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T1573.001 Symmetric Cryptography

Adversaries may employ a known symmetric encryption algorithm to conceal command and control traffic rather than relying on any inherent protections provided by a communication protocol. Symmetric encryption algorithms use the same key for plaintext encryption and ciphertext decryption. Common symmetric encryption algorithms include AES, DES, 3DES, Blowfish, and RC4.

Item Value
ID T1573.001
Sub-techniques T1573.001, T1573.002
Tactics TA0011
Platforms ESXi, Linux, Network Devices, Windows, macOS
Version 1.2
Created 16 March 2020
Last Modified 24 October 2025

Procedure Examples

ID Name Description
C0057 3CX Supply Chain Attack During the 3CX Supply Chain Attack, AppleJeus’s VEILEDSIGNAL communication module supports three commands to conduct the following actions: send implant data, execute shellcode, and terminate itself.192
S0066 3PARA RAT 3PARA RAT command and control commands are encrypted within the HTTP C2 channel using the DES algorithm in CBC mode with a key derived from the MD5 hash of the string HYF54&%9&jkMCXuiS. 3PARA RAT will use an 8-byte XOR key derived from the string HYF54&%9&jkMCXuiS if the DES decoding fails14
S0065 4H RAT 4H RAT obfuscates C2 communication using a 1-byte XOR with the key 0xBE.14
S0045 ADVSTORESHELL A variant of ADVSTORESHELL encrypts some C2 with 3DES.97
G0007 APT28 APT28 installed a Delphi backdoor that used a custom algorithm for C2 communications.189
G0064 APT33 APT33 has used AES for encryption of command and control traffic.35
S0438 Attor Attor has encrypted data symmetrically using a randomly generated Blowfish (OFB) key which is encrypted with a public RSA key.31
S0344 Azorult Azorult can encrypt C2 traffic using XOR.1819
S0245 BADCALL BADCALL encrypts C2 traffic using an XOR/ADD cipher.57
S0128 BADNEWS BADNEWS encrypts C2 data with a ROR by 3 and an XOR by 0x23.2728
S0234 Bandook Bandook has used AES encryption for C2 communication.154
S0534 Bazar Bazar can send C2 communications with XOR encryption.93
S0127 BBSRAT BBSRAT uses a custom encryption algorithm on data sent back to the C2 server over HTTP.96
S0574 BendyBear BendyBear communicates to a C2 server over port 443 using modified RC4 and XOR-encrypted chunks.114
S0268 Bisonal Bisonal variants reported on in 2014 and 2015 used a simple XOR cipher for C2. Some Bisonal samples encrypt C2 communications with RC4.202221
S0520 BLINDINGCAN BLINDINGCAN has encrypted its C2 traffic with RC4.159
S0486 Bonadan Bonadan can XOR-encrypt C2 communications.47
S1226 BOOKWORM BOOKWORM has used encryption and compression algorithms to obfuscate the traffic between the system and C2 server, methods observed included RC4, AES, XOR with 0x5a, and LZO. 112
G0060 BRONZE BUTLER BRONZE BUTLER has used RC4 encryption (for Datper malware) and AES (for xxmm malware) to obfuscate HTTP traffic. BRONZE BUTLER has also used a tool called RarStar that encodes data with a custom XOR algorithm when posting it to a C2 server.148
S1039 Bumblebee Bumblebee can encrypt C2 requests and responses with RC4128
S0077 CallMe CallMe uses AES to encrypt C2 traffic.66
S0030 Carbanak Carbanak encrypts the message body of HTTP traffic with RC2 (in CBC mode). Carbanak also uses XOR with random keys for its communications.123124
S0348 Cardinal RAT Cardinal RAT uses a secret key with a series of XOR and addition operations to encrypt C2 traffic.69
S1224 CASTLETAP CASTLETAP can receive a 9-byte XOR encrypted activation string in the payload of an ICMP echo request packet.85
S0220 Chaos Chaos provides a reverse shell connection on 8338/TCP, encrypted via AES.34
S0674 CharmPower CharmPower can send additional modules over C2 encrypted with a simple substitution cipher.56
S0144 ChChes ChChes can encrypt C2 traffic with AES or RC4.160161
S0023 CHOPSTICK CHOPSTICK encrypts C2 communications with RC4.167
S0154 Cobalt Strike Cobalt Strike has the ability to use AES-256 symmetric encryption in CBC mode with HMAC-SHA-256 to encrypt task commands and XOR to encrypt shell code and configuration data.142
S0244 Comnie Comnie encrypts command and control communications with RC4.113
G1052 Contagious Interview Contagious Interview has encrypted C2 traffic using RC4.186
S0137 CORESHELL CORESHELL C2 messages are encrypted with custom stream ciphers using six-byte or eight-byte keys.168
S0050 CosmicDuke CosmicDuke contains a custom version of the RC4 algorithm that includes a programming error.173
G0012 Darkhotel Darkhotel has used AES-256 and 3DES for C2 communications.176
S0187 Daserf Daserf uses RC4 encryption to obfuscate HTTP traffic.148
S0021 Derusbi Derusbi obfuscates C2 traffic with variable 4-byte XOR keys.121
S0200 Dipsind Dipsind encrypts C2 data with AES256 in ECB mode.55
S0472 down_new down_new has the ability to AES encrypt C2 communications.170
S0134 Downdelph Downdelph uses RC4 to encrypt C2 responses.111
S0384 Dridex Dridex has encrypted traffic with RC4.7
S0038 Duqu The Duqu command and control protocol’s data stream can be encrypted with AES-CBC.94
S0377 Ebury Ebury has encrypted C2 traffic using the client IP address, then encoded it as a hexadecimal string.90
S0081 Elise Elise encrypts exfiltrated data with RC4.24
S0082 Emissary The C2 server response to a beacon sent by a variant of Emissary contains a 36-character GUID value that is used as an encryption key for subsequent network communications. Some variants of Emissary use various XOR operations to encrypt C2 data.65
S0367 Emotet Emotet is known to use RSA keys for encrypting C2 traffic. 12
S0091 Epic Epic encrypts commands from the C2 server using a hardcoded key.133
S0569 Explosive Explosive has encrypted communications with the RC4 method.99
S0076 FakeM The original variant of FakeM encrypts C2 traffic using a custom encryption cipher that uses an XOR key of “YHCRA” and bit rotation between each XOR operation. Some variants of FakeM use RC4 to encrypt C2 traffic.66
S0181 FALLCHILL FALLCHILL encrypts C2 data with RC4 encryption.5253
S0512 FatDuke FatDuke can AES encrypt C2 communications.152
S0171 Felismus Some Felismus samples use a custom encryption method for C2 traffic that utilizes AES and multiple keys.171
S0381 FlawedAmmyy FlawedAmmyy has used SEAL encryption during the initial C2 handshake.132
S0661 FoggyWeb FoggyWeb has used a dynamic XOR key and custom XOR methodology for C2 communications.158
C0001 Frankenstein During Frankenstein, the threat actors communicated with C2 via an encrypted RC4 byte stream and AES-CBC.193
S1144 FRP FRP can use STCP (Secret TCP) with a preshared key to encrypt services exposed to public networks.5
S0168 Gazer Gazer uses custom encryption for C2 that uses 3DES.117118
S0032 gh0st RAT gh0st RAT uses RC4 and XOR to encrypt C2 traffic.105
S0342 GreyEnergy GreyEnergy encrypts communications using AES256.129
S0632 GrimAgent GrimAgent can use an AES key to encrypt C2 communications.79
S0132 H1N1 H1N1 encrypts C2 traffic using an RC4 key.146
S0037 HAMMERTOSS Before being appended to image files, HAMMERTOSS commands are encrypted with a key composed of both a hard-coded value and a string contained on that day’s tweet. To decrypt the commands, an investigator would need access to the intended malware sample, the day’s tweet, and the image file containing the command.59
S1229 Havoc Havoc can send an AES encrypted check-in request to the C2 server.3637
S0170 Helminth Helminth encrypts data sent to its C2 server over HTTP with RC4.42
S0087 Hi-Zor Hi-Zor encrypts C2 traffic with a double XOR using two distinct single-byte keys.51
S0394 HiddenWasp HiddenWasp uses an RC4-like algorithm with an already computed PRGA generated key-stream for network communication.74
G0126 Higaisa Higaisa used AES-128 to encrypt C2 traffic.187
S0009 Hikit Hikit performs XOR encryption.40
S0431 HotCroissant HotCroissant has compressed network communications and encrypted them with a custom stream cipher.4344
S0068 httpclient httpclient encrypts C2 content with XOR using a single byte, 0x12.14
S0203 Hydraq Hydraq C2 traffic is encrypted using bitwise NOT and XOR operations.95
S0537 HyperStack HyperStack has used RSA encryption for C2 communications.116
S1022 IceApple The IceApple Result Retriever module can AES encrypt C2 responses.155
G0100 Inception Inception has encrypted network communications with AES.188
S0260 InvisiMole InvisiMole uses variations of a simple XOR encryption routine for C&C communications.9
S0271 KEYMARBLE KEYMARBLE uses a customized XOR algorithm to encrypt C2 communications.153
S0641 Kobalos Kobalos’s post-authentication communication channel uses a 32-byte-long password with RC4 for inbound and outbound traffic.103104
S0162 Komplex The Komplex C2 channel uses an 11-byte XOR algorithm to hide data.138
S0356 KONNI KONNI has used AES to encrypt C2 traffic.147
S1160 Latrodectus Latrodectus can send RC4 encrypted data over C2 channels.135136134
G0032 Lazarus Group Several Lazarus Group malware families encrypt C2 traffic using custom code that uses XOR with an ADD operation and XOR with a SUB operation. Another Lazarus Group malware sample XORs C2 traffic. Other Lazarus Group malware uses Caracachs encryption to encrypt C2 payloads. Lazarus Group has also used AES to encrypt C2 traffic.178177179180
S0395 LightNeuron LightNeuron uses AES to encrypt C2 traffic.98
S1119 LIGHTWIRE LIGHTWIRE can RC4 encrypt C2 commands.73
S1202 LockBit 3.0 LockBit 3.0 can encrypt C2 communications with AES.15
S0582 LookBack LookBack uses a modified version of RC4 for data transfer.101
S0532 Lucifer Lucifer can perform a decremental-xor encryption on the initial C2 request before sending it over the wire.48
S1141 LunarWeb LunarWeb can send AES encrypted C2 commands.61
S0010 Lurid Lurid performs XOR encryption.32
S0409 Machete Machete has used AES to exfiltrate documents.17
S1060 Mafalda Mafalda can encrypt its C2 traffic with RC4.106
S1169 Mango Mango can receive XOR-encrypted commands from C2.60
S1059 metaMain metaMain can encrypt the data that it sends and receives from the C2 server using an RC4 encryption algorithm.106162
S0455 Metamorfo Metamorfo has encrypted C2 commands with AES-256.164
S1026 Mongall Mongall has the ability to RC4 encrypt C2 communications.68
S0149 MoonWind MoonWind encrypts C2 traffic using RC4 with a static key.75
S0284 More_eggs More_eggs has used an RC4-based encryption method for its C2 communications.39
S0256 Mosquito Mosquito uses a custom encryption algorithm, which consists of XOR and a stream that is similar to the Blum Blum Shub algorithm.54
G0069 MuddyWater MuddyWater has used AES to encrypt C2 responses.185
G0129 Mustang Panda Mustang Panda has encrypted C2 communications with RC4.139175 Mustang Panda has also leveraged encryption and compression algorithms to obfuscate the traffic between the system and C2 server, methods observed included RC4, AES, XOR with 0x5a, and LZO.112
S0336 NanoCore NanoCore uses DES to encrypt the C2 traffic.120
S0272 NDiskMonitor NDiskMonitor uses AES to encrypt certain information sent over its C2 channel.28
S0630 Nebulae Nebulae can use RC4 and XOR to encrypt C2 communications.156
S0034 NETEAGLE NETEAGLE will decrypt resources it downloads with HTTP requests by using RC4 with the key “ScoutEagle.”16
S0198 NETWIRE NETWIRE can use AES encryption for C2 data transferred.41
S1106 NGLite NGLite will use an AES encrypted channel for command and control purposes, in one case using the key WHATswrongwithUu.119
S1100 Ninja Ninja can XOR and AES encrypt C2 messages.76
S0439 Okrum Okrum uses AES to encrypt network traffic. The key can be hardcoded or negotiated with the C2 server in the registration phase. 126
C0022 Operation Dream Job During Operation Dream Job, Lazarus Group used an AES key to communicate with their C2 server.190
S0352 OSX_OCEANLOTUS.D OSX_OCEANLOTUS.D encrypts data sent back to the C2 using AES in CBC mode with a null initialization vector (IV) and a key sent from the server that is padded to 32 bytes.64
S0664 Pandora Pandora has the ability to encrypt communications with D3DES.26
S1145 Pikabot Earlier Pikabot variants use a custom encryption procedure leveraging multiple mechanisms including AES with multiple rounds of Base64 encoding for its command and control communication.77 Later Pikabot variants eliminate the use of AES and instead use RC4 encryption for transmitted information.78
S1031 PingPull PingPull can use AES, in cipher block chaining (CBC) mode padded with PKCS5, to encrypt C2 server communications.174
S0501 PipeMon PipeMon communications are RC4 encrypted.115
S0254 PLAINTEE PLAINTEE encodes C2 beacons using XOR.157
S0435 PLEAD PLEAD has used RC4 encryption to download modules.166
S0013 PlugX PlugX can use RC4 encryption in C2 communications.139140
S0012 PoisonIvy PoisonIvy uses the Camellia cipher to encrypt communications.127
S0371 POWERTON POWERTON has used AES for encrypting C2 traffic.35
S0113 Prikormka Prikormka encrypts some C2 traffic with the Blowfish cipher.13
S1228 PUBLOAD PUBLOAD has used RC4 encryption in C2 communications.828384
S0650 QakBot QakBot can RC4 encrypt strings in C2 communication.67
S0262 QuasarRAT QuasarRAT uses AES with a hardcoded pre-shared key to encrypt network communication.342
S1076 QUIETCANARY QUIETCANARY can RC4 encrypt C2 communications.29
S0629 RainyDay RainyDay can use RC4 to encrypt C2 communications.156
S0495 RDAT RDAT has used AES ciphertext to encode C2 communications.91
G1039 RedCurl RedCurl has used AES-128 CBC to encrypt C2 communications.183
S0153 RedLeaves RedLeaves has encrypted C2 traffic with RC4, previously using keys of 88888888 and babybear.131
C0056 RedPenguin During RedPenguin, UNC3886 malware used the RC4 cipher to encrypt outgoing C2 messages.191
S0433 Rifdoor Rifdoor has encrypted command and control (C2) communications with a stream cipher.43
S1222 RIFLESPINE RIFLESPINE can use the AES algorithm to encrypt C2 data.45
S0003 RIPTIDE APT12 has used the RIPTIDE RAT, which communicates over HTTP with a payload encrypted with RC4.145
S1078 RotaJakiro RotaJakiro encrypts C2 communication using a combination of AES, XOR, ROTATE encryption, and ZLIB compression.169
S0148 RTM RTM encrypts C2 traffic with a custom RC4 variant.100
S0074 Sakula Sakula encodes C2 traffic with single-byte XOR keys.70
S1099 Samurai Samurai can encrypt C2 communications with AES.76
S1085 Sardonic Sardonic has the ability to use an RC4 key to encrypt communications to and from actor-controlled C2 servers.30
S0053 SeaDuke SeaDuke C2 traffic has been encrypted with RC4 and AES.143144
S0610 SideTwist SideTwist can encrypt C2 communications with a randomly generated key.63
S1110 SLIGHTPULSE SLIGHTPULSE can RC4 encrypt all incoming and outgoing C2 messages.122
S0633 Sliver Sliver can use AES-GCM-256 to encrypt a session key for C2 message exchange.6
S0649 SMOKEDHAM SMOKEDHAM has encrypted its C2 traffic with RC4.8
S0159 SNUGRIDE SNUGRIDE encrypts C2 traffic using AES with a static key.165
S0627 SodaMaster SodaMaster can use RC4 to encrypt C2 communications.130
S1166 Solar Solar can XOR encrypt C2 communications.60
S0615 SombRAT SombRAT has encrypted its C2 communications with AES.107
S1227 StarProxy StarProxy has leveraged two 256-byte XOR keys to encrypt and decrypt network packets using a custom algorithm.10
G0038 Stealth Falcon Stealth Falcon malware encrypts C2 traffic using RC4 with a hard-coded key.184
S1034 StrifeWater StrifeWater can encrypt C2 traffic using XOR with a hard coded key.33
S0603 Stuxnet Stuxnet encodes the payload of system information sent to the command and control servers using a one byte 0xFF XOR key. Stuxnet also uses a 31-byte long static byte string to XOR data sent to command and control servers. The servers use a different static key to encrypt replies to the implant.88
S0559 SUNBURST SUNBURST encrypted C2 traffic using a single-byte-XOR cipher.38
S0060 Sys10 Sys10 uses an XOR 0x1 loop to encrypt its C2 domain.23
S0663 SysUpdate SysUpdate has used DES to encrypt all C2 communications.11
S0011 Taidoor Taidoor uses RC4 to encrypt the message body of HTTP content.4950
S0586 TAINTEDSCRIBE TAINTEDSCRIBE uses a Linear Feedback Shift Register (LFSR) algorithm for network encryption.102
S1193 TAMECAT TAMECAT has used AES to encrypt C2 traffic.71
S1223 THINCRUST THINCRUST can process RSA encryted C2 commands.85
S1239 TONESHELL TONESHELL has used RC4 encryption in C2 communications.84 TONESHELL variants used a randomly generated variable length (0x20 - 0x200 bytes) rolling XOR key to encrypt and decrypt network packets.10
S0678 Torisma Torisma has encrypted its C2 communications using XOR and VEST-32.89
S0266 TrickBot TrickBot uses a custom crypter leveraging Microsoft’s CryptoAPI to encrypt C2 traffic.86Newer versions of TrickBot have been known to use bcrypt to encrypt and digitally sign responses to their C2 server. 87
S1196 Troll Stealer Troll Stealer encrypts data sent to command and control infrastructure using a combination of RC4 and RSA-4096 algorithms.151
S0436 TSCookie TSCookie has encrypted network communications with RC4.137
S0333 UBoatRAT UBoatRAT encrypts instructions in its C2 network payloads using a simple XOR cipher.163
S0275 UPPERCUT Some versions of UPPERCUT have used the hard-coded string “this is the encrypt key” for Blowfish encryption when communicating with a C2. Later versions have hard-coded keys uniquely for each C2 address.80
S0022 Uroburos Uroburos can encrypt the data beneath its http2 or tcp encryption at the session layer with CAST-128, using a different key for incoming and outgoing data.62
S1218 VIRTUALPIE VIRTUALPIE can use a custom RC4 encrypted protocol for C2 communications.4645
S0180 Volgmer Volgmer uses a simple XOR cipher to encrypt traffic and files.72
G1017 Volt Typhoon Volt Typhoon has used a version of the Awen web shell that employed AES encryption and decryption for C2 communications.182
S0670 WarzoneRAT WarzoneRAT can encrypt its C2 with RC4 with the password warzone160\x00.58
S0514 WellMess WellMess can encrypt HTTP POST data using RC6 and a dynamically generated AES key encrypted with a hard coded RSA public key.108109110
S0430 Winnti for Linux Winnti for Linux has used a custom TCP protocol with four-byte XOR for command and control (C2).81
S0141 Winnti for Windows Winnti for Windows can XOR encrypt C2 traffic.25
S1115 WIREFIRE WIREFIRE can AES encrypt process output sent from compromised devices to C2.141
S1065 Woody RAT Woody RAT can use AES-CBC to encrypt data sent to its C2 server.172
S0653 xCaon xCaon has encrypted data sent to the C2 server using a XOR key.125
S0658 XCSSET XCSSET uses RC4 encryption over TCP to communicate with its C2 server.92
S0230 ZeroT ZeroT has used RC4 to encrypt C2 traffic.149150
S1114 ZIPLINE ZIPLINE can use AES-128-CBC to encrypt data for both upload and download.73
G0128 ZIRCONIUM ZIRCONIUM has used AES encrypted communications in C2.181

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.

References


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