ALIASES:

Trojan:Win32/Dynamer!dtc (Microsoft); Generic.dx!bc3t (McAfee); Downloader (Symantec); Trojan.Win32.Inject.cejr (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Trojan.Generic.7221028 (FSecure)

 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: 28,672 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 18 Apr 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_CURRENT_USER\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

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\
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\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
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\ddns.us\
pic-yahoo

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
ZoneMap\EscDomains\ddns.us

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\sys.exe

(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.)

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}1.218.86:443/eazda.php?id=0273631161679F11EE
  • http://{BLOCKED}1.218.86:8080/eazda.php?id=0322341161679F11EE
  • http://{BLOCKED}1.218.86:110/eazda.php?id=0106151161679F11EE
  • http://{BLOCKED}60.218:80/eazda.php?id=0269791161679F11EE
  • http://{BLOCKED}60.218:110/eazda.php?id=0027121161679F11EE
  • http://abianshabi.{BLOCKED}s.com:80/eazda.php?id=0189441161679f11ee
  • http://abianshabi.{BLOCKED}s.com:443/eazda.php?id=0043261161679f11ee
  • http://abianshabi.{BLOCKED}s.com:8080/eazda.php?id=0087751161679f11ee

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.200

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

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

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_CURRENT_USER\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\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\Microsoft\Windows\CurrentVersion\Internet Settings
    • IEHardenIENoWarn = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • IEHardenIENoWarn = "0"

Step 5

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

Step 6

Search and delete this file

[ 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.
  • %User Temp%\sys.exe

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_SIMBOT.B. 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 8

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\ddns.us
    • pic-yahoo
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\ZoneMap\EscDomains
    • ddns.us


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