TSPY_ZBOT.YUYAPQ
PWS:Win32/Zbot (Microsoft); Suspicious.Cloud.5 (Symantec); Gen:Variant.Zusy.64046 (BitDefender)
Windows
Threat Type: Spyware
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
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 modifies registry entries to disable the Windows Firewall settings. This action allows this malware to perform its routines without being deteted by the Windows Firewall.
It modifies the Internet Explorer Zone Settings.
It retrieves specific information from the affected system.
TECHNICAL DETAILS
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 non-malicious files:
- %Application Data%\{random filename}.{random extension}
- %Application Data%\Microsoft\Address Book\{user name}.wab
(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 adds the following mutexes to ensure that only one of its copies runs at any one time:
- Global\{GUID}
- Local\{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
Ydeb = "%Application Data%\{random filename}.exe"
Other System Modifications
This spyware adds the following registry keys:
HKEY_CURRENT_USER\Software\Microsoft\
WAB
HKEY_CURRENT_USER\Software\Microsoft\
{random key name}
It modifies the following registry entries to disable the Windows Firewall settings:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\GloballyOpenPorts\
List
{port1}:UDP = "{port1}:UDP:*:Enabled:UDP {port1}"
HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\GloballyOpenPorts\
List
{port2}:TCP = "{port2}:TCP:*:Enabled:TCP {port2}"
Web Browser Home Page and Search Page Modification
This spyware modifies the Internet Explorer Zone Settings.
Information Theft
This spyware retrieves the following information from the affected system:
- 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
Other Details
This spyware connects to the following URL(s) to check for an Internet connection:
- http://www.google.com
- http://www.bing.com
NOTES:
The configuration file may contain URLs where it downloads an updated copy of itself and sends its gathered information. It may also contain URLs of its target online banking and finance-related sites from where it steals information.
It connects to random generated IP addresses. It sends out DNS queries to a randomized domain name with the following extensions:
- .info
- .com
- .biz
- .org
- .net
- .ru
It connects to randomized domain names using the following format:
- {random characters}.{extension}
SOLUTION
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
Step 4
Delete this registry key
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.
- HKEY_CURRENT_USER\Software\Microsoft\WAB
Step 5
Delete this registry value
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
- Ydeb = %Application Data%\{random filename}.exe
- Ydeb = %Application Data%\{random filename}.exe
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\GloballyOpenPorts\List
- {port}:UDP = {port}:UDP:Enabled:UDP {port}
- {port}:UDP = {port}:UDP:Enabled:UDP {port}
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\GloballyOpenPorts\List
- {port}:TCP = {port}:TCP:Enabled:TCP {port}
- {port}:TCP = {port}:TCP:Enabled:TCP {port}
Step 6
Search and delete these files
- %Application Data%\{random filename}.{random extension}
- %Application Data%\Microsoft\Address Book\{user name}.wab
Step 7
Reset Internet security settings
Step 8
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TSPY_ZBOT.YUYAPQ. 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.
NOTES:
The created registry key HKEY_CURRENT_USER\Software\Microsoft\{random key name} 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 keys with a backup if the users have one. Note that the key need not to be deleted since it won't cause the user system any harm.
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