Failed AzureAD logons but success logon to host
Description
'Identifies a list of IP addresses with a minimum number (default of 5) of failed logon attempts to Microsoft Entra ID. Uses that list to identify any successful remote logons to hosts from these IPs within the same timeframe.'
Query · kql
//Adjust this threshold to fit the environment
let signin_threshold = 5;
//Make a list of all IPs with failed signins to AAD above our threshold
let aadFunc = (tableName:string){
let suspicious_signins =
table(tableName)
| where ResultType !in ("0", "50125", "50140")
| where IPAddress !in ('127.0.0.1', '::1', '')
| summarize count() by IPAddress
| where count_ > signin_threshold
| summarize make_set(IPAddress);
//See if any of these IPs have sucessfully logged into *nix hosts
let linux_logons =
Syslog
| where Facility contains "auth" and ProcessName != "sudo"
| where SyslogMessage has "Accepted"
| extend SourceIP = extract("(([0-9]{1,3})\\.([0-9]{1,3})\\.([0-9]{1,3})\\.(([0-9]{1,3})))",1,SyslogMessage)
| where SourceIP in (suspicious_signins)
| extend Reason = "Multiple failed AAD logins from IP address"
| project TimeGenerated, Computer, HostIP, IpAddress = SourceIP, SyslogMessage, Facility, ProcessName, Reason;
//See if any of these IPs have sucessfully logged into Windows hosts
let win_logons = (union isfuzzy=true
(SecurityEvent
| where EventID == 4624
| where LogonType in (10, 7, 3)
| where IpAddress != "-"
| where IpAddress in (suspicious_signins)
| extend Reason = "Multiple failed AAD logins from IP address"
| project TimeGenerated, Account, AccountType, Computer, Activity, EventID, LogonProcessName, IpAddress, LogonTypeName, TargetUserSid, TargetUserName, TargetDomainName, _ResourceId, Reason
),
(WindowsEvent
| where EventID == 4624 and has_any_ipv4(EventData, toscalar(suspicious_signins))
| extend LogonType = tostring(EventData.LogonType)
| where LogonType in (10, 7, 3)
| extend IpAddress = tostring(EventData.IpAddress)
| where IpAddress != "-"
| where IpAddress in (suspicious_signins)
| extend Reason = "Multiple failed AAD logins from IP address"
| extend Activity = "4624 - An account was successfully logged on."
| extend TargetUserName = tostring(EventData.TargetUserName), TargetDomainName = tostring(EventData.TargetDomainName)
| extend Account = strcat(TargetDomainName,"\\", TargetUserName)
| extend TargetUserSid = tostring(EventData.TargetUserSid)
| extend TargetAccount = strcat(EventData.TargetDomainName,"\\", EventData.TargetUserName)
| extend AccountType =case(Account endswith "$" or TargetUserSid in ("S-1-5-18", "S-1-5-19", "S-1-5-20"), "Machine", isempty(TargetUserSid), "", "User")
| extend LogonProcessName = tostring(EventData.LogonProcessName)
| project TimeGenerated, Account, AccountType, Computer, Activity, EventID, LogonProcessName, IpAddress, TargetUserSid, TargetUserName, TargetDomainName, _ResourceId, Reason
)
);
union isfuzzy=true linux_logons,win_logons
| extend timestamp = TimeGenerated
| extend HostName = tostring(split(Computer, ".")[0]), DomainIndex = toint(indexof(Computer, '.'))
| extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex+1), Computer)
};
let aadSignin = aadFunc("SigninLogs");
let aadNonInt = aadFunc("AADNonInteractiveUserSignInLogs");
union isfuzzy=true aadSignin, aadNonInt