Technique with 2 sub-techniques.View on attack.mitre.org
Adversaries may use traffic signaling to hide open ports or other malicious functionality used for persistence or command and control. Traffic signaling involves the use of a magic value or sequence that must be sent to a system to trigger a special response, such as opening a closed port or executing a malicious task. This may take the form of sending a series of packets with certain characteristics before a port will be opened that the adversary can use for command and control. Usually this series of packets consists of attempted connections to a predefined sequence of closed ports (i.e. Port Knocking), but can involve unusual flags, specific strings, or other unique characteristics. After the sequence is completed, opening a port may be accomplished by the host-based firewall, but could also be implemented by custom software.
Adversaries may also communicate with an already open port, but the service listening on that port will only respond to commands or trigger other malicious functionality if passed the appropriate magic value(s).
The observation of the signal packets to trigger the communication can be conducted through different methods. One means, originally implemented by Cd00r , is to use the libpcap libraries to sniff for the packets in question. Another method leverages raw sockets, which enables the malware to use ports that are already open for use by other programs.
On network devices, adversaries may use crafted packets to enable Network Device Authentication for standard services offered by the device such as telnet. Such signaling may also be used to open a closed service port such as telnet, or to trigger module modification of malware implants on the device, adding, removing, or changing malicious capabilities. Adversaries may use crafted packets to attempt to connect to one or more (open or closed) ports, but may also attempt to connect to a router interface, broadcast, and network address IP on the same port in order to achieve their goals and objectives. To enable this traffic signaling on embedded devices, adversaries must first achieve and leverage Patch System Image due to the monolithic nature of the architecture.
Adversaries may also use the Wake-on-LAN feature to turn on powered off systems. Wake-on-LAN is a hardware feature that allows a powered down system to be powered on, or woken up, by sending a magic packet to it. Once the system is powered on, it may become a target for lateral movement.
Rules on DetectionCode tagged with T1205 or one of its sub-techniques.
| Used by | Procedure example |
|---|---|
| GroupKimsuky | Kimsuky has used TRANSLATEXT to redirect clients to legitimate Gmail, Naver or Kakao pages if the clients connect with no parameters. |
| GroupMustang Panda | Mustang Panda has utilized a magic value in C2 communications and only executes in memory when response packets match specific values of “17 03 03” or “46 77 4d”. |
| GroupUNC3886 | UNC3886 has used the TABLEFLIP traffic redirection utility to listen for specialized command packets on compromised FortiManager devices. |
| Used by | Procedure example |
|---|---|
| MalwareBRUSHFIRE | BRUSHFIRE has monitored inbound VPN traffic to compromised appliances until specific inbound packets contain a specific magic string/pattern instead of external beaconing. |
| MalwareBUSHWALK | BUSHWALK can modify the `DSUserAgentCap.pm` Perl module on Ivanti Connect Secure VPNs and either activate or deactivate depending on the value of the user agent in incoming HTTP requests. |
| MalwareChaos | Chaos provides a reverse shell is triggered upon receipt of a packet with a special string, sent to any port. |
| MalwareJ-magic | J-magic can monitor TCP traffic for packets containing one of five different predefined parameters and will spawn a reverse shell if one of the parameters and the proper response string to a subsequent challenge is received. |
| MalwareKobalos | Kobalos is triggered by an incoming TCP connection to a legitimate service from a specific source port. |
| MalwareMini Shai-Hulud | Mini Shai-Hulud has examined commit messages for a keyword followed by base64 encoded segments to validate communications and to execute subsequent actions to include exfiltration. |
| MalwarePandora | Pandora can identify if incoming HTTP traffic contains a token and if so it will intercept the traffic and process the received command. |
| MalwarePenquin | Penquin will connect to C2 only after sniffing a "magic packet" value in TCP or UDP packets matching specific conditions. |
| Used by | Procedure example |
|---|---|
| CampaignCutting Edge | During Cutting Edge, threat actors sent a magic 48-byte sequence to enable the PITSOCK backdoor to communicate via the `/tmp/clientsDownload.sock` socket. |
| CampaignRedPenguin | During RedPenguin, UNC3886 leveraged malware capable of inpecting packets for a magic-string to activate backdoor functionalities. |
Data from MITRE ATT&CK® (Enterprise). ATT&CK® is a registered trademark of The MITRE Corporation.
