Analysis by: Rika Joi Gregorio
ALIASES:

TrojanDownloader:Win32/Upatre.A(Microsoft), Trojan.Zbot(Symantec), Trojan.Win32.Badur(Ikarus), W32/Bublik.AAB!tr(Fortinet), Win32/TrojanDownloader.Small.AAB trojan(Eset)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

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

This Trojan 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 downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size: 22,016 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 19 Nov 2013
Payload: Downloads files

Arrival Details

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

  • %User Temp%\budha.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.)

Download Routine

This Trojan connects to the following website(s) to download and execute a malicious file:

  • https://{BLOCKED}io.com/img/conf.exe

It saves the files it downloads using the following names:

  • %User Temp%\kilf.exe - detected as TSPY_ZBOT.TB
  • %Temporary Internet Files%\Content.IE5\{random folder}\conf[1].exe - detected as TSPY_ZBOT.TB

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

It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

Other Details

This Trojan deletes itself after execution.

  SOLUTION

Minimum Scan Engine: 9.700
FIRST VSAPI PATTERN FILE: 10.444.07
FIRST VSAPI PATTERN DATE: 01 Dec 2013
VSAPI OPR PATTERN File: 10.445.00
VSAPI OPR PATTERN Date: 01 Dec 2013

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

Remove malware/grayware files dropped/downloaded by TROJ_UPATRE.TB

     
    • TSPY_ZBOT.TB

Step 3

Scan your computer with your Trend Micro product to delete files detected as TROJ_UPATRE.TB. 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:

To delete %Temporary Internet Files%\Content.IE5\{random folder}\conf[1].exe:

1. Go to Start

2. Search

3. Click all files and folders and input the following information:

  • All or part of the file name, conf[1].exe

    • 4. Look in %Temporary Internet Files%\Content.IE5

    5. Once located, select the file then press SHIFT+DELETE


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