Name:Mailsniper Invoke functions id:a36972c8-b894-11eb-9f78-acde48001122 version:4 date:2024-09-30 author:Teoderick Contreras, Splunk status:production type:TTP Description:The following analytic detects the execution of known MailSniper PowerShell functions on a machine. It leverages PowerShell logs (EventCode 4104) to identify specific script block text associated with MailSniper activities. This behavior is significant as MailSniper is often used by attackers to harvest sensitive emails from compromised Exchange servers. If confirmed malicious, this activity could lead to unauthorized access to sensitive email data, credential theft, and further compromise of the email infrastructure. Data_source:
-Powershell Script Block Logging 4104
search:`powershell` EventCode=4104 ScriptBlockText IN ("*Invoke-GlobalO365MailSearch*", "*Invoke-GlobalMailSearch*", "*Invoke-SelfSearch*", "*Invoke-PasswordSprayOWA*", "*Invoke-PasswordSprayEWS*","*Invoke-DomainHarvestOWA*", "*Invoke-UsernameHarvestOWA*","*Invoke-OpenInboxFinder*","*Invoke-InjectGEventAPI*","*Invoke-InjectGEvent*","*Invoke-SearchGmail*", "*Invoke-MonitorCredSniper*", "*Invoke-AddGmailRule*","*Invoke-PasswordSprayEAS*","*Invoke-UsernameHarvestEAS*") | stats count min(_time) as firstTime max(_time) as lastTime by Opcode Computer UserID EventCode ScriptBlockText | rename Computer as dest | rename UserID as user | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `mailsniper_invoke_functions_filter`
how_to_implement:To successfully implement this search, you need to be ingesting logs with the powershell logs from your endpoints. make sure you enable needed registry to monitor this event. known_false_positives:unknown References: -https://www.blackhillsinfosec.com/introducing-mailsniper-a-tool-for-searching-every-users-email-for-sensitive-data/ drilldown_searches: name:'View the detection results for - "$dest$" and "$user$"' search:'%original_detection_search% | search dest = "$dest$" user = "$user$"' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' name:'View risk events for the last 7 days for - "$dest$" and "$user$"' search:'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$", "$user$") 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: - 'Data Exfiltration' asset_type:Endpoint confidence:80 impact:90 message:Potential mailsniper.ps1 functions executed on dest $dest$ by user $user$. mitre_attack_id: - 'T1114' - 'T1114.001' observable: name:'dest' type:'Endpoint' - role: - 'Victim' name:'user' type:'User' - role: - 'Victim' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - '_time' - 'ScriptBlockText' - 'Opcode' - 'Computer' - 'UserID' - 'EventCode' risk_score:72 security_domain:endpoint
