/* This Yara ruleset is under the GNU-GPLv2 license (http://www.gnu.org/licenses/gpl-2.0.html) and open to any user or organization, as long as you use it under this license. */ rule with_attachment : mail { meta: author = "Antonio Sanchez <asanchez@hispasec.com>" reference = "http://laboratorio.blogs.hispasec.com/" description = "Rule to detect the presence of an or several attachments" strings: $attachment_id = "X-Attachment-Id" condition: $attachment_id } rule without_attachments : mail { meta: author = "Antonio Sanchez <asanchez@hispasec.com>" reference = "http://laboratorio.blogs.hispasec.com/" description = "Rule to detect the no presence of any attachment" strings: $attachment_id = "X-Attachment-Id" condition: not $attachment_id }