BKDR_BAYROB.CXC


 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This backdoor 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:

1,554,432 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

10 Feb 2016

Arrival Details

This backdoor 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 backdoor creates the following folders:

  • %System%\yydlybphclhkh

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

Autostart Technique

This backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Protection WWAN Error Audio = "%System%\fclvyfmphdz.exe"

Other System Modifications

This backdoor adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SystemRestore
DisableConfig = "1"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
FirewallDisableNotify = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
FirewallOverride = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
AntiVirusDisableNotify = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
AntiVirusOverride = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SystemRestore
DisableSR = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SystemRestore
RPSessionInterval = "0"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SystemRestore
RPGlobalInterval = "0"

(Note: The default value data of the said registry entry is 15180.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SystemRestore
RPLifeInterval = "0"

(Note: The default value data of the said registry entry is 76a700.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SystemRestore
TimerInterval = "0"

(Note: The default value data of the said registry entry is 78.)

It deletes the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
ShellServiceObjects\{FD6905CE-952F-41F1-9A6F-135D9C6622CC}

Dropping Routine

This backdoor drops the following files:

  • %System%\yydlybphclhkh\tst
  • %User Temp%\bwsvmgmn14egmpsvrvx6lco.exe
  • %System%\yydlybphclhkh\lck
  • %User Profile%\RSA\S-1-5-18
  • %System%\yydlybphclhkh\rng
  • %System%\yydlybphclhkh\run
  • %System%\yydlybphclhkh\cfg
  • %Temp%\bwsvmgxt0bepmps.exe
  • %Temp%\bwsvmgrwqtz9mps.exe
  • %Temp%\bwsvmgb104zwmps.exe
  • %Temp%\bwsvmg4tpm6zmps.exe
  • %Temp%\bwsvmg4tpm70mps.exe
  • %Temp%\bwsvmg3l6dj2mps.exe
  • %Temp%\bwsvmgcdjky7mps.exe
  • %Temp%\bwsvmg33dizsmps.exe
  • %Temp%\bwsvmgcksqrjmps.exe
  • %Temp%\bwsvmgxkunwumps.exe
  • %Temp%\bwsvmgpstjkzmps.exe
  • %Temp%\bwsvmgve74gxmps.exe
  • %System%\fclvyfmphdz.exe
  • %System%\djawaivewnlx.exe

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 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.. %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.. %Temp% is the Windows temporary folder, where it usually is C:\Windows\Temp on all Windows operating system versions.)

Other Details

This backdoor connects to the following possibly malicious URL:

  • {BLOCKED}.124.153
  • {BLOCKED}.215.249
  • {BLOCKED}.240.171

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

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • Protection WWAN Error Audio = "%System%\fclvyfmphdz.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SystemRestore
    • DisableConfig = "1"

Step 4

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    • FirewallDisableNotify = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    • FirewallOverride = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    • AntiVirusDisableNotify = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    • AntiVirusOverride = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SystemRestore
    • DisableSR = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SystemRestore
    • RPSessionInterval = "0"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SystemRestore
    • From: RPGlobalInterval = "0"
      To: RPGlobalInterval = ""15180""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SystemRestore
    • From: RPLifeInterval = "0"
      To: RPLifeInterval = ""76a700""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SystemRestore
    • From: TimerInterval = "0"
      To: TimerInterval = ""78""

Step 5

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.
  • %System%\yydlybphclhkh\tst
  • %User Temp%\bwsvmgmn14egmpsvrvx6lco.exe
  • %System%\yydlybphclhkh\lck
  • %User Profile%\RSA\S-1-5-18
  • %System%\yydlybphclhkh\rng
  • %System%\yydlybphclhkh\run
  • %System%\yydlybphclhkh\cfg
  • %Temp%\bwsvmgxt0bepmps.exe
  • %Temp%\bwsvmgrwqtz9mps.exe
  • %Temp%\bwsvmgb104zwmps.exe
  • %Temp%\bwsvmg4tpm6zmps.exe
  • %Temp%\bwsvmg4tpm70mps.exe
  • %Temp%\bwsvmg3l6dj2mps.exe
  • %Temp%\bwsvmgcdjky7mps.exe
  • %Temp%\bwsvmg33dizsmps.exe
  • %Temp%\bwsvmgcksqrjmps.exe
  • %Temp%\bwsvmgxkunwumps.exe
  • %Temp%\bwsvmgpstjkzmps.exe
  • %Temp%\bwsvmgve74gxmps.exe
  • %System%\fclvyfmphdz.exe
  • %System%\djawaivewnlx.exe

Step 6

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.
  • %System%\yydlybphclhkh

Step 7

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

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\ShellServiceObjects
    • {FD6905CE-952F-41F1-9A6F-135D9C6622CC}


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