Name:Azure AD Multiple AppIDs and UserAgents Authentication Spike id:5d8bb1f0-f65a-4b4e-af2e-fcdb88276314 version:5 date:2024-09-30 author:Mauricio Velazco, Splunk status:production type:Anomaly Description:The following analytic detects unusual authentication activity in Azure AD, specifically when a single user account has over 8 authentication attempts using 3+ unique application IDs and 5+ unique user agents within a short period. It leverages Azure AD audit logs, focusing on authentication events and using statistical thresholds. This behavior is significant as it may indicate an adversary probing for MFA requirements. If confirmed malicious, it suggests a compromised account, potentially leading to further exploitation, lateral movement, and data exfiltration. Early detection is crucial to prevent substantial harm. Data_source:
-Azure Active Directory Sign-in activity
search:`azure_monitor_aad` category=SignInLogs operationName="Sign-in activity" (properties.authenticationRequirement="multiFactorAuthentication" AND properties.status.additionalDetails="MFA required in Azure AD") OR (properties.authenticationRequirement=singleFactorAuthentication AND "properties.authenticationDetails{}.succeeded"=true) | bucket span=5m _time | rename properties.* as * | stats count min(_time) as firstTime max(_time) as lastTime dc(appId) as unique_app_ids dc(userAgent) as unique_user_agents values(appDisplayName) values(deviceDetail.operatingSystem) by user, src_ip | where count > 5 and unique_app_ids > 2 and unique_user_agents > 5 | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `azure_ad_multiple_appids_and_useragents_authentication_spike_filter`
how_to_implement:You must install the latest version of Splunk Add-on for Microsoft Cloud Services from Splunkbase (https://splunkbase.splunk.com/app/3110/#/details). You must be ingesting Azure Active Directory events into your Splunk environment through an EventHub. This analytic was written to be used with the azure:monitor:aad sourcetype leveraging the SignInLogs log category. known_false_positives:Rapid authentication from the same user using more than 5 different user agents and 3 application IDs is highly unlikely under normal circumstances. However, there are potential scenarios that could lead to false positives. References: -https://attack.mitre.org/techniques/T1078/ -https://www.blackhillsinfosec.com/exploiting-mfa-inconsistencies-on-microsoft-services/ -https://github.com/dafthack/MFASweep -https://www.youtube.com/watch?v=SK1zgqaAZ2E drilldown_searches: name:'View the detection results for - "$user$"' search:'%original_detection_search% | search user = "$user$"' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' name:'View risk events for the last 7 days for - "$user$"' search:'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$user$") starthoursago=168 | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' tags: analytic_story: - 'Azure Active Directory Account Takeover' asset_type:Azure Tenant confidence:80 impact:60 message:$user$ authenticated in a short periof of time with more than 5 different user agents across 3 or more unique application ids. mitre_attack_id: - 'T1078' observable: name:'user' type:'User' - role: - 'Victim' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' risk_score:48 required_fields: - '_time' - 'category' - 'user' - 'src_ip' - 'operationName' - 'properties.authenticationRequirement' - 'properties.status.additionalDetails' - 'properties.authenticationDetails{}.succeeded' - 'properties.userAgent' - 'properties.appDisplayName' security_domain:identity
