Detection rules › Kusto
Cisco - firewall block but success logon to Microsoft Entra ID
'Correlate IPs blocked by a Cisco firewall appliance with successful Microsoft Entra ID signins. Because the IP was blocked by the firewall, that same IP logging on successfully to Entra ID is potentially suspect and could indicate credential compromise for the user account.'
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Initial Access | T1078 Valid Accounts |
Rule body kusto
id: 157c0cfc-d76d-463b-8755-c781608cdc1a
name: Cisco - firewall block but success logon to Microsoft Entra ID
description: |
'Correlate IPs blocked by a Cisco firewall appliance with successful Microsoft Entra ID signins.
Because the IP was blocked by the firewall, that same IP logging on successfully to Entra ID is potentially suspect and could indicate credential compromise for the user account.'
severity: Medium
requiredDataConnectors:
- connectorId: CiscoASA
dataTypes:
- CommonSecurityLog
- connectorId: AzureActiveDirectory
dataTypes:
- SigninLogs
- connectorId: AzureActiveDirectory
dataTypes:
- AADNonInteractiveUserSignInLogs
queryFrequency: 1d
queryPeriod: 1d
triggerOperator: gt
triggerThreshold: 0
tactics:
- InitialAccess
relevantTechniques:
- T1078
query: |
let aadFunc = (tableName:string){
CommonSecurityLog
| where DeviceVendor =~ "Cisco"
| where DeviceAction =~ "denied"
| where ipv4_is_private(SourceIP) == false
| summarize count() by SourceIP
| join (
// Successful signins from IPs blocked by the firewall solution are suspect
// Include fully successful sign-ins, but also ones that failed only at MFA stage
// as that supposes the password was sucessfully guessed.
table(tableName)
| where ResultType in ("0", "50074", "50076")
) on $left.SourceIP == $right.IPAddress
| extend AccountName = tostring(split(Account, "@")[0]), AccountUPNSuffix = tostring(split(Account, "@")[1])
};
let aadSignin = aadFunc("SigninLogs");
let aadNonInt = aadFunc("AADNonInteractiveUserSignInLogs");
union isfuzzy=true aadSignin, aadNonInt
entityMappings:
- entityType: Account
fieldMappings:
- identifier: FullName
columnName: UserPrincipalName
- identifier: Name
columnName: AccountName
- identifier: UPNSuffix
columnName: AccountUPNSuffix
- entityType: IP
fieldMappings:
- identifier: Address
columnName: SourceIP
version: 1.0.6
kind: Scheduled
metadata:
source:
kind: Community
author:
name: Microsoft Security Resarch
support:
tier: Community
categories:
domains: [ "Security - Network" ]
Stages and Predicates
Parameters
let aadSignin = aadFunc("SigninLogs");
let aadNonInt = aadFunc("AADNonInteractiveUserSignInLogs");
Let binding: aadFunc
let aadFunc = (tableName:string){
CommonSecurityLog
| where DeviceVendor =~ "Cisco"
| where DeviceAction =~ "denied"
| where ipv4_is_private(SourceIP) == false
| summarize count() by SourceIP
| join (
table(tableName)
| where ResultType in ("0", "50074", "50076")
) on $left.SourceIP == $right.IPAddress
| extend AccountName = tostring(split(Account, "@")[0]), AccountUPNSuffix = tostring(split(Account, "@")[1])
};
union isfuzzy=true (2 sources)
Each leg below queries one source; the rule matches if any leg does. Sources: aadSignin, aadNonInt