TROJ_RANSOM.FA

October 31, 2012
 ALIASES:

TrojanDownloader:Win32/Troxen!rts (Microsoft); Generic Downloader.x!ggb (McAfee); Trojan Horse (Symantec); Trojan-Ransom.Win32.PornoBlocker.af (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt)

 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:

59,904 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

31 Oct 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 modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "{malware path and file name}.exe"

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

Other System Modifications

This Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
AFD

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
AppMgmt

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
Base

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
Boot Bus Extender

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
Boot file system

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
Browser

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
CryptSvc

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
DcomLaunch

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
Dhcp

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
dmadmin

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
dmboot.sys

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
dmio.sys

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
dmload.sys

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
dmserver

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
DnsCache

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
EventLog

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
File system

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
Filter

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
HelpSvc

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
ip6fw.sys

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
ipnat.sys

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
LanmanServer

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
LanmanWorkstation

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
LmHosts

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
Messenger

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
NDIS

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
NDIS Wrapper

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
Ndisuio

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
NetBIOS

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
NetBIOSGroup

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
NetBT

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
NetDDEGroup

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
Netlogon

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
NetMan

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
Network

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
NetworkProvider

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
NtLmSsp

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
PCI Configuration

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
PlugPlay

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
PNP Filter

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
PNP_TDI

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
Primary disk

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
rdpcdd.sys

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
rdpdd.sys

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
rdpwd.sys

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
rdsessmgr

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
RpcSs

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
SCSI Class

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
sermouse.sys

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
SharedAccess

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network_\
sr.sys

Dropping Routine

This Trojan drops the following files:

  • %System Root%\xFoLOOOSErs.txt

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.300

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

Identify and delete files detected as TROJ_RANSOM.FA using either the Startup Disk or Recovery Console

[ 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_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot
    • Network_
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • AFD
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • AppMgmt
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • Base
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • Boot Bus Extender
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • Boot file system
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • Browser
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • CryptSvc
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • DcomLaunch
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • Dhcp
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • dmadmin
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • dmboot.sys
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • dmio.sys
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • dmload.sys
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • dmserver
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • DnsCache
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • EventLog
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • File system
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • Filter
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • HelpSvc
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • ip6fw.sys
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • ipnat.sys
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • LanmanServer
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • LanmanWorkstation
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • LmHosts
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • Messenger
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • NDIS
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • NDIS Wrapper
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • Ndisuio
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • NetBIOS
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • NetBIOSGroup
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • NetBT
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • NetDDEGroup
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • Netlogon
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • NetMan
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot_
    • Network
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • NetworkProvider
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • NtLmSsp
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • PCI Configuration
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • PlugPlay
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • PNP Filter
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • PNP_TDI
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • Primary disk
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • rdpcdd.sys
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • rdpdd.sys
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • rdpwd.sys
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • rdsessmgr
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • RpcSs
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • SCSI Class
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • sermouse.sys
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • SharedAccess
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot\Network_
    • sr.sys

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: Shell = "{malware path and file name}.exe"
      To: Shell = ""Explorer.exe""

Step 5

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.
  • %System Root%\xFoLOOOSErs.txt

Step 6

Scan your computer with your Trend Micro product to delete files detected as TROJ_RANSOM.FA. 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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