Analysis by: John Karlo Agon

ALIASES:

TrojanSpy:MSIL/Tzeebot.A (Microsoft), a variant of MSIL/Spy.TzeeBot.B (ESET-NOD32), Trojan.Tzeebot (Symantec)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware

This backdoor 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 commands from a remote malicious user, effectively compromising the affected system.

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

However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size: 106,496 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 24 Aug 2015
Payload: Steals information

Arrival Details

This backdoor 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 backdoor drops the following copies of itself into the affected system:

  • %Application Data%\netscp.exe
  • %Application Data%\{filename}.exe_

(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.)

Autostart Technique

This backdoor drops the following file(s) in the Windows User Startup folder to enable its automatic execution at every system startup:

  • %User Startup%\Windows Media Player Tray.lnk

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Documents and Settings\{user}\Start Menu\Programs\Startup on Windows 2000 and XP, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows Vista, 7, and 8.)

Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

  • Replace Files
  • Copy Files
  • Delete Files
  • Upload Files
  • Create and terminate processes

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • http://{BLOCKED}1.{BLOCKED}productupdate.com/DefaultWS.asmx

Dropping Routine

This backdoor drops the following files:

  • %Application Data%\Microsoft\Windows\Last Items\AppID.guid
  • %Application Data%\Microsoft\Windows\Last Items\{Year_month_day_hour_min_secs}k.tmp
  • %User Temp%\{random 8 characters}.tmp
  • %User Temp%\{random 8 characters}.0.cs
  • %User Temp%\{random 8 characters}.dll
  • %User Temp%\{random 8 characters}.cmdline
  • %User Temp%\{random 8 characters}.out
  • %User Temp%\{random 8 characters}.err
  • %User Temp%\CSC10.tmp
  • %User Temp%\RES11.tmp

(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.)

Information Theft

This backdoor steals the following information:

  • User name
  • Running Process
  • IP address
  • Keystroke logs
  • OS Information

Stolen Information

This backdoor sends the data it gathers to the following email addresses via SMTP:

  • {BLOCKED}cAnalyzer@yahoo.com

Other Details

However, as of this writing, the said sites are inaccessible.

NOTES:

The dropped files,added process and registries are dependent on the argument provided by the user.

It may accept any of the following arguments:

  • /y
  • /m
  • /mr
  • wmplayer.exe
  • copy
  • opensesemi
  • /checkall
  • /file1:
  • /maxkf:
  • /emailt:
  • /nomail
  • /dbg

  SOLUTION

Minimum Scan Engine: 9.750
FIRST VSAPI PATTERN FILE: 11.876.01
FIRST VSAPI PATTERN DATE: 25 Aug 2015
VSAPI OPR PATTERN File: 11.877.00
VSAPI OPR PATTERN Date: 26 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

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%\Microsoft\Windows\Last Items\AppID.guid
  • %Application Data%\Microsoft\Windows\Last Items\{Year_month_day_hour_min_secs}k.tmp
  • %User Temp%\{random 8 characters}.tmp
  • %User Temp%\{random 8 characters}.0.cs
  • %User Temp%\{random 8 characters}.dll
  • %User Temp%\{random 8 characters}.cmdline
  • %User Temp%\{random 8 characters}.out
  • %User Temp%\{random 8 characters}.err
  • %User Temp%\CSC10.tmp
  • %User Temp%\RES11.tmp
  • %Application Data%\netscp.exe
  • %Application Data%\{filename}.exe_
  • %User Startup%\Windows Media Player Tray.lnk

Step 5

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