BKDR_ANDROM.PA


 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:

187,904 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

10 Sep 2015

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:

  • %User Temp%\Hs_

(Note: %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.)

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
FWCPMYRP = "{malware path and file name}"

It modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
AutoRestartShell = "1"

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

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Windows Script\Settings

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{00021400-0000-0000-C000-000000000046}
MenuShowDelay = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer
DesktopProcess = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\FileSystem
NtfsDisableLastAccessUpdate = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
MaxConnectionsPer1_0Server = "a"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
MaxConnectionsPerServer = "a"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Tcpip\Parameters
EnablePMTUDiscovery = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Tcpip\Parameters
EnablePMTUBHDetect = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows Script\Settings
JITDebug = "0"

It modifies the following registry entries:

HKEY_CURRENT_USER\Control Panel\Desktop
AutoEndTasks = "1"

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

HKEY_CURRENT_USER\Control Panel\Desktop
MenuShowDelay = "0"

(Note: The default value data of the said registry entry is 400.)

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\Session Manager\Memory Management\
PrefetchParameters
MaxNumSavedTraces = "8"

(Note: The default value data of the said registry entry is 8.)

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\Session Manager\Memory Management\
PrefetchParameters
RootDirPath = "Prefetch"

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

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\Session Manager\Memory Management\
PrefetchParameters
BootMaxNumSections = "ff"

(Note: The default value data of the said registry entry is ff0.)

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\Session Manager\Memory Management\
PrefetchParameters
BootTimerPeriod = "{random values}"

(Note: The default value data of the said registry entry is {random values}.)

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\Session Manager\Memory Management\
PrefetchParameters
VideoInitTime = "15b5"

(Note: The default value data of the said registry entry is 3e.)

HKEY_CURRENT_USER\Control Panel\Desktop
HungAppTimeout = "1000"

(Note: The default value data of the said registry entry is 5000.)

HKEY_CURRENT_USER\Control Panel\Desktop
WaitToKillAppTimeout = "1000"

(Note: The default value data of the said registry entry is 20000.)

HKEY_CURRENT_USER\Control Panel\Desktop
UserPreferencesMask = "{random values}"

(Note: The default value data of the said registry entry is {random values}.)

HKEY_CURRENT_USER\Control Panel\Desktop
DragFullWindows = "0"

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

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\Session Manager\Memory Management\
PrefetchParameters
EnablePrefetcher = "3"

(Note: The default value data of the said registry entry is 3.)

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\Session Manager\Memory Management\
PrefetchParameters
MaxNumActiveTraces = "8"

(Note: The default value data of the said registry entry is 8.)

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Start Page = "www.naver.com"

(Note: The default value data of the said registry entry is http://www.microsoft.com/isapi/redir.dll?prd=ie&pver=6&ar=msnhome.)

Dropping Routine

This backdoor drops the following files:

  • %User Temp%\58b8052567ade6540adf05ec8d813970.zip

(Note: %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.)

Other Details

This backdoor connects to the following possibly malicious URL:

  • http://{BLOCKED}.210.248/Count.asp?ver=001&mac=00-50-56-9F-1B-AB
  • {BLOCKED}0.1
  • {BLOCKED}.110.81
  • {BLOCKED}.237.176

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.750

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

Identify and delete files detected as BKDR_ANDROM.PA using either the Startup Disk or Recovery Console

[ Learn More ]

Step 3

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\Microsoft\Windows Script
    • Settings

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • FWCPMYRP = "{malware path and file name}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{00021400-0000-0000-C000-000000000046}
    • MenuShowDelay = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer
    • DesktopProcess = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\FileSystem
    • NtfsDisableLastAccessUpdate = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • MaxConnectionsPer1_0Server = "a"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • MaxConnectionsPerServer = "a"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Tcpip\Parameters
    • EnablePMTUDiscovery = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Tcpip\Parameters
    • EnablePMTUBHDetect = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows Script\Settings
    • JITDebug = "0"

Step 5

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: AutoEndTasks = "1"
      To: AutoEndTasks = ""0""
  • In HKEY_CURRENT_USER\Control Panel\Desktop
    • From: MenuShowDelay = "0"
      To: MenuShowDelay = ""400""
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Session Manager\Memory Management\PrefetchParameters
    • From: MaxNumSavedTraces = "8"
      To: MaxNumSavedTraces = ""8""
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Session Manager\Memory Management\PrefetchParameters
    • From: RootDirPath = "Prefetch"
      To: RootDirPath = ""Prefetch""
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Session Manager\Memory Management\PrefetchParameters
    • From: BootMaxNumSections = "ff"
      To: BootMaxNumSections = ""ff0""
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Session Manager\Memory Management\PrefetchParameters
    • From: BootTimerPeriod = "{random values}"
      To: BootTimerPeriod = ""{random values}""
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Session Manager\Memory Management\PrefetchParameters
    • From: VideoInitTime = "15b5"
      To: VideoInitTime = ""3e""
  • In HKEY_CURRENT_USER\Control Panel\Desktop
    • From: HungAppTimeout = "1000"
      To: HungAppTimeout = ""5000""
  • In HKEY_CURRENT_USER\Control Panel\Desktop
    • From: WaitToKillAppTimeout = "1000"
      To: WaitToKillAppTimeout = ""20000""
  • In HKEY_CURRENT_USER\Control Panel\Desktop
    • From: UserPreferencesMask = "{random values}"
      To: UserPreferencesMask = ""{random values}""
  • In HKEY_CURRENT_USER\Control Panel\Desktop
    • From: DragFullWindows = "0"
      To: DragFullWindows = ""1""
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Session Manager\Memory Management\PrefetchParameters
    • From: EnablePrefetcher = "3"
      To: EnablePrefetcher = ""3""
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Session Manager\Memory Management\PrefetchParameters
    • From: MaxNumActiveTraces = "8"
      To: MaxNumActiveTraces = ""8""
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • From: Start Page = "www.naver.com"
      To: Start Page = ""http://www.microsoft.com/isapi/redir.dll?prd=ie&pver=6&ar=msnhome""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: AutoRestartShell = "1"
      To: AutoRestartShell = ""1""

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.
  • %User Temp%\58b8052567ade6540adf05ec8d813970.zip

Step 7

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 Temp%\Hs_

Step 8

Scan your computer with your Trend Micro product to delete files detected as BKDR_ANDROM.PA. 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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