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Exfiltration Over Alternative Protocol
Adversaries may steal data by exfiltrating it over a different protocol than that of the existing command and control channel. The data may also be sent to an alternate network location from the main command and control server.
Alternate protocols include FTP, SMTP, HTTP/S, DNS, SMB, or any other network protocol not being used as the main command and control channel. Different protocol channels could also include Web services such as cloud storage. Adversaries may also opt to encrypt and/or obfuscate these alternate channels.
Exfiltration Over Alternative Protocol can be done using various common operating system utilities such as Net/SMB or FTP.[1]
Procedure Examples
| Name | Description |
|---|---|
| Hydraq |
Hydraq connects to a predefined domain on port 443 to exfil gathered information.[3] |
| PoetRAT |
PoetRAT has used a .NET tool named dog.exe to exiltrate information over an e-mail account.[4] |
Mitigations
| Mitigation | Description |
|---|---|
| Filter Network Traffic |
Enforce proxies and use dedicated servers for services such as DNS and only allow those systems to communicate over respective ports/protocols, instead of all systems within a network. |
| Network Intrusion Prevention |
Network intrusion detection and prevention systems that use network signatures to identify traffic for specific adversary command and control infrastructure and malware can be used to mitigate activity at the network level. |
| Network Segmentation |
Follow best practices for network firewall configurations to allow only necessary ports and traffic to enter and exit the network.[2] |
Detection
Analyze network data for uncommon data flows (e.g., a client sending significantly more data than it receives from a server). Processes utilizing the network that do not normally have network communication or have never been seen before are suspicious. Analyze packet contents to detect communications that do not follow the expected protocol behavior for the port that is being used. [5]