TROJ_AGENT.BDXC


 ALIASES:

Trojan-Downloader.Win32.Agent.gywt (Kaspersky)

 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.

  TECHNICAL DETAILS

File Size:

32,768 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

01 Dec 2012

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.

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
winhelp = "{malware path and file name}"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\InformationBar

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\IntelliForms

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\InformationBar
FirstTime = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\IntelliForms
AskUser = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
FormSuggest PW Ask = "no"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
WarnOnZoneCrossing = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
WarnOnPostRedirect = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
WarnOnHTTPSToHTTPRedirect = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
WarnonBadCertRecving = "0"

HKEY_CURRENT_USER\Software\Policies\
Microsoft\Internet Explorer\Main
DisableFirstRunCustomize = "2"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
IEHardenIENoWarn = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
IEHardenIENoWarn = "0"

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\3
1601 = "0"

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\3
1609 = "0"

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

It deletes the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
ZoneMap\EscDomains\myblog.yahoo.com\
tw

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
ZoneMap\EscDomains\myblog.yahoo.com

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.300

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

Restart in Safe Mode

[ Learn More ]

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_CURRENT_USER\Software\Microsoft\Internet Explorer
    • InformationBar
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer
    • IntelliForms

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\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • winhelp = "{malware path and file name}"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\InformationBar
    • FirstTime = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\IntelliForms
    • AskUser = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • FormSuggest PW Ask = "no"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • WarnOnZoneCrossing = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • WarnOnPostRedirect = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • WarnOnHTTPSToHTTPRedirect = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • WarnonBadCertRecving = "0"
  • In HKEY_CURRENT_USER\Software\Policies\Microsoft\Internet Explorer\Main
    • DisableFirstRunCustomize = "2"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • IEHardenIENoWarn = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • IEHardenIENoWarn = "0"

Step 5

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\3
    • From: 1601 = "0"
      To: 1601 = ""1""
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\3
    • From: 1609 = "0"
      To: 1609 = ""1""

Step 6

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

Step 7

Restore these deleted registry keys/values from backup

*Note: Only Microsoft-related keys/values will be restored. If the malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\ZoneMap\EscDomains\myblog.yahoo.com
    • tw
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\ZoneMap\EscDomains
    • myblog.yahoo.com


Did this description help? Tell us how we did.