TROJ_RANSOM.EHA

 Analysis by: Adrian Cofreros

 ALIASES:

Trojan.Win32.Buzus.lawo(Kaspersky),Win32/Filecoder.NAH trojan(NOD32),Trojan horse Ransomer.TD(AVG)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

 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:

518,375 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

03 Jul 2013

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 files:

  • %System Root%\ProgramData\local\aescrypter.exe
  • %System Root%\ProgramData\local\svchost.exe
  • %System Root%\ProgramData\local\undxkpwvlk.dll
  • %System Root%\ProgramData\local\vpkswnhisp.dll
  • %System%\csrsstub.exe
  • %System%\dcomcnfgui.exe
  • %System%\tcpsvcss.exe
  • %System%\tracerpts.exe
  • %System%\ucsvcsh.exe
  • %System%\wcmtstcsys.sss
  • %System Root%\how to decrypt aes files.lnk
  • All Users’ %Desktop%\how to decrypt aes files.lnk
  • %System Root%\decrypt\decrypt.exe

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.. %Desktop% is the desktop folder, where it usually is C:\Documents and Settings\{user name}\Desktop in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\Desktop in Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It creates the following folders:

  • %System Root%\decrypt
  • %System Root%\ProgramData\local
  • %Application Data%\WinRAR

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Other System Modifications

This Trojan deletes the following files:

  • Files with any of the following extension:
    • .fh
    • .bkf
    • .qbb
    • .tib
    • .001
    • .113
    • .abf
    • .abk
    • .as4
    • .ate
    • .ati
    • .bac
    • .bak
    • .bck
    • .bcm
    • .bk1
    • .bkc
    • .bkp
    • .bks
    • .bpa
    • .bpb
    • .bps
    • .bup
    • .dna
    • .fbf
    • .fbw
    • .ful
    • .gho
    • .ipd
    • .jbk
    • .kb2
    • .mig
    • .nba
    • .nbf
    • .nbu
    • .nb7
    • .nbk
    • .nbs
    • .npf
    • .nps
    • .nrs
    • .oeb
    • .old
    • .qbk
    • .qic
    • .rbc
    • .rbf
    • .rdb
    • .rrr
    • .sbb
    • .sn1
    • .sn2
    • .spf
    • .spi
    • .stg
    • .tbk
    • .uci
    • .v2i
    • .wbb

It adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\netprofms\Enum

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\netprofms\Security

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WdiServiceSysHost\Enum

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WdiServiceSysHost\Security

HKEY_CURRENT_USER\Software\WinRAR SFX

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\netprofms

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WdiServiceSysHost

It adds the following registry entries:

HKEY_CURRENT_USER\Software\WinRAR SFX
{%System Root%}%%WINDOWS%system32% = "%System%"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
svchost = "%System Root%\ProgramData\local\svchost.exe"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\netprofms
Type = "10"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\netprofms
Start = "2"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\netprofms
ErrorControl = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\netprofms
ImagePath = "%System%\ucsvcsh.exe"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\netprofms
DisplayName = "Network List System Service"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\netprofms
ObjectName = "LocalSystem"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\netprofms
Description = "Identifies the networks to which the computer has connected, collects, stores properties for these networks, and notifies applications when these properties change."

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\netprofms\Security
Security = "{hex values 1}"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\netprofms\Enum
0 = "Root\LEGACY_NETPROFMS\0000"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\netprofms\Enum
Count = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\netprofms\Enum
NextInstance = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WdiServiceSysHost
Start = "2"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WdiServiceSysHost
ErrorControl = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WdiServiceSysHost
Type = "10"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WdiServiceSysHost
ImagePath = "%System%\dcomcnfgui.exe"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WdiServiceSysHost
DisplayName = "Diagnostic Service System Host"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WdiServiceSysHost
ObjectName = "LocalSystem"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WdiServiceSysHost
Description = "The Diagnostic Service System Host is used by the Diagnostic Policy Service to host diagnostics that need to run in a Local Service context. If this service is stopped, any diagnostics that depend on it will no longer function."

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WdiServiceSysHost\Security
Security = "{hex values 2}"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WdiServiceSysHost\Enum
0 = "Root\LEGACY_WDISERVICESYSHOST\0000"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WdiServiceSysHost\Enum
Count = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WdiServiceSysHost\Enum
NextInstance = "1"

It modifies the following registry entries:

HKEY_USERS\.DEFAULT\Software\
Microsoft\Windows\CurrentVersion\
Explorer\Shell Folders
AppData = "%System Root%\Documents and Settings\LocalService\Application Data"

(Note: The default value data of the said registry entry is %System Root%\Documents and Settings\NetworkService\Application Data.)

It deletes the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\SafeBoot

Other Details

This Trojan encrypts files with the following extensions:

  • .jpeg
  • .docx
  • .xlsx
  • .db
  • .pdf
  • .olk
  • .dat
  • .zip
  • .rar
  • .qbw
  • .jpg
  • .doc
  • .psd
  • .bmp
  • .png
  • .xls
  • .txt
  • .rtf
  • .tif
  • .xml
  • .php
  • .sxg
  • .ods
  • .sql
  • .jpe
  • .$er
  • .4dd
  • .aft
  • .ahd
  • .ask
  • .azz
  • .bib
  • .bok
  • .btr
  • .cdb
  • .cdb
  • .crd
  • .daf
  • .db2
  • .db3
  • .dbc
  • .dbs
  • .dbf
  • .dbv
  • .df1
  • .dp1
  • .dsk
  • .dta
  • .dxl
  • .eco
  • .edb
  • .eql
  • .fcd
  • .fdb
  • .fic
  • .fid
  • .fol
  • .gdb
  • .hdb
  • .his
  • .ihx
  • .jtx
  • .lgc
  • .mdb
  • .mdf
  • .mud
  • .myd
  • .ns2
  • .ns3
  • .ns4
  • .nsf
  • .nyf
  • .odb
  • .ora
  • .owg
  • .pan
  • .pdb
  • .pdb
  • .pdm
  • .phm
  • .pwa
  • .qvd
  • .rsd
  • .sbf
  • .sdb
  • .sdf
  • .tcx
  • .tdt
  • .udb
  • .v12
  • .wdb
  • .xld
  • .zdb
  • .fp7

It renames encrypted files using the following names:

  • {original file name}.aes

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

10.130.09

FIRST VSAPI PATTERN DATE:

03 Jul 2013

VSAPI OPR PATTERN File:

10.131.00

VSAPI OPR PATTERN Date:

04 Jul 2013

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 delete files detected as TROJ_RANSOM.EHA using the Recovery Console

[ Learn More ]

Step 3

Scan your computer with your Trend Micro product and note files detected as TROJ_RANSOM.EHA

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
    • svchost = "%System Root%\ProgramData\local\svchost.exe"

Step 5

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
    • WinRAR SFX
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • netprofms
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • WdiServiceSysHost

Step 6

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_USERS\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders
    • From: AppData = "%System Root%\Documents and Settings\LocalService\Application Data"
      To: AppData = %System Root%\Documents and Settings\NetworkService\Application Data

Step 7

Search and delete these files

[ 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.
  • %System%\csrsstub.exe
  • %System%\tcpsvcss.exe
  • %System%\tracerpts.exe
  • %System Root%\how to decrypt aes files.lnk
  • All Users' %Desktop%\how to decrypt aes files.lnk

Step 8

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %System Root%\decrypt
  • %System Root%\ProgramData\local
  • %Application Data%\WinRAR

Step 9

Scan your computer with your Trend Micro product to delete files detected as TROJ_RANSOM.EHA. 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 10

Restore this deleted registry key/value 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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control
    • SafeBoot

Step 11

Restore files from backup Only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on your computer again.

NOTES:

Delete the following files during the Recovery Console to disable the startup of the malware:

  • %System%\ucsvcsh.exe
  • %System%\dcomcnfgui.exe
  • %System Root%\ProgramData\local\svchost.exe


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