Large Inbound Transfer From Outside My Country

Rule ID

PH_Rule_Flow_212

Default Status

Enabled

Description

Detects a large inbound transfer (larger than 2MB in 10 minutes) from an external destination that is outside my country. The rule is written for United States and may need to be tuned for other countries.

Severity

MITRE ATT&CK® Tactics

Command And Control

MITRE ATT&CK® Techniques

T1071.001

Application Layer Protocol: Web Protocols

Adversaries may communicate by concealing their data inside application layer protocols associated with web traffic to avoid detection/network filtering by blending in with existing traffic. Commands to the remote system, and often the results of those commands, will be embedded within the protocol traffic between the client and server.

https://attack.mitre.org/techniques/T1071/001

Impacts

Network

Data Source

FortiGate via Syslog or Netflow,Checkpoint via Syslog or Netflow, Palo Alto via Syslog or Netflow

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.

600 seconds

Trigger Conditions

If the following defined pattern/s occur within a 600 second time window.

LargeXfer

SubPattern Definitions

SubPattern Name: LargeXfer

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

srcIpAddr NOT IN (Group@PH_SYS_NETWORK_ENTERPRISE_INTERNAL_NET) AND destIpAddr IN (Group@PH_SYS_NETWORK_ENTERPRISE_INTERNAL_NET) AND reptDevIpAddr IN (Group@PH_SYS_DEVICE_FIREWALL) AND eventType IN (Group@PH_SYS_EVENT_PermitNetTraffic, Group@PH_SYS_EVENT_NetflowTraffic, Group@PH_SYS_EVENT_BiNetflowTraffic) AND srcGeoCountry NOT IN (Group@PH_COUNTRY_GROUP_MYHOME)

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

srcIpAddr, destIpAddr

Aggregate Constraint

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

SUM(sentBytes64) >= 2097152

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 = LargeXfer.srcIpAddr,
 destIpAddr = LargeXfer.destIpAddr,
 sentBytes64 = LargeXfer.SUM(sentBytes64)

FortiSIEM Rules