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TROJ_FAKEAV.BYL

April 19, 2011
 Analysis by: Karl Dominguez
 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 downloaded by other malware/grayware/spyware from remote sites. It may be unknowingly downloaded by a user while visiting malicious websites.

It connects to certain URLs. It may do this to remotely inform a malicious user of its installation. It may also do this to download possibly malicious files onto the computer, which puts the computer at a greater risk of infection by other threats.

It installs a fake antivirus/antispyware software. It poses as an antispyware application that displays deceptive warnings and misleading scan results. It may also add other applications which it detects upon its installation. It displays fake alerts that warn users of infection. It also displays fake scanning results of the affected system. It then asks for users to purchase it once scanning is completed. If users decide to purchase the rogue product, users are directed to a certain website asking for sensitive information, such as credit card numbers.

  TECHNICAL DETAILS

File Size:

344,064 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

12 Apr 2011

Arrival Details

This Trojan may be downloaded by other malware/grayware/spyware from remote sites.

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

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CLASSES_ROOT\.exe\DefaultIcon

HKEY_CLASSES_ROOT\.exe\shell

HKEY_CLASSES_ROOT\exefile

It adds the following registry entries:

HKEY_CLASSES_ROOT\.exe\DefaultIcon
(Default) = "%1"

HKEY_CLASSES_ROOT\.exe\shell\
open\command
(Default) = "{malware path and file name} -a %1 %*"

HKEY_CLASSES_ROOT\.exe\shell\
open\command
IsolatedCommand = "%1 %*"

HKEY_CLASSES_ROOT\.exe\shell\
runas\command
(Default) = "%1 %*"

HKEY_CLASSES_ROOT\.exe\shell\
runas\command
IsolatedCommand = "%1 %*"

HKEY_CLASSES_ROOT\exefile
Content Type = "application/x-msdownload"

HKEY_CLASSES_ROOT\exefile\shell\
open\command
IsolatedCommand = "%1 %*"

HKEY_CLASSES_ROOT\exefile\shell\
runas\command
IsolatedCommand = "%1 %*"

It modifies the following registry entries:

HKEY_CLASSES_ROOT\exefile\shell\
open\command
(Default) = "{malware path and file name} -a "%1" %*"

(Note: The default value data of the said registry entry is "%1" %*.)

Download Routine

This Trojan connects to the following malicious URLs:

  • http://{BLOCKED}nedubuc.com

Other Details

This Trojan installs a fake antivirus/antispyware software.

It poses as an antispyware application that displays deceptive warnings and misleading scan results. It may also add other applications which it detects upon its installation.

It displays fake alerts that warn users of infection. It also displays fake scanning results of the affected system. It then asks for users to purchase it once scanning is completed. If users decide to purchase the rogue product, users are directed to a certain website asking for sensitive information, such as credit card numbers.

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

7.968.09

FIRST VSAPI PATTERN DATE:

12 Apr 2011

Step 1

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

Step 2

Identify and terminate files detected as TROJ_FAKEAV.BYL

[ Learn More ]
  1. For Windows 98 and ME users, 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 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_CLASSES_ROOT\.exe
    • DefaultIcon
  • In HKEY_CLASSES_ROOT\.exe
    • shell
  • In HKEY_CLASSES_ROOT
    • exefile

Step 4

Restore this modified 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_CLASSES_ROOT\exefile\shell\open\command
    • From: (Default) = "{malware path and file name} -a %1 %*"
      To: (Default) = ""%1 %*"

Step 5

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