Abstract
Internet worms pose a major threat to Internet infrastructure security, and their destruction causes loss of millions of dollars. Therefore, the networks must be pro-tected as much as possible to avoid losses. In this paper we propose accurate system for signature generation for Zero-day polymorphic worms. We have designed a novel double-honeynet system, which is able to detect new worms that have not been seen before. We apply Princi-pal Component Analysis (PCA) to determine the most significant substrings that are shared between po-lymorphic worm instances. The experimental results show that the PCA has successfully detected polymorphic worms with zero false positives and zero false negatives.