arrow_back
search
close

WORM_KELIHOS.ACT

September 07, 2013
 Analysis by: Anthony Joe Melgarejo
 ALIASES:

Backdoor:Win32/Kelihos.F (Microsoft), PWS-FASY!9F5C2400CE8D (McAfee), Trojan.Win32.Winwebsec.mdc (v) (Sunbelt), TR/Urausy.JH.8 (Antivir), Backdoor.Win32.Kelihos (Ikarus),

 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: Worm

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This worm 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:

818,688 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

23 May 2013

Arrival Details

This worm 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 worm adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
SonyAgent = "{Malware Path and File Name}"

Other System Modifications

This worm adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
ProxyServer = "http=127.0.0.1:8888;https=127.0.0.1:8888;"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
ProxyOverride = "<-loopback>"

It modifies the following registry entries:

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

(Note: The default value data of the said registry entry is 0.)

It creates the following registry entry(ies) to bypass Windows Firewall:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandProfle\AuthorizedApplications\
List
{Malware path and file name} = "{Malware path and file name}:*:Enabled:Promo"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandProfle\GloballyOpenPorts\
List
{random number 1}:TCP = "{random number 1}:TCP:*:Enabled:Promo"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandProfle\GloballyOpenPorts\
List
{random number 2}:UDP = "{random number 2}:UDP:*:Enabled:Promo"

Propagation

This worm drops the following copy(ies) of itself in all removable drives:

  • game.exe

Other Details

This worm connects to the following possibly malicious URL:

  • {random IP addresses}

It drops the following file(s)/component(s):

  • {removable drive}:\Shortcut to game.lnk - points to malware copy {removable drive}:\game.exe

NOTES:

It drops shortcut files pointing to the copy of itself in removable drives. These dropped .LNK files use the names of the folders located on the said drives for their file names. It then sets the attributes of the original folders to Hidden to trick the user into clicking the .LNK files.

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

9.936.05

FIRST VSAPI PATTERN DATE:

23 May 2013

VSAPI OPR PATTERN File:

9.937.00

VSAPI OPR PATTERN Date:

24 May 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

Scan your computer with your Trend Micro product and note files detected as WORM_KELIHOS.ACT

Step 3

Restart in Safe Mode

[ Learn More ]

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
    • SonyAgent = "{Malware Path and File Name}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandProfle\AuthorizedApplications\List
    • {Malware path and file name} = "{Malware path and file name}:*:Enabled:Promo"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandProfle\GloballyOpenPorts\List
    • {random number 1}:TCP = "{random number 1}:TCP:*:Enabled:Promo"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandProfle\GloballyOpenPorts\List
    • {random number 2}:UDP = "{random number 2}:UDP:*:Enabled:Promo"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • ProxyServer = "http=127.0.0.1:8888;https=127.0.0.1:8888;"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • ProxyOverride = "<-loopback>"

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
    • From: ProxyEnable = "1"
      To: ProxyEnable = "0"

Step 6

Search and delete this file

[ 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.  
  • {removable drive}:\Shortcut to game.lnk

Step 7

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


Did this description help? Tell us how we did.