Ozdok

Mega-D, also known as Ozdok, was a large spam botnet active in the late 2000s. It was operated as part of the criminal spam ecosystem and was associated with command-and-control infrastructure hosted by providers that also serviced other major spam botnets of the period. Contemporary reporting placed its bot population at roughly 120,000 infected systems, making it one of the more significant spam-distribution platforms in operation at the time.

Mega-D primarily targeted Windows systems and functioned as a botnet used for bulk unsolicited email operations. Its known role in the ecosystem was large-scale spam delivery rather than a more specialized payload such as ransomware or banking theft. It is frequently discussed alongside other major spam botnets including Rustock, Srizbi, and Cutwail, and it was significant enough to be named in industry takedown efforts against spam infrastructure.

The malware’s most strongly supported characteristics are its use as a centrally controlled spam botnet and its dependence on external command-and-control hosting. It was part of the broader wave of botnets that relied on resilient hosting arrangements and large numbers of compromised endpoints to sustain spam campaigns at scale. No high-confidence evidence in the supplied material supports more specific delivery vectors or additional capabilities beyond spam-botnet operation.