Analysis by: Abraham Latimer Camba
ALIASES:

Backdoor:Win32/Caphaw.A (Microsoft), Trojan.Shylock (Symantec), Backdoor.Win32.Caphaw (Sunbelt)

 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:
 INFORMATION EXPOSURE:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This backdoor modifies the Internet Explorer Zone Settings.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size: 311,296 bytes
File Type: EXE
Initial Samples Received Date: 09 Apr 2014

Other System Modifications

This backdoor adds the following registry entries:

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
DisableCachingOfSSLPages = "0"

Web Browser Home Page and Search Page Modification

This backdoor modifies the Internet Explorer Zone Settings.

Other Details

This backdoor connects to the following possibly malicious URL:

  • {BLOCKED}.[BLOCKED}.117.73
  • {BLOCKED}.{BLOCKED}.159.106
  • {BLOCKED}.{BLOCKED}.23.43
  • {BLOCKED}.{BLOCKED}.100.140
  • {BLOCKED}.{BLOCKED}.102.15
  • {BLOCKED}.{BLOCKED}.66.132
  • {BLOCKED}.{BLOCKED}.85.16
  • {BLOCKED}q.cc
  • {BLOCKED}o.su

It deletes itself after execution.

  SOLUTION

Minimum Scan Engine: 9.700
FIRST VSAPI PATTERN FILE: 10.718.05
FIRST VSAPI PATTERN DATE: 10 Apr 2014
VSAPI OPR PATTERN File: 10.719.00
VSAPI OPR PATTERN Date: 11 Apr 2014

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

Restart in Safe Mode

[ Learn More ]

Step 3

Reset Internet security settings

[ 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_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • NoProtectedModeBanner = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • DisableCachingOfSSLPages = "0"

Step 5

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