Analysis by: Jaime Benigno Reyes
 Modified by: Rika Joi Gregorio

ALIASES:

VirTool:Win32/CeeInject.gen!KK (Microsoft), Backdoor.Win32.Symmi.qhz (Kaspersky), Downloader-FYH!7B697E2C0B8C (McAfee)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • 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: 106,344 bytes
File Type: , EXE
Memory Resident: Yes
Initial Samples Received Date: 24 Apr 2014

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 and executes the following files:

  • %AppDataLocal%\vinitru.dll

(Note: %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local on Windows Vista and 7.)

Autostart Technique

This backdoor creates the following registry entries to enable automatic execution of dropped component at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
vinitru = "rundll32 "%AppDataLocal%\vinitru.dll",vinitru"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsfot\
Windows NT\CurrentVersion\Winlogon\
Notify\vinitru
DllName = "%AppDataLocal%\vinitru.dll"

Other System Modifications

This backdoor adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsfot\
Windows NT\CurrentVersion\Winlogon\
Notify\vinitru

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsfot\
Windows NT\CurrentVersion\Winlogon\
Notify\vinitru
Impersonate = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsfot\
Windows NT\CurrentVersion\Winlogon\
Notify\vinitru
Asynchronous = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsfot\
Windows NT\CurrentVersion\Winlogon\
Notify\vinitru
MaxWait = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsfot\
Windows NT\CurrentVersion\Winlogon\
Notify\vinitru
aamscheck = "{hex value}"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsfot\
Windows NT\CurrentVersion\Winlogon\
Notify\vinitru
Startup = "vinitru"

It creates the following registry entry(ies) to bypass Windows Firewall:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
{malware path and file name} = "{malware path and file name}:*:Enabled:GeoTrans"

Other Details

This backdoor connects to the following possibly malicious URL:

  • {BLOCKED}1.{BLOCKED}lo75.net
  • {BLOCKED}0.{BLOCKED}lo75.net
  • {BLOCKED}a.{BLOCKED}o75.net

  SOLUTION

Minimum Scan Engine: 9.700
FIRST VSAPI PATTERN FILE: 10.746.01
FIRST VSAPI PATTERN DATE: 24 Apr 2014
VSAPI OPR PATTERN File: 10.747.00
VSAPI OPR PATTERN Date: 24 Apr 2014

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

Scan your computer with your Trend Micro product and note files detected as BKDR_SYMMI.NAD

Step 3

Terminate a process file/s detected as BKDR_SYMMI.NAD

[ Learn More ]

*Note: If the detected file/s is/are not displayed in theWindows Task Manager, continue doing the next steps.

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_LOCAL_MACHINE\SOFTWARE\Microsfot\Windows NT\CurrentVersion\Winlogon\Notify
    • vinitru

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
    • vinitru = "rundll32 "%AppDataLocal%\vinitru.dll",vinitru"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • {malware path}\{malware name} = "{malware path and file name}:*:Enabled:GeoTrans"

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.
  • %AppDataLocal%\vinitru.dll

Step 7

Scan your computer with your Trend Micro product to delete files detected as BKDR_SYMMI.NAD. 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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