Impair Defenses: Disable or Modify System Firewall

During APT28 Nearest Neighbor Campaign, APT28 added rules to a victim's Windows firewall to set up a series of port-forwards allowing traffic to target systems.^[5]

APT38 have created firewall exemptions on specific ports, including ports 443, 6443, 8443, and 9443.^[6]

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.^[7]

BADCALL disables the Windows firewall before binding to a port.^[8]

BlackByte modified firewall rules on victim machines to enable remote system discovery.^[9][10]

BlackByte 2.0 Ransomware modifies the Windows firewall during execution.^[11]

BPFDoor starts a shell on a high TCP port starting at 42391 up to 43391, then changes the local iptables rules to redirect all packets from the attacker to the shell port.^[12]

Carbanak may use netsh to add local firewall rule exceptions.^[13]

CookieMiner has checked for the presence of "Little Snitch", macOS network monitoring and application firewall software, stopping and exiting if it is found.^[14]

Cyclops Blink can modify the Linux iptables firewall to enable C2 communication on network devices via a stored list of port numbers.^[15][16]

DarkComet can disable Security Center functions like the Windows Firewall.^[17][18]

Dragonfly has disabled host-based firewalls. The group has also globally opened port 3389.^[19]

Grandoreiro can block the Deibold Warsaw GAS Tecnologia security tool at the firewall level.^[20]

H1N1 kills and disables services for Windows Firewall.^[21]

Hannotog can modify local firewall settings via netsh commands to open a listening UDP port.^[22]

HARDRAIN opens the Windows Firewall to modify incoming connections.^[23]

HOPLIGHT has modified the firewall using netsh.^[24]

InvisiMole has a command to disable routing and the Firewall on the victim’s machine.^[25]

Kasidet has the ability to change firewall settings to allow a plug-in to be downloaded.^[26]

Kimsuky has been observed disabling the system firewall.^[27]

Various Lazarus Group malware modifies the Windows firewall to allow incoming connections or disable it entirely using netsh. ^[28][29][30]

Leviathan modified system firewalls to add two open listening ports on 9998 and 9999 during Leviathan Australian Intrusions.^[31]

Magic Hound has added the following rule to a victim's Windows firewall to allow RDP traffic - "netsh" advfirewall firewall add rule name="Terminal Server" dir=in action=allow protocol=TCP localport=3389.^[32][33]

Moses Staff has used batch scripts that can disable the Windows firewall on specific remote machines.^[34]

NanoCore can modify the victim's firewall.^[35][36]

netsh can be used to disable local firewall settings.^[37][38]

njRAT has modified the Windows firewall to allow itself to communicate through the firewall.^[39][40]

OilRig has modified Windows firewall rules to enable remote access.^[41]

During Operation Wocao, threat actors used PowerShell to add and delete rules in the Windows firewall.^[42]

PlugX has modified local firewall rules on victim machines to enable a random, high-number listening port for subsequent access and C2 activity.^[43]

PyDCrypt has modified firewall rules to allow incoming SMB, NetBIOS, and RPC connections using netsh.exe on remote machines.^[34]

Remsec can add or remove applications or ports on the Windows firewall or disable it entirely.^[44]

Rocke used scripts which killed processes and added firewall rules to block traffic related to other cryptominers.^[45]

Salt Typhoon has made changes to the Access Control List (ACL) and loopback interface address on compromised devices.^[46]

ShrinkLocker turns on the system firewall and deletes all of its rules during execution.^[47][48]

During the SolarWinds Compromise, APT29 used netsh to configure firewall rules that limited certain UDP outbound packets.^[49]

TeamTNT has disabled iptables.^[50]

Prior to executing a backdoor ToddyCat has run cmd /c start /b netsh advfirewall firewall add rule name="SGAccessInboundRule" dir=in protocol=udp action=allow localport=49683 to allow the targeted system to receive UDP packets on port 49683.^[51]

TYPEFRAME can open the Windows Firewall on the victim’s machine to allow incoming connections.^[52]

Velvet Ant modified system firewall settings during PlugX installation using netsh.exe to open a listening, random high number port on victim devices.^[43]

ZxShell can disable the firewall by modifying the registry key HKLM\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile.^[53]

Routinely check account role permissions to ensure only expected users and roles have permission to modify system firewalls.

Ensure proper process and file permissions are in place to prevent adversaries from disabling or modifying firewall settings.

Ensure proper Registry permissions are in place to prevent adversaries from disabling or modifying firewall settings.

Ensure proper user permissions are in place to prevent adversaries from disabling or modifying firewall settings.