Exfiltration Over C2 Channel

Adversaries may steal data by exfiltrating it over an existing command and control channel. Stolen data is encoded into the normal communications channel using the same protocol as command and control communications.

ID: T1041
Sub-techniques:  No sub-techniques
Tactic: Exfiltration
Platforms: Linux, Windows, macOS
Data Sources: Netflow/Enclave netflow, Packet capture, Process monitoring, Process use of network
Requires Network:  Yes
Version: 2.0
Created: 31 May 2017
Last Modified: 12 March 2020

Procedure Examples

Name Description
ADVSTORESHELL

ADVSTORESHELL exfiltrates data over the same channel used for C2.[8]

APT3

APT3 has a tool that exfiltrates data over the C2 channel.[42]

APT32

APT32's backdoor has exfiltrated data using the already opened channel with its C&C server.[44]

Astaroth

Astaroth exfiltrates collected information from its r1.log file to the external C2 server. [16]

Attor

Attor has exfiltrated data over the C2 channel.[27]

BACKSPACE

Adversaries can direct BACKSPACE to upload files to the C2 Server.[7]

Bankshot

Bankshot exfiltrates data over its C2 channel.[6]

CallMe

CallMe exfiltrates data to its C2 server over the same protocol as C2 communications.[10]

Cannon

Cannon exfiltrates collected data over email via SMTP/S and POP3/S C2 channels.[13]

DustySky

DustySky has exfiltrated data to the C2 server.[30]

Dyre

Dyre has the ability to send information staged on a compromised host externally to C2.[35]

Emotet

Emotet has been seen exfiltrating system information stored within cookies sent within an HTTP GET request back to its C2 servers. [15]

Empire

Empire can send data gathered from a target through the command and control channel.[3]

Frankenstein

Frankenstein has collected information via Empire, which is automatically sent the data back to the adversary's C2.[47]

Gamaredon Group

A Gamaredon Group file stealer can transfer collected files to a hardcoded C2 server.[11]

Goopy

Goopy has the ability to exfiltrate data over the Microsoft Outlook C2 channel.[37]

HAWKBALL

HAWKBALL has sent system information and files over the C2 channel.[19]

HOPLIGHT

HOPLIGHT has used its C2 channel to exfiltrate data.[18]

HotCroissant

HotCroissant has the ability to download files from the infected host to the command and control (C2) server.[26]

Imminent Monitor

Imminent Monitor has uploaded a file containing debugger logs, network information and system information to the C2.[4]

Ke3chang

Ke3chang transferred compressed and encrypted RAR files containing exfiltration through the established backdoor command and control channel during operations.[43]

Kimsuky

Kimsuky has exfiltrated data over its email C2 channel.[46]

Lazarus Group

Lazarus Group malware IndiaIndia saves information gathered about the victim to a file that is uploaded to one of its 10 C2 servers. Another Lazarus Group malware sample also performs exfiltration over the C2 channel.[38][39][40]

LightNeuron

LightNeuron exfiltrates data over its email C2 channel.[20]

Lokibot

Lokibot has the ability to initiate contact with command and control (C2) to exfiltrate stolen data.[32]

Machete

Machete's collected data is exfiltrated over the same channel used for C2.[22]

MechaFlounder

MechaFlounder has the ability to send the compromised user's account name and hostname within a URL to C2.[33]

MobileOrder

MobileOrder exfiltrates data to its C2 server over the same protocol as C2 communications.[10]

MuddyWater

MuddyWater has used C2 infrastructure to receive exfiltrated data.[49]

NETEAGLE

NETEAGLE is capable of reading files over the C2 channel.[7]

Okrum

Data exfiltration is done by Okrum using the already opened channel with the C2 server.[28]

OopsIE

OopsIE can upload files from the victim's machine to its C2 server.[14]

PowerShower

PowerShower has used a PowerShell document stealer module to pack and exfiltrate .txt, .pdf, .xls or .doc files smaller than 5MB that were modified during the past two days.[29]

Proxysvc

Proxysvc performs data exfiltration over the control server channel using a custom protocol.[12]

Psylo

Psylo exfiltrates data to its C2 server over the same protocol as C2 communications.[10]

Pteranodon

Pteranodon exfiltrates screenshot files to its C2 server.[11]

Pupy

Pupy can send screenshots files, keylogger data, files, and recorded audio back to the C2 server.[2]

Remexi

Remexi performs exfiltration over BITSAdmin, which is also used for the C2 channel.[17]

Rising Sun

Rising Sun can send data gathered from the infected machine via HTTP POST request to the C2.[31]

ROKRAT

ROKRAT sends collected files back over same C2 channel.[9]

Sandworm Team

Sandworm Team has sent system information to its C2 server using HTTP.[50]

ShimRatReporter

ShimRatReporter sent generated reports to the C2 via HTTP POST requests.[5]

Soft Cell

Soft Cell used Web shells and HTRAN for C2 as well as to exfiltrate data.[45]

Stealth Falcon

After data is collected by Stealth Falcon malware, it is exfiltrated over the existing C2 channel.[41]

TajMahal

TajMahal has the ability to send collected files over its C2.[34]

Ursnif

Ursnif has used HTTP POSTs to exfil gathered information.[23][24][25]

Valak

Valak has the ability to exfiltrate data over the C2 channel.[36]

Wizard Spider

Wizard Spider has exfiltrated domain credentials and network enumeration information over command and control (C2) channels.[48]

Zebrocy

Zebrocy has exfiltrated data to the designated C2 server using HTTP POST requests.[21]

Mitigations

Mitigation Description
Network Intrusion Prevention

Network intrusion detection and prevention systems that use network signatures to identify traffic for specific adversary malware can be used to mitigate activity at the network level. Signatures are often for unique indicators within protocols and may be based on the specific obfuscation technique used by a particular adversary or tool, and will likely be different across various malware families and versions. Adversaries will likely change tool command and control signatures over time or construct protocols in such a way to avoid detection by common defensive tools. [1]

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. [1]

References

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