TSPY_ZBOT.YUNAW

January 12, 2015
 Modified by: Francis Xavier Antazo
 ALIASES:

PWS:Win32/Zbot (Microsoft),Win32/Spy.Zbot.AAU trojan (NOD32),Trojan-Spy.Win32.Zbot.sioc (Kaspersky)

 PLATFORM:

Windows

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

  • Threat Type: Spyware

  • Destructiveness: No

  • Encrypted: Yes

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

It hides files, processes, and/or registry entries.

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

  TECHNICAL DETAILS

File Size:

845,824 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

20 Mar 2014

Payload:

Hides files and processes, Drops files, 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 component file(s):

  • %User Temp%\{random filename 3}.bat

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It drops the following non-malicious files:

  • %Application Data%\Microsoft\Address Book\{user name}.wab
  • %Application Data%\{random filename 2}.{random}

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It drops the following copies of itself into the affected system:

  • %User Temp%\{random folder name}\{random filename 1}.exe - (modified copy)

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It creates the following folders:

  • %Application Data%\Microsoft\Address Book
  • %User Temp%\{random folder name}

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.. %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

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

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

  • Local\{GUID}
  • Global\{GUID}

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""

Other System Modifications

This spyware adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
{random}

HKEY_CURRENT_USER\Software\Microsoft\
WAB

HKEY_CURRENT_USER\Software\Microsoft\
WAB\WAB4

HKEY_CURRENT_USER\Software\Microsoft\
WAB\WAB4\Wab File Name

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
{random}
{random} = "{random}"

HKEY_CURRENT_USER\Software\Microsoft\
WAB\WAB4
OlkContactRefresh = "0"

HKEY_CURRENT_USER\Software\Microsoft\
WAB\WAB4
OlkFolderRefresh = "0"

HKEY_CURRENT_USER\Software\Microsoft\
WAB\WAB4\Wab File Name
(Default) = "%Application Data%\Microsoft\Address Book\{user name}.wab"

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

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}"

Rootkit Capabilities

This spyware hides files, processes, and/or registry entries.

Download Routine

This spyware connects to the following URL(s) to download its configuration file:

  • http://{random generated URL}

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 cerificates

Other Details

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

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

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

  • %System%\driver\{random}.sys - detected as RTKT_NECURS.RBC

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

NOTES:

This spyware attempts to download its configuration file by connecting to randomly generated URL. The configuration file may contain URLs where it downloads an updated copy of itself and where it sends its gathered information. It may also contain URLs of its target online banking and finance-related sites from where it steals the information.

It also collects information when it finds the following strings in certain applications:

  • 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

This spyware attempts to connect to the following URLs via UDP to download the URL that contains the configuration file:

  • {BLOCKED}.{BLOCKED}.14.70:2106
  • {BLOCKED}.{BLOCKED}.143.176:9551
  • {BLOCKED}.{BLOCKED}.162.34:7972
  • {BLOCKED.{BLOCKED}.40.64:5693
  • {BLOCKED}.{BLOCKED}.71.137:1193
  • {BLOCKED}.{BLOCKED}.77.86:5049
  • {BLOCKED}.{BLOCKED}.34.229:3957
  • {BLOCKED}.{BLOCKED}.148.169:6781
  • {BLOCKED}.{BLOCKED}.45.40:6589
  • {BLOCKED}.{BLOCKED}.56.2:4283
  • {BLOCKED}.{BLOCKED}.192.140:4392
  • {BLOCKED}.{BLOCKED}.110.77:4673
  • {BLOCKED}.{BLOCKED}.208.136:8656
  • {BLOCKED}.{BLOCKED}.111.58:2058
  • {BLOCKED}.{BLOCKED}.60.98:3921
  • {BLOCKED}.{BLOCKED}.66.193:2453
  • {BLOCKED}.{BLOCKED}.80.46:3736

  SOLUTION

Minimum Scan Engine:

9.700

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

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

    • RTKT_NECURS.RBC

Step 5

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_CURRENT_USER\Software\Microsoft
    • {random}
  • In HKEY_CURRENT_USER\Software\Microsoft
    • WAB

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\GloballyOpenPorts\List
    • {port1}:UDP = "{port1}:UDP:*:Enabled:UDP {port1}"
  • In HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\GloballyOpenPorts\List
    • {port2}:TCP = "{port2}:TCP:*:Enabled:TCP {port2}"

Step 7

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.
  • %Application Data%\Microsoft\Address Book
  • %User Temp%\{random folder name}

Step 8

Search and delete these files

[ 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.
  • %Application Data%\{random filename 2}.{random}
  • %User Temp%\{random filename 3}.bat

Step 9

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