Overview
This is a trojan detection. Unlike viruses, trojans do not self-replicate. They are spread manually, often under the premise that they are beneficial or wanted. The most common installation methods involve system or security exploitation, and unsuspecting users manually executing unknown programs. Distribution channels include email, malicious or hacked web pages, Internet Relay Chat (IRC), peer-to-peer networks, etc.
Aliases
Generic Downloader.aw
Characteristics -
The detection for Generic Downloader are for several specific trojan variants, so this description is meant as a general guide. This detection is for trojans which are intended to retrieve and execute files from a remote server. This file will then be automatically executed on the infected machine. The nature of the remote file may vary. As the presence of these trojans and remote files are discovered, sites hosting these files are frequently taken down, so the downloading may cease to function as expected. This may result in empty, 0 byte files or HTML error messages being downloaded instead, or the remote file simply not being downloaded at all.
As new trojans are frequently added to this detection, users are recommended to use the latest engine/DAT combination for optimal detection. Variants are likely to be packed with a PE packer, so enabling the scanning of compressed files will also provide optimal detection.Exact details (filenames, Registry keys, file size) will vary between variants.Typically the downloader will install itself and/or the remote file into the Windows or System directory, and hook system startup via a Registry key such as:
Code:
HKEY_CURRENT_USER\Software\Microsoft\Windows\
CurrentVersion\Run
HKEY_CURRENT_USER\Software\Microsoft\Windows\
CurrentVersion\RunServices
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\
CurrentVersion\Run
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\
CurrentVersion\RunServices
Symptoms -
Desktop firewall program alerting that a foreign application is attempting to access the Internet.
Method of Infection -
This purpose of this trojan is simply to download a file from the Internet and execute it. It does not self-replicate. Downloader trojans are frequently sent in spammed emails designed to entice the recipient into running the file. Other likely distribution channels for this trojan include via IRC, via peer-to-peer file-sharing networks, as an attachment in newsgroup postings, etc. Trojans may also be received as a result of poor security practices (weak username/password combination on open shares, lack of/or misconfigured firewall protection), or unpatched and vulnerable systems.
Removal -
All Users:
Use current engine and DAT files for detection and removal.
Modifications made to the system Registry and/or INI files for the purposes of hooking system startup, will be successfully removed if cleaning with the recommended engine and DAT combination (or higher).
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