T1686: Disable or Modify System Firewall
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.
Adversaries may disable or modify firewalls using different behaviors, depending on the platform. For example, in ESXi, firewall rules may be modified directly via the esxcli (e.g., via esxcli network firewall set) or via the vCenter user interface.
How it's found
Detection of Disabled or Modified System Firewalls across OS Platforms.: Detection of firewall tampering by monitoring processes executing netsh, PowerShell Set-NetFirewallProfile, or sc stop mpssvc. Registry modifications under HKLM\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy also indicate adversarial actions. Detection of iptables, nftables, or firewalld rule modifications. Correlation of sudden drops in active firewall rules with suspicious processes suggests adversarial evasion. Detection of PF firewall rule modifications via pfctl, socketfilterfw, or defaults write to com.apple.alf. Adversaries often disable firewall profiles entirely or whitelist malicious processes. Detection of firewall changes using esxcli network firewall set or vSphere API modifications. Sudden disabling of firewall rules across management interfaces is a strong adversarial signal. Detection of firewall ACL or rule base changes through CLI (e.g., no access-list, permit any any). Monitor configuration commits from unusual users or sessions.
Sub-techniques
T1686.001: Cloud Firewall
Adversaries may disable or modify a firewall within a cloud environment to bypass controls that limit access to cloud resources. Cloud environments typically utilize restrictive security groups and firewall rules that only allow network activity from trusted IP addresses via expected ports and protocols. An adversary with appropriate permissions may introduce new firewall rules or policies to allow access into a victim cloud environment and/or move laterally from the cloud control plane to the data plane. For example, an adversary may use a script or utility that creates new ingress rules in existing security groups (or creates new security groups entirely) to allow any TCP/IP connectivity to a cloud-hosted instance. They may also remove networking limitations to support traffic associated with malicious activity (such as cryptomining).
T1686.002: Network Device Firewall
Adversaries may disable network device-based firewall mechanisms entirely or add, delete, or modify particular rules in order to bypass controls limiting network usage. Adversaries may obtain access to devices such as routers, switches, or other perimeter/network devices and change access control lists (ACLs), security zones, or policy rules to permit otherwise blocked traffic. For example, adversaries may add new network firewall rules to allow access to all internal network subnets without restrictions. Allowing access to internal network subsets may enable unrestricted inbound/outbound connectivity or open paths for command and control and lateral movement. Adversaries may obtain access to network device management interfaces via Valid Accounts or by exploiting vulnerabilities. In some cases, threat actors may target firewalls and other network infrastructure that are exposed to the internet by leveraging weaknesses in public-facing applications (Exploit Public-Facing Application). Adversaries may also modify host networking configurations that indirectly manipulate system firewalls, such as adjusting interface bandwidth or network connection request thresholds.
T1686.003: Windows Host Firewall
Adversaries may disable or modify the Windows host firewall to bypass controls limiting network usage. This can include disabling the Windows host firewall entirely, suppressing specific profiles (domain, private, public), or adding, deleting, and modifying firewall rules to allow or restrict traffic. Adversaries may perform these modifications through multiple mechanisms depending on the Windows operating system and access level. For example, adversaries may use command-line utilities (e.g., `netsh advfirewall` or PowerShell cmdlets like `Set-NetFirewallProfile`, `New-NetFirewallRule`), Windows Registry modifications (e.g., altering firewall states and rule configurations via registry keys), or the Windows Control Panel to modify firewall settings through the Windows Security interface. By disabling or modifying Windows firewall services, adversaries may enable access to remote services, open ports for command and control traffic, or configure rules for further actions.
Standards mapping
Where this fits in a TurboPentest engagement
This weakness is not covered by the automated black-box pentest. IntegSec pentesters cover it in a manual engagement.
Frequently asked questions
What is T1686 Disable or Modify System Firewall?
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. Adversaries may disable or modify firewalls using different behaviors, depending on the platform. For example, in ESXi, firewall rules may be modified directly via the esxcli (e.g., via esxcli network firewall set) or via the vCenter user interface.
Which tactics does T1686 belong to?
T1686 maps to the Defense Impairment tactic.
Does TurboPentest test for Disable or Modify System Firewall?
This weakness is not covered by the automated black-box pentest. IntegSec pentesters cover it in a manual engagement.
Related MITRE ATT&CK techniques
- Persistence, Defense ImpairmentT1112: Modify Registry
- Defense ImpairmentT1207: Rogue Domain Controller
- Defense ImpairmentT1222: File and Directory Permissions Modification
- Privilege Escalation, Defense ImpairmentT1484: Domain or Tenant Policy Modification
- Defense ImpairmentT1553: Subvert Trust Controls
- Persistence, Defense Impairment, Credential AccessT1556: Modify Authentication Process
About this reference
These security references are maintained by IntegSec, an offensive-security firm whose team holds CISSP, OSCP, and OSCE certifications and has run thousands of penetration tests. Content is kept current as tools, standards, and attack techniques evolve.
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