PH_Rule_Flow_19
Enabled
Detects a scenario where a host, that is itself not an authorized mail gateway, is sending excessive emails (more than 20 emails in 2 minutes). This behavior may indicate malware running on an end host that is trying to send spam or privileged information to its own set of mail servers (which may be compromised).
8
Security
Collection
Collection consists of techniques adversaries may use to gather information and the sources information is collected from that are relevant to following through on the adversary's objectives. Frequently, the next goal after collecting data is to steal (exfiltrate) the data. Common target sources include various drive types, browsers, audio, video, and email. Common collection methods include capturing screenshots and keyboard input.
https://attack.mitre.org/tactics/TA0009T1114.001
Email Collection: Local Email Collection
Adversaries may sniff network traffic to capture information about an environment, including authentication material passed over the network. Network sniffing refers to using the network interface on a system to monitor or capture information sent over a wired or wireless connection. An adversary may place a network interface into promiscuous mode to passively access data in transit over the network, or use span ports to capture a larger amount of data.
https://attack.mitre.org/techniques/T1114/001Application
FortiGate via Syslog or Netflow, Checkpoint via Syslog or Netflow, Palo Alto via Syslog or Netflow
Correlation
No remediation guidance specified
If the following pattern or patterns match an ingested event within the given time window in seconds, trigger an incident.
120 seconds
If the following defined pattern/s occur within a 120 second time window.
EndUserExcessMail
This is the named definition of the event query, this is important if multiple subpatterns are defined to distinguish them.
This is the query logic that matches incoming events
ipProto = 6 AND destIpPort = 25 AND srcIpAddr NOT IN (Group@PH_SYS_DEVICE_SEC_GW,Group@PH_SYS_APP_MAIL_SERVER) AND srcIpAddr IN (Group@PH_SYS_NETWORK_ENTERPRISE_INTERNAL_NET) AND eventType IN (Group@PH_SYS_EVENT_PermitNetTraffic, Group@PH_SYS_EVENT_NetflowTraffic, Group@PH_SYS_EVENT_BiNetflowTraffic,Group@PH_SYS_EVENT_DenyNetTraffic)
This defines how matching events are aggregated, only events with the same matching attribute values are grouped into one unique incident ID
srcIpAddr
This is most typically a numerical constraint that defines when the rule should trigger an incident
COUNT(*) >= 20
This section defines which fields in matching raw events should be mapped to the incident attributes in the resulting incident.
The available raw event attributes to map are limited to the group by attributes and the aggregate event constraint fields for each subpattern
srcIpAddr = EndUserExcessMail.srcIpAddr,
incidentCount = EndUserExcessMail.COUNT(*)