Disable or Modify System Firewall T1686
Tactic: Defense Impairment
Adversaries may disable or modify host-based or network firewalls to impair defensive mechanisms and enable further action. Once an adversary has gathered sufficient privileges, they can tamper with firewall services, policies, or rule sets to remove restrictions on inbound or outbound traffic. For example, this may include turning off firewall profiles, altering existing rules to permit previously blocked ports or protocols, or adding new rules that create covert communication paths (e.g., adding a new firewall rule for a well-known protocol (such as RDP) using a non-traditional and potentially less securitized port.
Events covered
27 catalog events are tagged with this technique by at least one rule.
Authoring guide
Patterns shared across the 50 rules above: which fields they filter on, what specific values they look for, and what they exclude. The catalog normalizes field names across vendors so Sigma's Image, Elastic's process.name, and Splunk's process_name collapse into one row. Each rule contributes at most once per row.
Fields filtered most (36 distinct)
The fields most rules look at when detecting this technique. The How column shows the operators authors use (eq, wildcard, regex_match, match) and how often each appears. Sample values are concrete examples to start from, not an exhaustive list.
Top indicator values (231 distinct)
Specific (field, operator, value) combinations the rules check for, ranked by how many rules under this technique use each one. The Corpus reach column counts how many rules across the entire catalog (any technique) check the same combination. High numbers point to widely-used indicators that are likely noisy on their own; combine them with another condition for useful signal. Blank means the combination is specific to rules under this technique. Click a value to expand the rules under this technique that use it.
Exclusions (46 distinct)
Field/operator/value combinations excluded by rules under this technique (top-level not() clauses), sorted by how many rules exclude each. These are the false-positive paths the community has learned to filter out. A new rule that ignores the high-count entries here will likely fire on the same noisy paths. Click a value to expand the rules under this technique that exclude it.
Rules under this technique
Every rule in the catalog tagged with this technique, grouped by vendor. Click a rule title for its full predicates, exclusions, and indicators.
Sigma 32 rules
- A Rule Has Been Deleted From The Windows Firewall Exception List
- All Rules Have Been Deleted From The Windows Firewall Configuration
- Azure Firewall Modified or Deleted
- Azure Firewall Rule Collection Modified or Deleted
- Azure Network Firewall Policy Modified or Deleted
- Bpfdoor TCP Ports Redirect
- Disable Microsoft Defender Firewall via Registry
- Disable System Firewall
- Disable Windows Firewall by Registry
- Disabling Security Tools
- Disabling Security Tools - Builtin
- Firewall Disabled via Netsh.EXE
- Firewall Rule Deleted Via Netsh.EXE
- Firewall Rule Modified In The Windows Firewall Exception List
- Flush Iptables Ufw Chain
- Modify System Firewall
- Netsh Allow Group Policy on Microsoft Defender Firewall
- New Firewall Rule Added In Windows Firewall Exception List For Potential Suspicious Application
- New Firewall Rule Added In Windows Firewall Exception List Via WmiPrvSE.EXE
- New Firewall Rule Added Via Netsh.EXE
- New Network ACL Entry Added
- New Network Route Added
- New Windows Firewall Rule Added Via New-NetFirewallRule Cmdlet
- New Windows Firewall Rule Added Via New-NetFirewallRule Cmdlet - ScriptBlock
- RDP Connection Allowed Via Netsh.EXE
- Suspicious Program Location Whitelisted In Firewall Via Netsh.EXE
- The Windows Defender Firewall Service Failed To Load Group Policy
- UFW Disable Attempt
- Uncommon New Firewall Rule Added In Windows Firewall Exception List
- Windows Defender Firewall Has Been Reset To Its Default Configuration
- Windows Firewall Profile Disabled
- Windows Firewall Settings Have Been Changed
Splunk 18 rules
- Allow File And Printing Sharing In Firewall
- Allow Network Discovery In Firewall
- ASL AWS Network Access Control List Created with All Open Ports
- ASL AWS Network Access Control List Deleted
- AWS Network Access Control List Created with All Open Ports
- AWS Network Access Control List Deleted
- ESXi Firewall Disabled
- Firewall Allowed Program Enable
- Linux Auditd Disable Or Modify System Firewall
- Linux Iptables Firewall Modification
- Linux Stdout Redirection To Dev Null File
- Microsoft Intune DeviceManagementConfigurationPolicies
- O365 Bypass MFA via Trusted IP
- Windows Delete or Modify System Firewall
- Windows Firewall Rule Added
- Windows Firewall Rule Deletion
- Windows Firewall Rule Modification
- Windows Modify System Firewall with Notable Process Path