Based on our experiment, we describe a number of lessons we learned from the validation of security incidents. In particular, we make three contributions. First, we describe how to leverage four different security data sources to remotely diagnose live infections in a large production network. Second, to delineate the manual investigation process, we evaluate the (complementary) utility of the four data sources. Surprisingly, we find that a search engine was one of the most useful sources in deciding if a suspicious host was infected, providing useful evidence that led to a positive diagnosis in 54.5% of the cases. Reconnaissance and vulnerability reports were useful in fewer cases, but helped diagnose more sophisticated malware, whereas blacklists were useful only for 10.5% of the incidents. In addition, we report which combinations of
sources helped diagnose different types ofmalware. Third, we make available a list of 165 Snort signatures that were effective in detecting validated malware without producing false positives. We analyze the differences between good and regular Snort signatures and observe that good signatures tend to use offsets, regular expressions, fixed packet sizes, and specific destination ports much more often than regular signatures. This shows that unlike common best practices for keeping IDS signatures simple, complexity in the case of signature writing is a virtue. In addition, we find that different signature features exhibit strong correlations with the effectiveness of a good signature, i.e., the number of validated incidents it detected. Based on this, we introduce a novel signature quality metric that can be used by security specialists to evaluate the available rulesets, prioritize the generated alerts, and facilitate the forensics analysis processes. Finally, we apply our
metric to the most popular signature rulesets, i.e., to the Vulnerability Research Team, the Emerging Threats [1], the Bleeding Edge [2], and the SRI Bothunter [3] rulesets, and highlight their differences.
Based on our experiment, we describe a number of lessons we learned from the validation of security incidents. In particular, we make three contributions. First, we describe how to leverage four different security data sources to remotely diagnose live infections in a large production network. Second, to delineate the manual investigation process, we evaluate the (complementary) utility of the four data sources. Surprisingly, we find that a search engine was one of the most useful sources in deciding if a suspicious host was infected, providing useful evidence that led to a positive diagnosis in 54.5% of the cases. Reconnaissance and vulnerability reports were useful in fewer cases, but helped diagnose more sophisticated malware, whereas blacklists were useful only for 10.5% of the incidents. In addition, we report which combinations ofsources helped diagnose different types ofmalware. Third, we make available a list of 165 Snort signatures that were effective in detecting validated malware without producing false positives. We analyze the differences between good and regular Snort signatures and observe that good signatures tend to use offsets, regular expressions, fixed packet sizes, and specific destination ports much more often than regular signatures. This shows that unlike common best practices for keeping IDS signatures simple, complexity in the case of signature writing is a virtue. In addition, we find that different signature features exhibit strong correlations with the effectiveness of a good signature, i.e., the number of validated incidents it detected. Based on this, we introduce a novel signature quality metric that can be used by security specialists to evaluate the available rulesets, prioritize the generated alerts, and facilitate the forensics analysis processes. Finally, we apply ourmetric to the most popular signature rulesets, i.e., to the Vulnerability Research Team, the Emerging Threats [1], the Bleeding Edge [2], and the SRI Bothunter [3] rulesets, and highlight their differences.
การแปล กรุณารอสักครู่..
