Detection rules › Sigma
Dfsvc.EXE Initiated Network Connection Over Uncommon Port
Detects an initiated network connection over uncommon ports from "dfsvc.exe". A utility used to handled ClickOnce applications.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Execution | T1203 Exploitation for Client Execution |
Event coverage
| Provider | Event | Title |
|---|---|---|
| Sysmon | Event ID 3 | Network connection |
Rule body yaml
title: Dfsvc.EXE Initiated Network Connection Over Uncommon Port
id: 4c5fba4a-9ef6-4f16-823d-606246054741
status: test
description: Detects an initiated network connection over uncommon ports from "dfsvc.exe". A utility used to handled ClickOnce applications.
references:
- https://posts.specterops.io/less-smartscreen-more-caffeine-ab-using-clickonce-for-trusted-code-execution-1446ea8051c5
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-06-12
modified: 2024-01-31
tags:
- attack.execution
- attack.t1203
- detection.threat-hunting
logsource:
category: network_connection
product: windows
detection:
selection:
Image|contains: ':\Windows\Microsoft.NET\'
Image|endswith: '\dfsvc.exe'
Initiated: 'true'
filter_main_known_ports:
DestinationPort:
- 80
- 443
filter_optional_dns_ipv6:
# Based on VT. More than 140 binaries made communication over DNS
DestinationIsIpv6: 'true'
DestinationPort: 53
condition: selection and not 1 of filter_main_* and not 1 of filter_optional_*
falsepositives:
- Unknown
level: high
Stages and Predicates
Stage 0: condition
selection and not 1 of filter_main_* and not 1 of filter_optional_*Stage 1: selection
selection:
Image|contains: ':\Windows\Microsoft.NET\'
Image|endswith: '\dfsvc.exe'
Initiated: 'true'
Stage 2: not filter_main_known_ports
filter_main_known_ports:
DestinationPort:
- 80
- 443
Stage 3: not filter_optional_dns_ipv6
filter_optional_dns_ipv6:
DestinationIsIpv6: 'true'
DestinationPort: 53
Exclusions
Top-level NOT(...) conjuncts: predicates this rule actively suppresses.
| Field | Kind | Excluded values |
|---|---|---|
DestinationPort | eq | 443 |
DestinationPort | eq | 80 |
DestinationIsIpv6 | eq | true |
DestinationPort | eq | 53 |
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.