FortiSIEM Rules

Windows: BITS Transfer Job With Uncommon Or Suspicious Remote TLD

Rule ID


Default Status



Detects a suspicious download using the BITS client from a FQDN that is unusual. Adversaries may abuse BITS jobs to persistently execute or clean up after malicious payloads. This rule is adapted from






Defense Evasion

Defense Evasion consists of techniques that adversaries use to avoid detection throughout their compromise. Techniques used for defense evasion include uninstalling/disabling security software or obfuscating/encrypting data and scripts. Adversaries also leverage and abuse trusted processes to hide and masquerade their malware. Other tactics’ techniques are cross-listed here when those techniques include the added benefit of subverting defenses.

MITRE ATT&CK® Techniques



Adversaries may abuse Windows Background Intelligent Transfer Service (BITS) jobs to persistently execute or clean up after malicious payloads. BITS is a low-bandwidth, asynchronous file transfer mechanism exposed through Component Object Model. BITS is commonly used by updaters, messengers, and other applications preferred to operate in the background. The interface to create and manage BITS jobs is accessible through PowerShell. Adversaries may abuse BITS to download, execute, and even clean up after running malicious code. BITS upload functionalities can also be used to perform Exfiltration Over Alternative Protocol.



Data Source

Windows BitsClient logs via FortiSIEM Agent



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.


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-App-Microsoft-Windows-Bits-Client-16403" AND ((targetName  NOT REGEXP ".*\.azureedge\.net/.*|.*\.com/.*|.*\.sfx\.ms/.*|.*download\.mozilla\.org/.*"))

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


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,
targetName = Filter.targetName