Modified by: Erika Bianca Mendoza
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This backdoor may be unknowingly downloaded by a user while visiting malicious websites.

It also has rootkit capabilities, which enables it to hide its processes and files from the user.

  TECHNICAL DETAILS

File Size: Varies
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 28 Oct 2011

Arrival Details

This backdoor may be unknowingly downloaded by a user while visiting malicious websites.

Installation

This backdoor drops the following files:

  • %Application Data%\{random}\@
  • %Application Data%\{random}\X
  • %Windows%\{random numbers}

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.. %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

It creates the following folders:

  • %Application Data%\{random}
  • %Application Data%\{random}\U

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "%Application Data%\{random}\X"

It registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random}
Type = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random}
Start = "3"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random}
ImagePath = "\systemroot\1493438348:1945172902.exe"

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CURRENT_USER\Software\{random}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{b1041c7f-46ea-d87c-4a51-abba7b80f3da}

It adds the following registry entries:

HKEY_CURRENT_USER\Software\{random}
u = "{dword value}"

HKEY_CURRENT_USER\Software\{random}
id = "{hex values}"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{b1041c7f-46ea-d87c-4a51-abba7b80f3da}
u = "{dword value}"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{b1041c7f-46ea-d87c-4a51-abba7b80f3da}
cid = "{hex values}"

Rootkit Capabilities

This backdoor also has rootkit capabilities, which enables it to hide its processes and files from the user.

Other Details

This backdoor connects to the following possibly malicious URL:

  • http://{BLOCKED}hu.cn/stat2.php?w={value}&i={value}&a={value}
  • http://{BLOCKED}hu.cn/bad.php?w={value}&fail={value}&i={value}

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 8.530.02
FIRST VSAPI PATTERN DATE: 28 Oct 2011

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Identify and delete files detected as BKDR_ZACESS.SMAE using the Recovery Console

[ Learn More ]

Step 3

To delete the random service key this malware/grayware created:

  1. Scan your computer with your Trend Micro product and take note of the name of the malware/grayware/spyware detected.
  2. Open Registry Editor. To do this, click Start>Run, type regedit in the text box provided, then press Enter.
  3. Press CTRL+F.
  4. In the Find dialog box, type the file name of the malware detected earlier.
    (Note: Make sure that only the data checkbox is selected, then click Find Next.)

    5. find.

  5. Once found, in the right panel, check if the result is the following value-data pair:
    ImagePath = {malware/grayware path and file name}
  6. If yes, in the left panel, locate the service where the data is under.
  7. Right-click on the located service in the left panel and choose Delete.
  8. Repeat steps 2 to 6 until the Finished searching through the registry dialog box appears.
  9. Close Registry Editor.

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\SOFTWARE\Classes\Interface\
    • {b1041c7f-46ea-d87c-4a51-abba7b80f3da}

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 NT\CurrentVersion\Winlogon
    • Shell = %Application Data%\{random}\X

Step 6

Search and delete these files

[ Learn More ]
There may be some component 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%\{random}\@
  • %Application Data%\{random}\X
  • %Windows%\{random numbers}

Step 7

Search and delete these folders

[ 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.
  • %Application Data%\{random}
  • %Application Data%\{random}\U

Step 8

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