Analysis by: Cris Nowell Pantanilla

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It executes the files it drops, prompting the affected system to exhibit the malicious routines they contain.

It modifies the affected system's HOSTS files. This prevents users from accessing certain websites.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size: 2,045,440 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 31 Oct 2011

Arrival Details

This Trojan 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 Trojan drops the following copies of itself into the affected system:

  • %System%\Cloud AV 2012v121.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

It terminates the execution of the copy it initially executed and executes the copy it drops instead.

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{random characters} = "%System%\Cloud AV 2012v121.exe"

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\dwme.exe
  • %Application Data%\dwme.exe
  • %Desktop%\Cloud AV 2012.lnk
  • %Application Data%\ahst.lni
  • %Start Menu%\Programs\Cloud AV 2012\Cloud AV 2012.lnk
  • %Application Data%\{random characters}\Cloud AV 2012.ico

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.. %Desktop% is the current user's desktop, which is usually C:\Documents and Settings\{User Name}\Desktop on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\Desktop on Windows Vista and 7.. %Start Menu% is the current user's Start Menu folder, which is usually C:\Windows\Start Menu or C:\Documents and Settings\{User name}\Start Menu on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu on Windows Vista and 7.)

It executes the files it drops, prompting the affected system to exhibit the malicious routines they contain.

HOSTS File Modification

This Trojan adds the following strings to the Windows HOSTS file:

  • {BLOCKED}.{BLOCKED}.179.84 craigslist.org
  • {BLOCKED}.{BLOCKED}.179.110 comcast.net
  • {BLOCKED}.{BLOCKED}.179.84 facebook.com
  • {BLOCKED}.{BLOCKED}.179.84 myspace.com
  • {BLOCKED}.{BLOCKED}.179.84 Monster.com
  • {BLOCKED}.{BLOCKED}.179.84 Expedia.com
  • {BLOCKED}.{BLOCKED}.179.84 flickr.com
  • {BLOCKED}.{BLOCKED}.179.84 amazon.com
  • {BLOCKED}.{BLOCKED}.179.84 yahoo.com
  • {BLOCKED}.{BLOCKED}.179.110 cnn.com
  • {BLOCKED}.{BLOCKED}.179.84 imdb.com
  • {BLOCKED}.{BLOCKED}.179.110 go.com
  • {BLOCKED}.{BLOCKED}.179.84 ebay.com
  • {BLOCKED}.{BLOCKED}.179.84 digg.com
  • {BLOCKED}.{BLOCKED}.122.156 wikipedia.org
  • {BLOCKED}.{BLOCKED}.122.156 youtube.com
  • {BLOCKED}.{BLOCKED}.122.156 google.com
  • {BLOCKED}.{BLOCKED}.122.156 Paypal.com

Other Details

This Trojan deletes the initially executed copy of itself

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 8.538.04
FIRST VSAPI PATTERN DATE: 31 Oct 2011
VSAPI OPR PATTERN File: 8.539.00
VSAPI OPR PATTERN Date: 01 Nov 2011

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 terminate files detected as TROJ_FAKEAV.JWE

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 3

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
    • {random characters} = "%System%\Cloud AV 2012v121.exe"

Step 4

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%\dwme.exe
  • %Application Data%\dwme.exe
  • %Desktop%\Cloud AV 2012.lnk
  • %Application Data%\ahst.lni
  • %Start Menu%\Programs\Cloud AV 2012\Cloud AV 2012.lnk
  • %Application Data%\{random characters}\Cloud AV 2012.ico

Step 5

Remove these strings added by the malware/grayware/spyware in the HOSTS file

[ Learn More ]

    • {BLOCKED}.{BLOCKED}.179.84 craigslist.org
    • {BLOCKED}.{BLOCKED}.179.110 comcast.net
    • {BLOCKED}.{BLOCKED}.179.84 facebook.com
    • {BLOCKED}.{BLOCKED}.179.84 myspace.com
    • {BLOCKED}.{BLOCKED}.179.84 Monster.com
    • {BLOCKED}.{BLOCKED}.179.84 Expedia.com
    • {BLOCKED}.{BLOCKED}.179.84 flickr.com
    • {BLOCKED}.{BLOCKED}.179.84 amazon.com
    • {BLOCKED}.{BLOCKED}.179.84 yahoo.com
    • {BLOCKED}.{BLOCKED}.179.110 cnn.com
    • {BLOCKED}.{BLOCKED}.179.84 imdb.com
    • {BLOCKED}.{BLOCKED}.179.110 go.com
    • {BLOCKED}.{BLOCKED}.179.84 ebay.com
    • {BLOCKED}.{BLOCKED}.179.84 digg.com
    • {BLOCKED}.{BLOCKED}.122.156 wikipedia.org
    • {BLOCKED}.{BLOCKED}.122.156 youtube.com
    • {BLOCKED}.{BLOCKED}.122.156 google.com
    • {BLOCKED}.{BLOCKED}.122.156 Paypal.com
"

Step 6

Scan your computer with your Trend Micro product to delete files detected as TROJ_FAKEAV.JWE. 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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