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TSPY_ZBOT.YYDBZ

October 04, 2014
 Analysis by: Jaime Benigno Reyes
 ALIASES:

PWS:Win32/Zbot (Microsoft); Trojan-Dropper.Win32.Necurs.txz (Kaspersky)

 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:

Dropped by other malware, Downloaded from the Internet


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 steals certain information from the system and/or the user.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

202,048 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

17 Sep 2014

Payload:

Connects to URLs/IPs

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 drops the following copies of itself into the affected system and executes them:

  • %User Temp%\{random folder name}\{random filename 1}.exe

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

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

  • %System%\drivers\{random filename 2}.sys - detected as RTKT_NECURS.RBC

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

It drops the following non-malicious files:

  • %AppDataLocal%\{random filename 3}.{random extension}

(Note: %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local on Windows Vista and 7.)

It creates the following folders:

  • %User Temp%\{random folder name}

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It 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
{random filename 1} = "%User Temp%\{random folder name}\{random filename 1}.exe"

It registers its dropped component as a system service to ensure its automatic execution at every system startup. It does this by creating the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random filename 2}
DisplayName = "{random filename 1}.exe"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random filename 2}
ErrorControl = "0"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random filename 2}
ImagePath = "\??\%System%\drivers\{random filename 2}.sys"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random filename 2}
Start = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random filename 2}\Security
Security = "{hex value}"

It registers its dropped component as a system service to ensure its automatic execution at every system startup. It does this by creating the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random filename 2}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random filename 2}\Security

Other System Modifications

This spyware adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
{random}

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

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\GloballyOpenPorts\
List
{random port 1}:UDP = "{random port 1}:UDP:*:Enabled:UDP {random port 1}"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\GloballyOpenPorts\
List
{random port 2}:TCP = "{random port 2}:TCP:*:Enabled:TCP {random port 2}"

Propagation

This spyware does not have any propagation routine.

Backdoor Routine

This spyware does not have any backdoor routine.

Information Theft

This spyware steals the following information:

  • 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 cerificate

Stolen Information

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

  • http://{BLOCKED}wslxpvvphxnjij.biz
  • http://{BLOCKED}uzllfeyhcuzddpfafuyp.ru
  • http://{BLOCKED}buzttmrciuomjwrcjr.info
  • http://{BLOCKED}dmzswgexoqzlfaddqvgjuw.biz
  • http://{BLOCKED}nk.fbi-cyber.net
  • http://{BLOCKED}rgdqkfdujrfqwkhapbsg.org
  • http://{BLOCKED}gytwxwkfbyldaqea.info
  • http://{BLOCKED}.{BLOCKED}.4.71
  • http://{BLOCKED}.{BLOCKED}.43.69

Other Details

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

  • http://google.com
  • http://bing.com

It deletes itself after execution.

NOTES:

It collects information from certain financial/banking programs that contain the following strings:

  • bancline
  • bankman
  • cruisenet
  • dirclt32.exe
  • episys
  • fastdoc
  • fdmaster.exe
  • fidelity
  • gplusmain
  • jack henry
  • launchpadshell.exe
  • micrsolv
  • pcsws.exe
  • prologue.exe
  • silverlake
  • tellerplus
  • v48d0250s1
  • vantiv
  • wtng.exe

It does not have rootkit capabilities.

It does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

11.152.02

FIRST VSAPI PATTERN DATE:

16 Sep 2014

VSAPI OPR PATTERN File:

11.153.00

VSAPI OPR PATTERN Date:

17 Sep 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

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

Remove malware/grayware files dropped/downloaded by TSPY_ZBOT.YYDBZ. (Note: Please skip this step if the threats listed below have already been removed.)

Step 4

Scan your computer with your Trend Micro product and note files detected as TSPY_ZBOT.YYDBZ

Step 5

Restart in Safe Mode

[ Learn More ]

Step 6

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 filename 1} = "%User Temp%\{random folder name}\{random filename 1}.exe"
  • 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\GloballyOpenPorts\List
    • {random port 1}:UDP = "{random port 1}:UDP:*:Enabled:UDP {random port 1}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\GloballyOpenPorts\List
    • {random port 2}:TCP = "{random port 2}:TCP:*:Enabled:TCP {random port 2}"

Step 7

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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • {random filename 2}
  • In HKEY_CURRENT_USER\Software\Microsoft
    • {random}

Step 8

Search and delete these folders

[ 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.
  • %User Temp%\{random folder name}

Step 9

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

The following created files/folders/registry keys/registry entries cannot be identified by the user since there are no reference values in the created key. The only way it can be identified is by comparing the present system information with a backup. Note that the said components do not have to be deleted since it won't be harmful to the system.

  • HKEY_CURRENT_USER\Software\Microsoft\{random}


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