- Journal Article
Rights / licenseCreative Commons Attribution 2.0 Generic
The manual forensics investigation of security incidents is an opaque process that involves the collection and correlation of diverse evidence. In this work we first conduct a complex experiment to expand our understanding of forensics analysis processes. During a period of 4 weeks, we systematically investigated 200 detected security incidents about compromised hosts within a large operational network. We used data from four commonly used security sources, namely Snort alerts, reconnaissance and vulnerability scanners, blacklists, and a search engine, to manually investigate these incidents. Based on our experiment, we first evaluate the (complementary) utility of the four security data sources and surprisingly find that the search engine provided useful evidence for diagnosing many more incidents than more traditional security sources, i.e., blacklists, reconnaissance, and vulnerability reports. Based on our validation, we then identify and make publicly available a list of 165 good Snort signatures, i.e., signatures that were effective in identifying validated malware without producing false positives. In addition, we analyze the characteristics of good signatures and identify strong correlations between different signature features and their effectiveness, i.e., the number of validated incidents in which a good signature is identified. Based on our experiment, we finally introduce an IDS signature quality metric that can be exploited by security specialists to evaluate the available rulesets, prioritize the generated alerts, and facilitate the forensics analysis processes. We apply our metric to characterize the most popular Snort rulesets. Our analysis of signatures is useful not only for configuring Snort but also for establishing best practices and for teaching how to write new IDS signatures Show more
Journal / seriesEURASIP Journal on Information Security
Pages / Article No.
SubjectRegular expression; Good signature; Complexity feature; Domain name system; Security incident
Organisational unit03234 - Plattner, Bernhard (emeritus)
MoreShow all metadata