Mimecast: User clicked malicious link in email

Rule ID

PH_RULE_MIMECAST_MaliciousURLClick

Default Status

Enabled

Description

This rule is generated when a user clicks a url that Mimecast sandbox has determined it to be malicious. The underlying event is clickLogs whenever a user clicks a url that Mimecast has rewritten in an email.

Severity

Detection Technology

Correlation

Rule Mode

Streaming

MITRE ATT&CK® Tactics

Reconnaissance

Reconnaissance consists of techniques that involve adversaries actively or passively gathering information that can be used to support targeting. Such information may include details of the victim organization, infrastructure, or staff/personnel. This information can be leveraged by the adversary to aid in other phases of the adversary lifecycle, such as using gathered information to plan and execute Initial Access, to scope and prioritize post-compromise objectives, or to drive and lead further Reconnaissance efforts.

https://attack.mitre.org/tactics/TA0043

MITRE ATT&CK® Techniques

T1598.003

Phishing for Information: Spearphishing Link

Before compromising a victim, adversaries may send spearphishing messages with a malicious link to elicit sensitive information that can be used during targeting. Spearphishing for information is an attempt to trick targets into divulging information, frequently credentials or other actionable information. Spearphishing for information frequently involves social engineering techniques, such as posing as a source with a reason to collect information (ex: Establish Accounts or Compromise Accounts and/or sending multiple, seemingly urgent messages.

https://attack.mitre.org/techniques/T1598/003

Impacts

Application

Data Source

Mimecast via MIMECAST_API

Detection

Correlation

Remediation Guidance

Investigate and determine if the email sender and the URL provided in the email was legitimate.

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.

url_click

SubPattern Definitions

SubPattern Name: url_click

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 ("Mimecast_clickLogs_warn","Mimecast_clickLogs_allow","Mimecast_clickLogs_unknown","Mimecast_clickLogs_wait") AND scanStatus="malicious"

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

infoURL,scanStatus,action,mailSubject,receiverMailAddr,senderMailAddr

Aggregate Constraint

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

COUNT(*) >= 1

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

receiverMailAddr = url_click.receiverMailAddr,
senderMailAddr = url_click.senderMailAddr,
mailSubject = url_click.mailSubject,
action = url_click.action,
scanStatus = url_click.scanStatus,
infoURL = url_click.infoURL

FortiSIEM Rules