Elastic medium deprecated eql

Suspicious File Changes Activity Detected

This rule identifies a sequence of 100 file extension rename events within a set of common file paths by the same process in a timespan of 1 second. Ransomware is a type of malware that encrypts a victim's files or systems and demands payment (usually in cryptocurrency) in exchange for the decryption key. One important indicator of a ransomware attack is the mass encryption of the file system, after which a new file extension is added to the file.

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Detection Logic

sequence by process.entity_id, host.id with maxspan=1s
  [file where host.os.type == "linux" and event.type == "change" and event.action == "rename" and file.extension : "?*" 
   and process.executable : ("./*", "/tmp/*", "/var/tmp/*", "/dev/shm/*", "/var/run/*", "/boot/*", "/srv/*", "/run/*") and
   file.path : (
     "/home/*/Downloads/*", "/home/*/Documents/*", "/root/*", "/bin/*", "/usr/bin/*", "/var/log/*", "/var/lib/log/*",
     "/var/backup/*", "/var/www/*"
   ) and
   not process.name : (
     "dpkg", "yum", "dnf", "rpm", "dockerd", "go", "java", "pip*", "python*", "node", "containerd", "php", "p4d",
     "conda", "chrome", "imap", "cmake", "firefox", "semanage", "semodule", "ansible-galaxy", "fc-cache", "jammy", "git",
     "systemsettings", "vmis-launcher", "bundle", "kudu-tserver", "suldownloader"
    )
   ] with runs=25

Field Validations

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