SSH - Potential Brute Force

Requête originale, sans modification.

let threshold = 15;
Syslog
| where ProcessName =~ "sshd"
| where SyslogMessage contains "Failed password for invalid user"
| parse kind=relaxed SyslogMessage with * "invalid user " user " from " ip " port" port " ssh2" *
// using distinct below as it has been seen that Syslog can duplicate entries depending on implementation
| distinct TimeGenerated, Computer, user, ip, port, SyslogMessage, _ResourceId
| summarize EventTimes = make_list(TimeGenerated), PerHourCount = count() by bin(TimeGenerated,4h), ip, Computer, user, _ResourceId
| where PerHourCount > threshold
| mvexpand EventTimes
| extend EventTimes = tostring(EventTimes)
| summarize StartTime = min(EventTimes), EndTime = max(EventTimes), UserList = make_set(user), ComputerList = make_set(Computer), ResourceIdList = make_set(_ResourceId), sum(PerHourCount) by IPAddress = ip
// bringing through single computer and user if array only has 1, otherwise, referencing the column and hashing the ComputerList or UserList so we don't get accidental entity matches when reviewing alerts
| extend HostName = iff(array_length(ComputerList) == 1, tostring(ComputerList[0]), strcat("SeeComputerListField","_", tostring(hash(tostring(ComputerList)))))
| extend Account = iff(array_length(ComputerList) == 1, tostring(UserList[0]), strcat("SeeUserListField","_", tostring(hash(tostring(UserList)))))
| extend ResourceId = iff(array_length(ResourceIdList) == 1, tostring(ResourceIdList[0]), strcat("SeeResourceIdListField","_", tostring(hash(tostring(ResourceIdList)))))