TSPY_ZBOT.EZN
PWS:Win32/Zbot (Microsoft)
Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
Threat Type: Spyware
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
Spammed via email, 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 executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.
It deletes the initially executed copy of itself.
TECHNICAL DETAILS
492,904 bytes
EXE
Yes
11 Apr 2014
Drops files, Downloads files
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:
- %User Temp%\{random folder}\{random file name}.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):
- %User Temp%\{random file name 3}.bat - used to delete the initially executed copy
(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 creates the following folders:
- %User Temp%\{random folder}
(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 injects codes into the following process(es):
- explorer.exe
It terminates the execution of the copy it initially executed and executes the copy it drops instead.
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 string} = "%User Temp%\{random folder}\{random file name}.exe"
Other System Modifications
This spyware adds the following registry keys:
HKEY_CURRENT_USER\Software\Microsoft\
{random key}
Dropping Routine
This spyware drops the following files:
- %System%\drivers\{random file name 2}.sys - detected by Trend Micro as RTKT_NECURS.BGSG
(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)
It executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.
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 deletes the initially executed copy of itself
NOTES:
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.
This spyware may also gather the following information from the affected system:
- Data (URLs) on cookie files
- 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
This spyware 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 name with the format {pseudorandom characters}.{extension}.
SOLUTION
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 3
Scan your computer with your Trend Micro product and note files detected as TSPY_ZBOT.EZN
Step 4
Restart in Safe Mode
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
- {random string} = "%User Temp%\{random folder}\{random file name}.exe"
- {random string} = "%User Temp%\{random folder}\{random file name}.exe"
Step 6
Search and delete this folder
- %User Temp%\{random folder}
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TSPY_ZBOT.EZN. 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 8
The following created registry key(s) 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 of the system registry. Note that the said key(s) do not have to be deleted since it won't be harmful to the system:
- HKEY_CURRENT_USER\Software\Microsoft\{random key}
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