Analysis by: Jed Valderama
ALIASES:

Backdoor:Win32/Caphaw.D (Microsoft), BackDoor-FHI (McAfee), Trojan.Gen (Symantec), Trojan.Win32.Generic!SB.0 (Sunbelt), Mal/EncPk-AER (Sophos)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It is injected into all running processes to remain memory resident.

It connects to a website to send and receive information. However, as of this writing, the said sites are inaccessible.

It modifies the Internet Explorer Zone Settings.

This is the Trend Micro detection for files that exhibit certain behaviors. It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

Ports: TCP Port 443
File Size: Varies
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 18 Aug 2012
Payload: Connects to URLs/IPs, Compromises system security, Collects system information

Arrival Details

This backdoor 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 backdoor drops the following copies of itself into the affected system:

  • User Profile%\Application Data\{random application path}\{random application name}.exe

It is injected into all running processes to remain memory resident.

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random GUID} = "%User Profile%\Application Data\{random application path}\{random application name}.exe"

Other System Modifications

This backdoor adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
NoProtectedModeBanner = "1"

Backdoor Routine

This backdoor connects to the following websites to send and receive information:

  • {BLOCKED}-upd.at/first.php?r={random}
  • {BLOCKED}ervise.cc/first.php?r={random}
  • {BLOCKED}in.su/first.php?r={random}
  • {BLOCKED}tection.su
  • {BLOCKED}d.su
  • cm103.{BLOCKED}2.{BLOCKED}.ponyhost.in

It posts the following information to its command and control (C&C) server:

  • Installed Applications
  • Directory and File List
  • Drive Informations
  • Network Information
  • Username
  • Computername
  • OS Version
  • Hardware Information
  • Running Processes

However, as of this writing, the said sites are inaccessible.

Web Browser Home Page and Search Page Modification

This backdoor modifies the Internet Explorer Zone Settings.

Other Details

This is the Trend Micro detection for:

  • KATSLO malware family

It deletes the initially executed copy of itself

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 9.340.02
FIRST VSAPI PATTERN DATE: 22 Aug 2012

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 BKDR_KATSLO.SMA

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Search and delete the file detected as BKDR_KATSLO.SMA

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden files in the search result.

Step 5

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
    • {random GUID} = "%User Profile%\Application Data\{random application path}\{random application name}.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • NoProtectedModeBanner = "1"

Step 6

Reset Internet security settings

[ Learn More ]

Step 7

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

Scan your computer with your Trend Micro product to delete files detected as BKDR_KATSLO.SMA. 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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