSAPI PATTERN DATE:

30 May 2017

VSAPI OPR PATTERN File:

13.439.00

VSAPI OPR PATTERN Date:

31 May 2017

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\Notifications\Settings
    • NOC_GLOBAL_SETTING_TOASTS_ENABLED = 0
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Notifications\Settings
    • NOC_GLOBAL_SETTING_ALLOW_CRITICAL_TOASTS_ABOVE_LOCK = 0
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Notifications\Settings
    • NOC_GLOBAL_SETTING_ALLOW_TOASTS_ABOVE_LOCK = 0
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\PushNotifications
    • ToastEnabled = 0
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
    • HideSCAHealth = 1
  • In HKEY_CURRENT_USER\Software\Policies\Microsoft\Windows\CurrentVersion\PushNotifications
    • NoToastApplicationNotification = 1
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\SoftLanding
    • Enabled = 0

Step 5

Restore this modified 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\Explorer\Advanced
    • From: Hidden = 2
      To: Hidden = 1
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: SuperHidden = 1
      To: SuperHidden = 0
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: ShowSuperHidden = 0
      To: ShowSuperHidden = 1

Step 6

Restore these deleted registry keys/values from backup

*Note: Only Microsoft-related keys/values will be restored. If the malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

  • In HKEY_CURRENT_USER\Software\Policies\Microsoft\Windows\System
    • DisableCMD = {user settings}

Step 7

Search and delete these files

[ 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.
%Application Data%\Roaming\{random characters}\{random}.dat
%Application Data%\Roaming\{random characters}\{random}.xsi
%Application Data%\Roaming\{random characters}\{random}.ksi

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_CARBERP.YWP. 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.


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