Spam/Malicious Mail Attachment found but not remediated

Rule ID

PH_Rule_Vuln_3

Default Status

Enabled

Description

Detects that host anti-virus or content inspection devices found a Spam/Malicious Mail Attachment but could not remediate it. The sender is sending to 5 or more distinct receiver mail addresses

Severity

MITRE ATT&CK® Tactics

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/TA0009

MITRE ATT&CK® Techniques

T1114.001

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/T1114/001

Impacts

Server

Data Source

FortiGate via Syslog, FortiProxy via Syslog, FortiMail via Syslog

Detection

Correlation

Remediation Guidance

No remediation guidance specified

Time Window

If the following pattern or patterns match an ingested event within the given time window in seconds, trigger an incident.

300 seconds

Trigger Conditions

If the following defined pattern/s occur within a 300 second time window.

AttachFound

SubPattern Definitions

SubPattern Name: AttachFound

This is the named definition of the event query, this is important if multiple subpatterns are defined to distinguish them.

SubPattern Query

This is the query logic that matches incoming events

eventType IN (Group@PH_SYS_EVENT_MailMalware_Found)

Group by Attributes

This defines how matching events are aggregated, only events with the same matching attribute values are grouped into one unique incident ID

hostIpAddr,senderMailAddr,mailSubject

Aggregate Constraint

This is most typically a numerical constraint that defines when the rule should trigger an incident

COUNT(DISTINCT receiverMailAddr) >= 5

Incident Attribute Mapping

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 = AttachFound.hostIpAddr,
 senderMailAddr = AttachFound.senderMailAddr,
 mailSubject = AttachFound.mailSubject

FortiSIEM Rules