BKDR_ESILE.SMAP

 Analysis by: Francis Xavier Antazo

 ALIASES:

a variant of Win32/Elsentric.C trojan (NOD32), W32/Agent.POF!tr (FORTINET)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • 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:

65,024 bytes

File Type:

DLL

Memory Resident:

No

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 drops the following files:

  • %Application Data%\Microsoft\{variable folder name}\{variable file name 1}.exe
  • %Application Data%\Microsoft\{variable folder name}\{variable file name 2}.dll

(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 creates the following folders:

  • %Application Data%\Microsoft\{variable folder name}\

(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.)

Autostart Technique

This backdoor registers its dropped component as a system service to ensure its automatic execution at every system startup. It does this by creating the following registry entries:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\SwPvc
Type = "20"

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\SwPvc
Start = "2"

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\SwPvc
ErrorControl = "1"

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\SwPvc
ImagePath = "%SystemRoot%\System32\svchost.exe -k mssvc"

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\SwPvc
DisplayName = "MS Software Shadow Provider"

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\SwPvc
ObjectName = "LocalSystem"

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\SwPvc
Description = "Manages software-based volume shadow taken by the Volume Shadow service. If this service is stopped, software based volume shadow cannot be manages. If this service is disabled, any service that explicitly depend on it will fail to start."

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\SwPvc\Parameters
ServiceMain = ESEntry

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\SwPvc\Parameters
ServiceDll = "%Application Data%\Microsoft\{variable folder name}\{variable file name 2}.dll"

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\SwPvc\Security
Security = "(hex values)"

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\SwPvc\Enum
0 = "Root\LEGACY_SWPVC\0000"

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\SwPvc\Enum
Count = "1"

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\SwPvc\Enum
NextInstance = "1"

It registers its dropped component as a system service to ensure its automatic execution at every system startup. It does this by creating the following registry keys:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\SwPvc

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\SwPvc\Parameters

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\SwPvc\Security

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\SwPvc\Enum

Other System Modifications

This backdoor adds the following registry entries:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows NT\CurrentVersion\Svchost
mssvc = "SwPvc"

Other Details

This backdoor connects to the following possibly malicious URL:

  • www.{BLOCKED}oahau.com
  • {BLOCKED}6.{BLOCKED}1.237.59

NOTES:

{variable folder name} may have the following values:

  • IMGP8_1
  • ime

{variable file name 1} may have the following values:

  • imjpmig
  • imekrmig

{variable file name 2} may have the following values

  • imekrcic
  • imejpcic

  SOLUTION

Minimum Scan Engine:

9.700

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 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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

 
  • In HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services
    • SwPvc

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_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Svchost
    • mssvc = "SwPvc"

Step 6

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%\Microsoft\{variable folder name}\{variable file name 1}.exe
  • %Application Data%\Microsoft\{variable folder name}\{variable file name 1}.dll

Step 7

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