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Ransom_CERBER.YYZ

August 05, 2016
 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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 disables Task Manager, Registry Editor, and Folder Options.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

799,018 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

05 Aug 2016

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:

  • %User Profile%\{7CF6D5B2-7F46-D112-55F6-A978382F9CF0}\osuninst.exe

(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.)

It creates the following folders:

  • %User Profile%\Application Data\{7CF6D5B2-7F46-D112-55F6-A978382F9CF0}

(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.)

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
osuninst = "%User Profile%\{7CF6D5B2-7F46-D112-55F6-A978382F9CF0}\osuninst.exe "

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\RunOnce
osuninst = "%User Profile%\{7CF6D5B2-7F46-D112-55F6-A978382F9CF0}\osuninst.exe "

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Printers\Defaults\
{3C750734-366C-AAE6-17A8-9BF7C15DD707}

HKEY_USERS\S-1-5-21-1645522239-1292428093-682003330-1003\Software\
Microsoft\Windows\CurrentVersion\
RunOnce

It adds the following registry entries:

HKEY_CURRENT_USER\Printers\Defaults\
{3C750734-366C-AAE6-17A8-9BF7C15DD707}
Component_01 = "{random values}"

HKEY_CURRENT_USER\Printers\Defaults\
{3C750734-366C-AAE6-17A8-9BF7C15DD707}
Component_00 = "{random values}"

HKEY_CURRENT_USER\Software\Microsoft\
Command Processor
AutoRun = "%User Profile%\{7CF6D5B2-7F46-D112-55F6-A978382F9CF0}\osuninst.exe "

HKEY_CURRENT_USER\Printers\Defaults\
{3C750734-366C-AAE6-17A8-9BF7C15DD707}
Installed = "1"

It modifies the following registry entries:

HKEY_CURRENT_USER\Control Panel\Desktop
SCRNSAVE.EXE = "%User Profile%\{7CF6D5B2-7F46-D112-55F6-A978382F9CF0}\osuninst.exe "

(Note: The default value data of the said registry entry is %Windows%\system32\logon.scr.)

It creates the following registry entry(ies) to disable Task Manager, Registry Tools and Folder Options:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer
Run = "%User Profile%\{7CF6D5B2-7F46-D112-55F6-A978382F9CF0}\osuninst.exe "

Dropping Routine

This Trojan drops the following files:

  • %User Startup%\osuninst.lnk
  • %User Profile%\# DECRYPT MY FILES #.html
  • %User Profile%\# DECRYPT MY FILES #.txt
  • %User Profile%\# DECRYPT MY FILES #.url
  • %User Profile%\# DECRYPT MY FILES #.vbs
  • %Temporary Internet Files%\Content.IE5\ZSGKJKO6\# DECRYPT MY FILES #.html
  • %Temporary Internet Files%\Content.IE5\ZSGKJKO6\# DECRYPT MY FILES #.txt
  • %Temporary Internet Files%\Content.IE5\ZSGKJKO6\# DECRYPT MY FILES #.url
  • %Temporary Internet Files%\Content.IE5\09RWHJQN\# DECRYPT MY FILES #.html
  • %Temporary Internet Files%\Content.IE5\ZSGKJKO6\# DECRYPT MY FILES #.vbs
  • %Temporary Internet Files%\Content.IE5\09RWHJQN\# DECRYPT MY FILES #.txt
  • %Temporary Internet Files%\Content.IE5\09RWHJQN\# DECRYPT MY FILES #.url
  • %Temporary Internet Files%\Content.IE5\09RWHJQN\# DECRYPT MY FILES #.vbs
  • %Temporary Internet Files%\Content.IE5\BVLBNMKH\# DECRYPT MY FILES #.html
  • %Temporary Internet Files%\Content.IE5\BVLBNMKH\# DECRYPT MY FILES #.txt
  • %Temporary Internet Files%\Content.IE5\BVLBNMKH\# DECRYPT MY FILES #.url
  • %Temporary Internet Files%\Content.IE5\BVLBNMKH\# DECRYPT MY FILES #.vbs
  • %User Profile%\Cookies\# DECRYPT MY FILES #.html
  • %User Profile%\Cookies\# DECRYPT MY FILES #.txt
  • %User Profile%\Cookies\# DECRYPT MY FILES #.url
  • %User Profile%\Cookies\# DECRYPT MY FILES #.vbs
  • %Temporary Internet Files%\Content.IE5\ZDGZNKA5\# DECRYPT MY FILES #.html
  • %Temporary Internet Files%\Content.IE5\ZDGZNKA5\# DECRYPT MY FILES #.txt
  • %Temporary Internet Files%\Content.IE5\ZDGZNKA5\# DECRYPT MY FILES #.url
  • %Temporary Internet Files%\Content.IE5\ZDGZNKA5\# DECRYPT MY FILES #.vbs
  • %User Profile%\MSHist012013061320130614\# DECRYPT MY FILES #.html
  • %User Profile%\MSHist012013061320130614\# DECRYPT MY FILES #.txt
  • %User Profile%\MSHist012013061320130614\# DECRYPT MY FILES #.url
  • %User Profile%\MSHist012013061320130614\# DECRYPT MY FILES #.vbs
  • %System Root%\# DECRYPT MY FILES #.html
  • %System Root%\# DECRYPT MY FILES #.txt
  • %System Root%\# DECRYPT MY FILES #.url
  • %System Root%\# DECRYPT MY FILES #.vbs
  • %User Temp%\# DECRYPT MY FILES #.html
  • %User Temp%\# DECRYPT MY FILES #.txt
  • %Application Data%\# DECRYPT MY FILES #.html
  • %User Temp%\# DECRYPT MY FILES #.url
  • %Application Data%\# DECRYPT MY FILES #.txt
  • %Application Data%\# DECRYPT MY FILES #.url
  • %User Temp%\# DECRYPT MY FILES #.vbs
  • %Application Data%\# DECRYPT MY FILES #.vbs
  • %Application Data%\Microsoft\# DECRYPT MY FILES #.html
  • %Application Data%\Microsoft\# DECRYPT MY FILES #.txt
  • %Application Data%\Microsoft\# DECRYPT MY FILES #.url
  • %Application Data%\Microsoft\# DECRYPT MY FILES #.vbs
  • %Application Data%\Microsoft\Internet Explorer\# DECRYPT MY FILES #.html
  • %Application Data%\Microsoft\Internet Explorer\# DECRYPT MY FILES #.txt
  • %Application Data%\Microsoft\Internet Explorer\# DECRYPT MY FILES #.url
  • %Application Data%\Microsoft\Internet Explorer\# DECRYPT MY FILES #.vbs

(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.. %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.. %Temporary Internet Files% is the Temporary Internet Files folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temporary Internet Files on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Microsoft\Windows\Temporary Internet Files on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), and Windows Server 2008; C:\Users\{user name}\AppData\Local\Microsoft\Windows\INetCache on Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), and Windows Server 2012.. %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %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.. %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.)

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}o.io/json
  • {BLOCKED}54.220

It deletes itself after execution.

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.8

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

Restart in Safe Mode

[ Learn More ]

Step 3

Enable Registry Editor, Task Manager, and Folder options

[ Learn More ]
By doing this step, you also enable other applications/programs disabled by this malware/grayware/spyware.

Step 4

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\Printers\Defaults
    • {3C750734-366C-AAE6-17A8-9BF7C15DD707}
  • In HKEY_USERS\S-1-5-21-1645522239-1292428093-682003330-1003\Software\Microsoft\Windows\CurrentVersion
    • RunOnce

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
    • osuninst = "%User Profile%\{7CF6D5B2-7F46-D112-55F6-A978382F9CF0}\osuninst.exe "
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce
    • osuninst = "%User Profile%\{7CF6D5B2-7F46-D112-55F6-A978382F9CF0}\osuninst.exe "
  • In HKEY_CURRENT_USER\Printers\Defaults\{3C750734-366C-AAE6-17A8-9BF7C15DD707}
    • Component_01 = "{random values}"
  • In HKEY_CURRENT_USER\Printers\Defaults\{3C750734-366C-AAE6-17A8-9BF7C15DD707}
    • Component_00 = "{random values}"
  • In HKEY_CURRENT_USER\Software\Microsoft\Command Processor
    • AutoRun = "%User Profile%\{7CF6D5B2-7F46-D112-55F6-A978382F9CF0}\osuninst.exe "
  • In HKEY_CURRENT_USER\Printers\Defaults\{3C750734-366C-AAE6-17A8-9BF7C15DD707}
    • Installed = "1"

Step 6

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Control Panel\Desktop
    • From: SCRNSAVE.EXE = "%User Profile%\{7CF6D5B2-7F46-D112-55F6-A978382F9CF0}\osuninst.exe "
      To: SCRNSAVE.EXE = ""%Windows%\system32\logon.scr""

Step 7

Search and delete these components

[ Learn More ]
There may be some components 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.
  • %User Startup%\osuninst.lnk
  • %User Profile%\# DECRYPT MY FILES #.html
  • %User Profile%\# DECRYPT MY FILES #.txt
  • %User Profile%\# DECRYPT MY FILES #.url
  • %User Profile%\# DECRYPT MY FILES #.vbs
  • %Temporary Internet Files%\Content.IE5\ZSGKJKO6\# DECRYPT MY FILES #.html
  • %Temporary Internet Files%\Content.IE5\ZSGKJKO6\# DECRYPT MY FILES #.txt
  • %Temporary Internet Files%\Content.IE5\ZSGKJKO6\# DECRYPT MY FILES #.url
  • %Temporary Internet Files%\Content.IE5\09RWHJQN\# DECRYPT MY FILES #.html
  • %Temporary Internet Files%\Content.IE5\ZSGKJKO6\# DECRYPT MY FILES #.vbs
  • %Temporary Internet Files%\Content.IE5\09RWHJQN\# DECRYPT MY FILES #.txt
  • %Temporary Internet Files%\Content.IE5\09RWHJQN\# DECRYPT MY FILES #.url
  • %Temporary Internet Files%\Content.IE5\09RWHJQN\# DECRYPT MY FILES #.vbs
  • %Temporary Internet Files%\Content.IE5\BVLBNMKH\# DECRYPT MY FILES #.html
  • %Temporary Internet Files%\Content.IE5\BVLBNMKH\# DECRYPT MY FILES #.txt
  • %Temporary Internet Files%\Content.IE5\BVLBNMKH\# DECRYPT MY FILES #.url
  • %Temporary Internet Files%\Content.IE5\BVLBNMKH\# DECRYPT MY FILES #.vbs
  • %User Profile%\Cookies\# DECRYPT MY FILES #.html
  • %User Profile%\Cookies\# DECRYPT MY FILES #.txt
  • %User Profile%\Cookies\# DECRYPT MY FILES #.url
  • %User Profile%\Cookies\# DECRYPT MY FILES #.vbs
  • %Temporary Internet Files%\Content.IE5\ZDGZNKA5\# DECRYPT MY FILES #.html
  • %Temporary Internet Files%\Content.IE5\ZDGZNKA5\# DECRYPT MY FILES #.txt
  • %Temporary Internet Files%\Content.IE5\ZDGZNKA5\# DECRYPT MY FILES #.url
  • %Temporary Internet Files%\Content.IE5\ZDGZNKA5\# DECRYPT MY FILES #.vbs
  • %User Profile%\MSHist012013061320130614\# DECRYPT MY FILES #.html
  • %User Profile%\MSHist012013061320130614\# DECRYPT MY FILES #.txt
  • %User Profile%\MSHist012013061320130614\# DECRYPT MY FILES #.url
  • %User Profile%\MSHist012013061320130614\# DECRYPT MY FILES #.vbs
  • %System Root%\# DECRYPT MY FILES #.html
  • %System Root%\# DECRYPT MY FILES #.txt
  • %System Root%\# DECRYPT MY FILES #.url
  • %System Root%\# DECRYPT MY FILES #.vbs
  • %User Temp%\# DECRYPT MY FILES #.html
  • %User Temp%\# DECRYPT MY FILES #.txt
  • %Application Data%\# DECRYPT MY FILES #.html
  • %User Temp%\# DECRYPT MY FILES #.url
  • %Application Data%\# DECRYPT MY FILES #.txt
  • %Application Data%\# DECRYPT MY FILES #.url
  • %User Temp%\# DECRYPT MY FILES #.vbs
  • %Application Data%\# DECRYPT MY FILES #.vbs
  • %Application Data%\Microsoft\# DECRYPT MY FILES #.html
  • %Application Data%\Microsoft\# DECRYPT MY FILES #.txt
  • %Application Data%\Microsoft\# DECRYPT MY FILES #.url
  • %Application Data%\Microsoft\# DECRYPT MY FILES #.vbs
  • %Application Data%\Microsoft\Internet Explorer\# DECRYPT MY FILES #.html
  • %Application Data%\Microsoft\Internet Explorer\# DECRYPT MY FILES #.txt
  • %Application Data%\Microsoft\Internet Explorer\# DECRYPT MY FILES #.url
  • %Application Data%\Microsoft\Internet Explorer\# DECRYPT MY FILES #.vbs

Step 8

Search and delete this folder

[ 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.
  • %User Profile%\Application Data\{7CF6D5B2-7F46-D112-55F6-A978382F9CF0}

Step 9

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