A critical vulnerability in Microsoft Internet Explorer outlined in Microsoft Security Bulletin MS08-078, is covered by a previously released rule. The rule to detect attacks targeting this vulnerability was included in the release on 2008-12-11 and is identified with GID 1, SID 15126. Future revisions of this rule will contain the appropriate reference information. Details on the rules from the release are here http://www.snort.org/vrt/advisories/Vrt-rules-2008-12,11.”]
Source: https://blog.talosintelligence.com/2008/12/snort-rule-coverage-for-ms08-078.html