Analysis by: Christopher Daniel So
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This Trojan may be dropped by other malware.

However, as of this writing, the said sites are inaccessible. It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size: Varies
File Type: PE
Memory Resident: Yes
Initial Samples Received Date: 30 Jul 2011

Arrival Details

This Trojan may be dropped by the following malware:

  • TROJ_FAKEAV.SMHB

Installation

This Trojan drops the following files:

  • %System%\calcmsg.dll - also detected by Trend Micro as TROJ_FAKESYS.HBB

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

Autostart Technique

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

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\Session Manager\AppCertDlls
smsssupd = "%System%\calcmsg.dll"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\AppDataLow\
Software\Microsoft\Internet Explorer\
Security\AntiPhishing\BEF6E7E9-9034-FE03-2D86-B11AE7A80B5C

It adds the following registry entries:

HKEY_CURRENT_USER\Software\AppDataLow\
Software\Microsoft\Internet Explorer\
Security\AntiPhishing\BEF6E7E9-9034-FE03-2D86-B11AE7A80B5C
ID = {random values}

HKEY_CURRENT_USER\Software\AppDataLow\
Software\Microsoft\Internet Explorer\
Security\AntiPhishing\BEF6E7E9-9034-FE03-2D86-B11AE7A80B5C
Group = 40c

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}ationname.co.cc/config.php?{random string}
  • http://{BLOCKED}ationname.co.cc/data.php?{random string}
  • http://{BLOCKED}ationname.co.cc/task.php?{random string}
  • http://{BLOCKED}aryprote.co.cc/config.php?{random string}
  • http://{BLOCKED}aryprote.co.cc/data.php?{random string}
  • http://{BLOCKED}aryprote.co.cc/task.php?{random string}

However, as of this writing, the said sites are inaccessible.

It deletes the initially executed copy of itself

NOTES:
This malware is executed each time a new process is created.

It hooks the following Netscape Portable Runtime (NSPR4) API functions if firefox.exe is running:

  • PR_Close
  • PR_Read
  • PR_Write

It hooks the following Windows Internet (WININET) API functions if Internet Explorer is running:

  • HttpOpenRequestA
  • HttpOpenRequestW
  • HttpSendRequestA
  • HttpSendRequestW
  • InternetConnectA
  • InternetConnectW
  • InternetQueryDataAvailable
  • InternetReadFile
  • InternetReadFileExA
  • InternetReadFileExW

  SOLUTION

Minimum Scan Engine: 8.900
FIRST VSAPI PATTERN FILE: 8.318.06
FIRST VSAPI PATTERN DATE: 29 Jul 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

Remove the malware/grayware file that dropped/downloaded TROJ_FAKESYS.HBB

    TROJ_FAKEAV.SMHB

Step 3

Identify and delete files detected as TROJ_FAKESYS.HBB using either the Startup Disk or Recovery Console

[ Learn More ]

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\SYSTEM\CurrentControlSet\Control\Session Manager\AppCertDlls
    • smsssupd="%System%\calcmsg.dll"

Step 5

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\AppDataLow\Software\Microsoft\Internet Explorer\Security\AntiPhishing
    • BEF6E7E9-9034-FE03-2D86-B11AE7A80B5C

Step 6

Scan your computer with your Trend Micro product to delete files detected as TROJ_FAKESYS.HBB. 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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