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T1132.001 Standard Encoding

Adversaries may encode data with a standard data encoding system to make the content of command and control traffic more difficult to detect. Command and control (C2) information can be encoded using a standard data encoding system that adheres to existing protocol specifications. Common data encoding schemes include ASCII, Unicode, hexadecimal, Base64, and MIME.1 2 Some data encoding systems may also result in data compression, such as gzip.

Item Value
ID T1132.001
Sub-techniques T1132.001, T1132.002
Tactics TA0011
Platforms Linux, Windows, macOS
Permissions required User
Version 1.0
Created 14 March 2020
Last Modified 14 March 2020

Procedure Examples

ID Name Description
S0045 ADVSTORESHELL C2 traffic from ADVSTORESHELL is encrypted, then encoded with Base64 encoding.68
G0073 APT19 An APT19 HTTP malware variant used Base64 to encode communications to the C2 server.80
G0064 APT33 APT33 has used base64 to encode command and control traffic.83
S0373 Astaroth Astaroth encodes data using Base64 before sending it to the C2 server. 57
S0129 AutoIt backdoor AutoIt backdoor has sent a C2 response that was base64-encoded.40
S0414 BabyShark BabyShark has encoded data using certutil before exfiltration.34
S0093 Backdoor.Oldrea Some Backdoor.Oldrea samples use standard Base64 + bzip2, and some use standard Base64 + reverse XOR + RSA-2048 to decrypt data received from C2 servers.24
S0128 BADNEWS BADNEWS encodes C2 traffic with base64.404243
S0268 Bisonal Bisonal has encoded binary data with Base64 and ASCII.6261
S0520 BLINDINGCAN BLINDINGCAN has encoded its C2 traffic with Base64.5
G0060 BRONZE BUTLER Several BRONZE BUTLER tools encode data with base64 when posting it to a C2 server.12
S0014 BS2005 BS2005 uses Base64 encoding for communication in the message body of an HTTP request.64
S0030 Carbanak Carbanak encodes the message body of HTTP traffic with Base64.6667
S0631 Chaes Chaes has used Base64 to encode C2 communications.36
S0674 CharmPower CharmPower can send additional modules over C2 encoded with base64.16
S0144 ChChes ChChes can encode C2 data with a custom technique that utilizes Base64.7071
S0154 Cobalt Strike Cobalt Strike can use Base64, URL-safe Base64, or NetBIOS encoding in its C2 traffic.28
S0338 Cobian RAT Cobian RAT obfuscates communications with the C2 server using Base64 encoding.56
S0137 CORESHELL CORESHELL C2 messages are Base64-encoded.41
S0673 DarkWatchman DarkWatchman encodes data using hexadecimal representation before sending it to the C2 server.25
S0187 Daserf Daserf uses custom base64 encoding to obfuscate HTTP traffic.12
S0354 Denis Denis encodes the data sent to the server in Base64.23
S0200 Dipsind Dipsind encodes C2 traffic with base64.26
S0472 down_new down_new has the ability to base64 encode C2 communications.38
S0377 Ebury Ebury has encoded C2 traffic in hexadecimal format.30
S0081 Elise Elise exfiltrates data using cookie values that are Base64-encoded.60
S0171 Felismus Some Felismus samples use a custom method for C2 traffic that utilizes Base64.69
S0696 Flagpro Flagpro has encoded bidirectional data communications between a target system and C2 server using Base64.55
S0410 Fysbis Fysbis can use Base64 to encode its C2 traffic.44
S0032 gh0st RAT gh0st RAT has used Zlib to compress C2 communications data before encrypting it.11
S0632 GrimAgent GrimAgent can base64 encode C2 replies.33
G0125 HAFNIUM HAFNIUM has used ASCII encoding for C2 traffic.84
S0170 Helminth For C2 over HTTP, Helminth encodes data with base64 and sends it via the “Cookie” field of HTTP requests. For C2 over DNS, Helminth converts ASCII characters into their hexadecimal values and sends the data in cleartext.32
S0376 HOPLIGHT HOPLIGHT has utilized Zlib compression to obfuscate the communications payload. 52
S0015 Ixeshe Ixeshe uses custom Base64 encoding schemes to obfuscate command and control traffic in the message body of HTTP requests.7475
S0044 JHUHUGIT A JHUHUGIT variant encodes C2 POST data base64.76
S0265 Kazuar Kazuar encodes communications to the C2 server in Base64.37
S0487 Kessel Kessel has exfiltrated data via hexadecimal-encoded subdomain fields of DNS queries.59
S0356 KONNI KONNI has used a custom base64 key to encode stolen data before exfiltration.10
G0032 Lazarus Group A Lazarus Group malware sample encodes data with base64.79
S0409 Machete Machete has used base64 encoding.9
S0459 MechaFlounder MechaFlounder has the ability to use base16 encoded strings in C2.15
S0084 Mis-Type Mis-Type uses Base64 encoding for C2 traffic.17
S0083 Misdat Misdat network traffic is Base64-encoded plaintext.17
S0284 More_eggs More_eggs has used basE91 encoding, along with encryption, for C2 communication.51
G0069 MuddyWater MuddyWater has used tools to encode C2 communications including Base64 encoding.8586
S0385 njRAT njRAT uses Base64 encoding for C2 traffic.19
S0340 Octopus Octopus has encoded C2 communications in Base64.13
S0439 Okrum Okrum has used base64 to encode C2 communication.14
S0264 OopsIE OopsIE encodes data in hexadecimal format over the C2 channel.53
G0040 Patchwork Patchwork used Base64 to encode C2 traffic.81
S0124 Pisloader Responses from the Pisloader C2 server are base32-encoded.73
S0441 PowerShower PowerShower has the ability to encode C2 communications with base64 encoding.7778
S0223 POWERSTATS POWERSTATS encoded C2 traffic with base64.20
S0184 POWRUNER POWRUNER can use base64 encoded C2 communications.58
S0113 Prikormka Prikormka encodes C2 traffic with Base64.39
S0650 QakBot QakBot can Base64 encode system information sent to C2.2122
S0269 QUADAGENT QUADAGENT encodes C2 communications with base64.50
S0458 Ramsay Ramsay has used base64 to encode its C2 traffic.35
S0495 RDAT RDAT can communicate with the C2 via base32-encoded subdomains.29
S0379 Revenge RAT Revenge RAT uses Base64 to encode information sent to the C2 server.8
S0270 RogueRobin RogueRobin base64 encodes strings that are sent to the C2 over its DNS tunnel.45
S0085 S-Type S-Type uses Base64 encoding for C2 traffic.17
G0034 Sandworm Team Sandworm Team‘s BCS-server tool uses base64 encoding and HTML tags for the communication traffic between the C2 server.87
S0053 SeaDuke SeaDuke C2 traffic is base64-encoded.63
S0610 SideTwist SideTwist has used Base64 for encoded C2 traffic.27
S0633 Sliver Sliver can use standard encoding techniques like gzip and hex to ASCII to encode the C2 communication payload.4
S0649 SMOKEDHAM SMOKEDHAM has encoded its C2 traffic with Base64.18
S0543 Spark Spark has encoded communications with the C2 server with base64.31
S0374 SpeakUp SpeakUp encodes C&C communication using Base64. 54
S0603 Stuxnet Stuxnet transforms encrypted binary data into an ASCII string in order to use it as a URL parameter value.47
S0559 SUNBURST SUNBURST used Base64 encoding in its C2 traffic.72
G0127 TA551 TA551 has used encoded ASCII text for initial C2 communications.48
S0678 Torisma Torisma has encoded C2 communications with Base64.7
S0266 TrickBot TrickBot can Base64-encode C2 commands.46
G0081 Tropic Trooper Tropic Trooper has used base64 encoding to hide command strings delivered from the C2.82
S0476 Valak Valak has returned C2 data as encoded ASCII.48
S0514 WellMess WellMess has used Base64 encoding to uniquely identify communication to and from the C2.65
S0653 xCaon xCaon has used Base64 to encode its C2 traffic.6
S0251 Zebrocy Zebrocy has used URL/Percent Encoding on data exfiltrated via HTTP POST requests.49

Mitigations

ID Mitigation Description
M1031 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 C2 signatures over time or construct protocols in such a way as to avoid detection by common defensive tools.

Detection

ID Data Source Data Component
DS0029 Network Traffic Network Traffic Content

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