Analysis by: Andrei Castillo
ALIASES:

TrojanDownloader:Win32/Upatre.A(Microsoft), Trojan-Spy.Zbot(Ikarus), Win32/TrojanDownloader.Small.AAB trojan(NOD32), Trojan.Zbot(Norton), Trojan.Win32.Generic!BT(Sunbelt), TR/Rogue.AI.10211(Antivir), Trojan.Downloader.Small.ABNB(BitDefender), Troj/Agent-AEIE(Sophos_Lite), W32/Trojan3.GGX (exact)(FPROT)

 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: Dropped by other malware, Downloaded from the Internet

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 the initially executed copy of itself.

  TECHNICAL DETAILS

Ports: TCP Port 443
File Size: 20,112 bytes
Memory Resident: No
Initial Samples Received Date: 21 Oct 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%\hhcbrnaff.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.)

Other System Modifications

This Trojan modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
MigrateProxy = "1"

(Note: The default value data of the said registry entry is "0".)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
ProxyEnable = "0"

(Note: The default value data of the said registry entry is "0" - Modifies value if "1"..)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
ZoneMap
ProxyBypass = "1"

(Note: The default value data of the said registry entry is "0".)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
ZoneMap
IntranetName = "1"

(Note: The default value data of the said registry entry is "0".)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
ZoneMap
UNCAsIntranet = "1"

(Note: The default value data of the said registry entry is "0".)

Download Routine

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

  • {BLOCKED}l.com/images/ho15.exe
  • {BLOCKED}ectric.com/images/doto15.exe
  • {BLOCKED}week.com/photo/mor03.exe
  • {BLOCKED}der.co.uk/config/1m0r.exe
  • {BLOCKED}hasta.com/hasta/ho7.exe
  • {BLOCKED}mers.org/wp-config/rch8.exe
  • {BLOCKED}week.com
  • https://{BLOCKED}rts.com/images/U2.exe
  • https://{BLOCKED}3.com/wp-content/uploads/2012/07/dtn21.exe

It saves the files it downloads using the following names:

  • %User Temp%\hhgnrddkjee.exe - detected as TSPY_ZBOT.SMZ8.

(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 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 the initially executed copy of itself

NOTES:
It downloads a malicious file detected as TSPY_ZBOT.SMZ8 through HTTPS connection.

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 10.357.00
FIRST VSAPI PATTERN DATE: 21 Oct 2013
VSAPI OPR PATTERN File: 10.357.00
VSAPI OPR PATTERN Date: 21 Oct 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

Restart in Safe Mode

[ Learn More ]

Step 3

Search and delete this file

[ 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.  
  • %User Temp%\hhcbrnaff.exe

Step 4

Restore this modified 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\Internet Settings
    • From: MigrateProxy = "1"
      To: MigrateProxy = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • From: ProxyEnable = "0"
      To: ProxyEnable = "0" - restore to 1 if previous value is 1.
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\ZoneMap
    • From: ProxyBypass = "1"
      To: ProxyBypass = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\ZoneMap
    • From: IntranetName = "1"
      To: IntranetName = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\ZoneMap
    • From: UNCAsIntranet = "1"
      To: UNCAsIntranet = "0"

Step 5

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

    • TSPY_ZBOT.SMZ8

Step 6

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