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.[1]
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.[2][3]
| ID | Name | Description |
|---|---|---|
| G0082 | APT38 |
APT38 have created firewall exemptions on specific ports, including ports 443, 6443, 8443, and 9443.[4] |
| S0031 | BACKSPACE |
The "ZR" variant of BACKSPACE will check to see if known host-based firewalls are installed on the infected systems. BACKSPACE will attempt to establish a C2 channel, then will examine open windows to identify a pop-up from the firewall software and will simulate a mouse-click to allow the connection to proceed.[5] |
| G1043 | BlackByte |
BlackByte modified firewall rules on victim machines to enable remote system discovery.[6][7] |
| S1161 | BPFDoor |
BPFDoor starts a shell on a high TCP port starting at 42391 up to 43391, then changes the local |
| G0008 | Carbanak |
Carbanak may use netsh to add local firewall rule exceptions.[9] |
| S0492 | CookieMiner |
CookieMiner has checked for the presence of "Little Snitch", macOS network monitoring and application firewall software, stopping and exiting if it is found.[10] |
| G0035 | Dragonfly |
Dragonfly has disabled host-based firewalls. The group has also globally opened port 3389.[11] |
| G0046 | FIN7 |
FIN7 has added a firewall rule to allow TCP port 59999 inbound and a rule to allow sshd.exe on TCP port 9898.[12] |
| S0531 | Grandoreiro |
Grandoreiro can block the Deibold Warsaw GAS Tecnologia security tool at the firewall level.[13] |
| S1211 | Hannotog |
Hannotog can modify local firewall settings via |
| S0376 | HOPLIGHT | |
| S0260 | InvisiMole |
InvisiMole has a command to disable routing and the Firewall on the victim’s machine.[16] |
| S0088 | Kasidet |
Kasidet has the ability to change firewall settings to allow a plug-in to be downloaded.[17] |
| G0094 | Kimsuky |
Kimsuky has been observed disabling the system firewall.[18] |
| C0049 | Leviathan Australian Intrusions |
Leviathan modified system firewalls to add two open listening ports on 9998 and 9999 during Leviathan Australian Intrusions.[19] |
| G1051 | Medusa Group |
Medusa Group has utilized PsExec to execute batch scripts that modify firewall settings.[20] Medusa Group has also enabled and modified firewall rules to allow for RDP connections for lateral movement and device interactions.[20] |
| S0336 | NanoCore | |
| S0108 | netsh |
netsh can be used to disable local firewall settings.[23][24] |
| S0013 | PlugX |
PlugX has modified local firewall rules on victim machines to enable a random, high-number listening port for subsequent access and C2 activity.[25] |
| S1032 | PyDCrypt |
PyDCrypt has modified firewall rules to allow incoming SMB, NetBIOS, and RPC connections using |
| G0106 | Rocke |
Rocke used scripts which killed processes and added firewall rules to block traffic related to other cryptominers.[27] |
| G1045 | Salt Typhoon |
Salt Typhoon has made changes to the Access Control List (ACL) and loopback interface address on compromised devices.[28] |
| S1178 | ShrinkLocker |
ShrinkLocker turns on the system firewall and deletes all of its rules during execution.[29][30] |
| C0024 | SolarWinds Compromise |
During the SolarWinds Compromise, APT29 used |
| G0139 | TeamTNT | |
| S1223 | THINCRUST |
THINCRUST can use the Django python module "django.views.decorators.csrf" along with the decorator "csrf_exempt" within victim firewalls to disable cross-site request forgery protections.[33] |
| G1022 | ToddyCat |
Prior to executing a backdoor ToddyCat has run |
| G1048 | UNC3886 |
UNC3886 has used the TABLEFLIP traffic redirection utility and the esxcli command line to modify firewall rules.[35][36][33] |
| G1047 | Velvet Ant |
Velvet Ant modified system firewall settings during PlugX installation using |
| S0412 | ZxShell |
ZxShell can disable the firewall by modifying the registry key |
| ID | Mitigation | Description |
|---|---|---|
| M1047 | Audit |
Routinely check account role permissions to ensure only expected users and roles have permission to modify system firewalls. |
| M1022 | Restrict File and Directory Permissions |
Ensure proper process and file permissions are in place to prevent adversaries from disabling or modifying firewall settings. |
| M1024 | Restrict Registry Permissions |
Ensure proper Registry permissions are in place to prevent adversaries from disabling or modifying firewall settings. |
| M1018 | User Account Management |
Ensure proper user permissions are in place to prevent adversaries from disabling or modifying firewall settings. |
| ID | Name | Analytic ID | Analytic Description |
|---|---|---|---|
| DET0145 | Detection of Disabled or Modified System Firewalls across OS Platforms. | AN0406 |
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. |
| AN0407 |
Detection of iptables, nftables, or firewalld rule modifications. Correlation of sudden drops in active firewall rules with suspicious processes suggests adversarial evasion. |
||
| AN0408 |
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. |
||
| AN0409 |
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. |
||
| AN0410 |
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. |