T1048
Exfiltration Over Alternative Protocol
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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. Adversaries may also opt to encrypt and/or obfuscate these alternate channels.
If this is happening now
Checklists and playbooks to open while the alert is still live.
Data theft extortion response plan: verify the claim, find the way out, own the notification
An extortion demand with nothing encrypted, or your name on a leak site. Three questions run in parallel with three owners: is the claim real, what left and how, and what you are obliged to say and to whom. A plan for answering each one on evidence rather than on the attacker's framing.
Insider threat response plan: evidence, proportion and the employee who may have done nothing
The response where the usual instincts are wrong. Speed matters less than lawfulness, the suspect is a colleague with rights, and half of these turn out to be misunderstanding. A plan for investigating quietly, preserving what you would need, and being able to stand behind how you did it.
Suspected data theft by an insider
A resignation with unusual file access, a DLP alert, or an unexplained large transfer.
Data leaving with a person
A resignation with an unusual access pattern behind it, a bulk download, or a report from a manager.
Detect it
Hunts and rules you can run, each stating what it needs and what else it returns.
Sigma network pack: four rules for DNS, proxy and firewall logs
Long DNS labels, scripting-engine user agents at the proxy, executables fetched from a bare IP address, and SMB leaving the network. Written for the log sources most estates already collect and rarely alert on.
Practise it
Labs, timelines, evidence packs and tabletop scenarios to work before you need to.
DNS with something in the labels: a small constructed capture
Sixty DNS queries from one workstation, fifteen of them TXT lookups whose first label is 56 characters of base32. Small enough to read packet by packet, and generated by a script, so nothing in it came from a real network.
Read
Analyses, case studies, guides, references and interview questions.
Finding DNS tunnelling in a 4 GB capture without a signature
Entropy, subdomain cardinality and query-rate shape. Three statistics that find a covert channel faster than any rule matching a known tool.
how MITRE says to see it
Behavioral Detection Strategy for Exfiltration Over Alternative Protocol
- Detects unusual outbound file transfer behavior using protocols like FTP, SMB, SMTP, or DNS, involving non-standard processes, off-hour activity, or uncommonly high volume.
- Detects file exfiltration using tools like curl, scp, or custom binaries over protocols such as FTP, HTTP/S, or DNS tunneling, especially outside baseline user behavior.
- Detects non-native file transfer via curl, Python scripts, or AppleScript using uncommon protocols like FTP, SMTP, or DNS exfiltration through mDNSResponder abuse.
- Detects access to cloud APIs or CLI tools to move or sync files from sensitive buckets to external endpoints using protocols like HTTPS or S3 APIs.
what reduces it
- M1031 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.
- M1037 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. Cloud service providers support IP-based restrictions when accessing cloud resources.
- M1057 Data Loss Prevention. Data loss prevention can detect and block sensitive data being uploaded via web browsers.
- M1030 Network Segmentation. Follow best practices for network firewall configurations to allow only necessary ports and traffic to enter and exit the network.
- M1018 User Account Management. Configure user permissions groups and roles for access to cloud storage. Implement strict Identity and Access Management (IAM) controls to prevent access to storage solutions except for the applications, users, and services that require access.
- M1022 Restrict File and Directory Permissions. Use access control lists on cloud storage systems and objects.