Windows: External Disk Drive or USB Storage Device

Rule ID

PH_Rule_SIGMA_249

Default Status

Enabled

Description

Detects external diskdrives or plugged in USB devices , EventID 6416 on windows 10 or later. This rule is adapted from https://github.com/SigmaHQ/sigma/blob/master/rules/windows/builtin/security/win_security_external_device.yml

Severity

MITRE ATT&CK® Tactics

Initial Access

Initial Access consists of techniques that use various entry vectors to gain their initial foothold within a network. Techniques used to gain a foothold include targeted spearphishing and exploiting weaknesses on public-facing web servers. Footholds gained through initial access may allow for continued access, like valid accounts and use of external remote services, or may be limited-use due to changing passwords.

https://attack.mitre.org/tactics/TA0001

MITRE ATT&CK® Techniques

T1091

Replication Through Removable Media

Adversaries may move onto systems, possibly those on disconnected or air-gapped networks, by copying malware to removable media and taking advantage of Autorun features when the media is inserted into a system and executes. In the case of Lateral Movement, this may occur through modification of executable files stored on removable media or by copying malware and renaming it to look like a legitimate file to trick users into executing it on a separate system. In the case of Initial Access, this may occur through manual manipulation of the media, modification of systems used to initially format the media, or modification to the media's firmware itself.

https://attack.mitre.org/techniques/T1091

T1200

Hardware Additions

Adversaries may introduce computer accessories, computers, or networking hardware into a system or network that can be used as a vector to gain access. Many penetration testers leverage hardware additions for initial access. Commercial and open source products are leveraged with capabilities such as passive network tapping, man-in-the middle encryption breaking, keystroke injection, kernel memory reading via DMA, adding new wireless access to an existing network, and others.

https://attack.mitre.org/techniques/T1200

Impacts

Server

Data Source

Windows Security Log via OMI or FortiSIEM Agent

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.

Filter

SubPattern Definitions

SubPattern Name: Filter

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="Win-Security-6416" AND deviceType="DiskDrive") OR description="USB Mass Storage Device"

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

hostName,description,deviceType

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

 hostName = Filter.hostName,
 description = Filter.description,
deviceType = Filter.deviceType

FortiSIEM Rules