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Aliases: TrojanDownloader:Win32/Upatre.A (Microsoft); DDoS-mmile (McAfee); Downloader (Symantec); Trojan.Win32.Bublik.beby (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Trojan horse Zbot.BLP (AVG)
Malware type: Trojan
Destructive: No
Platform: Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
Encrypted: Yes
In the wild: Yes


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

This malware is involved in the CryptoLocker ransomware malicious spam campaign spotted on October 2013. It is the malicious attachment that, when executed, downloads more malware onto the affected system. Users affected by this malware may find certain files and/or documents in their system unusable.

To get a one-glance comprehensive view of the behavior of this Trojan, refer to the Threat Diagram shown below.

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 modifies the Internet Explorer Zone Settings.

It deletes itself after execution.

Technical Details

File size: 22,528 bytes
File type: EXE
Memory resident: No
Initial samples received date: 19 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.

Web Browser Home Page and Search Page Modification

This Trojan modifies the Internet Explorer Zone Settings.

Download Routine

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

  • http://{BLOCKED} via port 443

It saves the files it downloads using the following names:

  • %User Temp%\hfdfjdk.exe - also detected as TSPY_ZBOT.VNA

(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 Details

This Trojan deletes itself after execution.


Minimum scan engine: 9.300
VSAPI OPR Pattern Version: 10.351.00
VSAPI OPR Pattern Release Date: 19 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

Reset Internet privacy settings

[ Learn more ]

Step 3

Scan your computer with your Trend Micro product to delete files detected as TROJ_UPATRE.VNA. 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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Analysis By: Jennifer Gumban

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