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TSPY_ZBOT.YUYAGF

September 08, 2015
 Analysis by: RonJay Kristoffer Caragay
 ALIASES:

PWS:Win32/Zbot!rfn (Microsoft); Win32/Spy.Zbot.ACB (ESET-NOD32); Zbot.AFRB (AVG); W32/Zbot.ACB!tr.spy (Fortinet)

 PLATFORM:

Windows

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

  • Threat Type: Spyware

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware

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

It does not have any propagation routine.

It does not have any backdoor routine.

It modifies the Internet Explorer Zone Settings.

As of this writing, the said sites are inaccessible.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

307,200 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

08 Sep 2015

Payload:

Connects to URLs/IPs, Steals information

Arrival Details

This spyware 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 spyware adds the following mutexes to ensure that only one of its copies runs at any one time:

  • Local\{GUID}
  • Global\{GUID}

It injects codes into the following process(es):

  • explorer.exe

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{GUID} = "{malware path and filename}.exe"

Other System Modifications

This spyware adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
{random key}

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
{random key}
{random} = "{hex values}"

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
EnableSPDY3_0 = "0"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%Windows%\explorer.exe = "%Windows%\explorer.exe:*:Enabled:Windows Explorer"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%System%\explorer.exe = "%System%\explorer.exe:*:Enabled:Windows Explorer"

Propagation

This spyware does not have any propagation routine.

Backdoor Routine

This spyware does not have any backdoor routine.

Web Browser Home Page and Search Page Modification

This spyware modifies the Internet Explorer Zone Settings.

Download Routine

This spyware downloads an updated copy of itself from the following website(s):

  • https://{BLOCKED}um.net/s186/klj15.exe

As of this writing, the said sites are inaccessible.

Information Theft

This spyware accesses the following site to download its configuration file:

  • https://{BLOCKED}um.net/s186/lkp5.jpg
  • https://{BLOCKED}dic.com/s186/lkp6.jpg
  • https://{BLOCKED}haw.com/s186/lkp7.jpg

Its configuration file contains the following information:

  • URLs where it downloads an updated copy of itself
  • URLs where it sends its gathered information
  • URLs of its target online banking and finance-related sites from where it steals the information

It gathers the following data:

  • Data on cookie files (URLs)
  • Email-related information such as account names, email addresses, passwords, server data, and server port
  • Email information stored in the user's Windows Address Book (WAB) file
  • Online banking credentials
  • Personal digital certificate

Stolen Information

This spyware sends the gathered information via HTTP POST to the following URL:

  • https://{BLOCKED}um.net/s186/zzz.php

Other Details

This spyware connects to the following URL(s) to check for an Internet connection:

  • http://www.yandex.ru

It deletes itself after execution.

NOTES:

It does not have rootkit capabilities.

It does not exploit any vulnerability.

It performs a man-in-the-browser attack, in which codes are injected into the browser in order to access the following URL upon visiting any of the targeted bank-related sites:

  • https://{BLOCKED}ommote.com/gate/script/{BOTID}/JP/{target bank-related URL}/{scriptname}.js

  SOLUTION

Minimum Scan Engine:

9.750

FIRST VSAPI PATTERN FILE:

11.838.04

FIRST VSAPI PATTERN DATE:

06 Aug 2015

VSAPI OPR PATTERN File:

11.839.00

VSAPI OPR PATTERN Date:

07 Aug 2015

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

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {GUID} = "{malware path and filename}.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • WarnonBadCertRecving = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • EnableSPDY3_0 = "0"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • %Windows%\explorer.exe = "%Windows%\explorer.exe:*:Enabled:Windows Explorer"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • %System%\explorer.exe = "%System%\explorer.exe:*:Enabled:Windows Explorer"

Step 5

Reset Internet security settings

[ Learn More ]

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TSPY_ZBOT.YUYAGF. 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 7

Scan your computer with your Trend Micro product to delete files detected as TSPY_ZBOT.YUYAGF. 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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