Trojan-Downloader:W32/Small identifies one of more than 370 variants (as of June 28 2004) in this large malware family. The main characteristics of these programs are:
Many variants are compressed (bya variety of file compressor programs) to reduce their size and hide their contents from the user.
Some Small variants download adware, spyware and searchware (third-party search plugins); others download trojans and backdoors.
Small variants are often silently installed on a user's system via a driveby download when the user visits a malicious website.