Obfuscated Files or Information: Software Packing

Adversaries may perform software packing or virtual machine software protection to conceal their code. Software packing is a method of compressing or encrypting an executable. Packing an executable changes the file signature in an attempt to avoid signature-based detection. Most decompression techniques decompress the executable code in memory. Virtual machine software protection translates an executable's original code into a special format that only a special virtual machine can run. A virtual machine is then called to run this code.[1]

Utilities used to perform software packing are called packers. Example packers are MPRESS and UPX. A more comprehensive list of known packers is available, but adversaries may create their own packing techniques that do not leave the same artifacts as well-known packers to evade defenses.[2]

ID: T1027.002
Sub-technique of:  T1027
Tactic: Defense Evasion
Platforms: Linux, Windows, macOS
Defense Bypassed: Anti-virus, Heuristic detection, Signature-based detection
Contributors: Filip Kafka, ESET
Version: 1.2
Created: 05 February 2020
Last Modified: 30 March 2023

Procedure Examples

ID Name Description
C0025 2016 Ukraine Electric Power Attack

During the 2016 Ukraine Electric Power Attack, Sandworm Team used UPX to pack a copy of Mimikatz.[3]

S0504 Anchor

Anchor has come with a packed payload.[4]

G1007 Aoqin Dragon

Aoqin Dragon has used the Themida packer to obfuscate malicious payloads.[5]

S0622 AppleSeed

AppleSeed has used UPX packers for its payload DLL.[6]

G0016 APT29

APT29 used UPX to pack files.[7]

G0022 APT3

APT3 has been known to pack their tools.[8][9]

G0082 APT38

APT38 has used several code packing methods such as Themida, Enigma, VMProtect, and Obsidium, to pack their implants.[10]

G0087 APT39

APT39 has packed tools with UPX, and has repacked a modified version of Mimikatz to thwart anti-virus detection.[11][12]

G0096 APT41

APT41 uses packers such as Themida to obfuscate malicious files.[13]

S0373 Astaroth

Astaroth uses a software packer called Pe123\RPolyCryptor.[14]

S0638 Babuk

Versions of Babuk have been packed.[15][16][17]

S0534 Bazar

Bazar has a variant with a packed payload.[18][19]

S0268 Bisonal

Bisonal has used the MPRESS packer and similar tools for obfuscation.[20]


BLINDINGCAN has been packed with the UPX packer.[21]

C0017 C0017

During C0017, APT41 used VMProtect to slow the reverse engineering of malicious binaries.[22]

S0020 China Chopper

China Chopper's client component is packed with UPX.[23]

S0611 Clop

Clop has been packed to help avoid detection.[24][25]


The first stage of COATHANGER is delivered as a packed file.[26]

S0614 CostaBricks

CostaBricks can implement a custom-built virtual machine mechanism to obfuscate its code.[27]

S0527 CSPY Downloader

CSPY Downloader has been packed with UPX.[28]

S0625 Cuba

Cuba has a packed payload when delivered.[29]

G0070 Dark Caracal

Dark Caracal has used UPX to pack Bandook.[30]

S0334 DarkComet

DarkComet has the option to compress its payload using UPX or MPRESS.[31]

S0187 Daserf

A version of Daserf uses the MPRESS packer.[32]

S0281 Dok

Dok is packed with an UPX executable packer.[33]

S0695 Donut

Donut can generate packed code modules.[34]

S0694 DRATzarus

DRATzarus's dropper can be packed with UPX.[35]

S0024 Dyre

Dyre has been delivered with encrypted resources and must be unpacked for execution.[36]

S0554 Egregor

Egregor's payloads are custom-packed, archived and encrypted to prevent analysis.[37][38]

G0066 Elderwood

Elderwood has packed malware payloads before delivery to victims.[39]

G1003 Ember Bear

Ember Bear has packed malware to help avoid detection.[40]

S0367 Emotet

Emotet has used custom packers to protect its payloads.[41]

S0512 FatDuke

FatDuke has been regularly repacked by its operators to create large binaries and evade detection.[42]

S0182 FinFisher

A FinFisher variant uses a custom packer.[43][44]

S0628 FYAnti

FYAnti has used ConfuserEx to pack its .NET module.[45]


GALLIUM packed some payloads using different types of packers, both known and custom.[46]

S0588 GoldMax

GoldMax has been packed for obfuscation.[47]

S0342 GreyEnergy

GreyEnergy is packed for obfuscation.[48]

S0132 H1N1

H1N1 uses a custom packing algorithm.[49]

S0601 Hildegard

Hildegard has packed ELF files into other binaries.[50]

S0431 HotCroissant

HotCroissant has used the open source UPX executable packer.[51]

S0398 HyperBro

HyperBro has the ability to pack its payload.[52]

S0483 IcedID

IcedID has packed and encrypted its loader module.[53]

S0283 jRAT

jRAT payloads have been packed.[54]

G0094 Kimsuky

Kimsuky has packed malware with UPX.[6]


KONNI has been packed for obfuscation.[55]

S0513 LiteDuke

LiteDuke has been packed with multiple layers of encryption.[42]

S0447 Lokibot

Lokibot has used several packing methods for obfuscation.[56]

S0532 Lucifer

Lucifer has used UPX packed binaries.[57]

S0409 Machete

Machete has been packed with NSIS.[58]

S0530 Melcoz

Melcoz has been packed with VMProtect and Themida.[59]

S0455 Metamorfo

Metamorfo has used VMProtect to pack and protect files.[60]

S0083 Misdat

Misdat was typically packed using UPX.[61]

S1026 Mongall

Mongall has been packed with Themida.[5]

G1019 MoustachedBouncer

MoustachedBouncer has used malware plugins packed with Themida.[62]


NETWIRE has used .NET packer tools to evade detection.[63]

C0002 Night Dragon

During Night Dragon, threat actors used software packing in its tools.[64]

S0264 OopsIE

OopsIE uses the SmartAssembly obfuscator to pack an embedded .Net Framework assembly used for C2.[65]

C0022 Operation Dream Job

During Operation Dream Job, Lazarus Group packed malicious .db files with Themida to evade detection.[35][66][67]

C0016 Operation Dust Storm

For Operation Dust Storm, the threat actors used UPX to pack some payloads.[61]

C0005 Operation Spalax

For Operation Spalax, the threat actors used a variety of packers, including CyaX, to obfuscate malicious executables.[68]


OSX_OCEANLOTUS.D has a variant that is packed with UPX.[69]

G0040 Patchwork

A Patchwork payload was packed with UPX.[70]

S0650 QakBot

QakBot can encrypt and pack malicious payloads.[71]

S0565 Raindrop

Raindrop used a custom packer for its Cobalt Strike payload, which was compressed using the LZMA algorithm.[72][73]

G0106 Rocke

Rocke's miner has created UPX-packed files in the Windows Start Menu Folder.[74][75][76]

S0085 S-Type

Some S-Type samples have been packed with UPX.[61]

S1018 Saint Bot

Saint Bot has been packed using a dark market crypter.[77]

S0461 SDBbot

SDBbot has used a packed installer file.[78]

S0053 SeaDuke

SeaDuke has been packed with the UPX packer.[79]

S0444 ShimRat

ShimRat's loader has been packed with the compressed ShimRat core DLL and the legitimate DLL for it to hijack.[80]

S0543 Spark

Spark has been packed with Enigma Protector to obfuscate its contents.[81]

S1030 Squirrelwaffle

Squirrelwaffle has been packed with a custom packer to hide payloads.[82][83]

S0663 SysUpdate

SysUpdate has been packed with VMProtect.[52][84]

G1018 TA2541

TA2541 has used a .NET packer to obfuscate malicious files.[85]

G0092 TA505

TA505 has used UPX to obscure malicious code.[78]

G0139 TeamTNT

TeamTNT has used UPX and Ezuri packer to pack its binaries.[86]

G0089 The White Company

The White Company has obfuscated their payloads through packing.[87]

G0027 Threat Group-3390

Threat Group-3390 has packed malware and tools, including using VMProtect.[88][52]

S0671 Tomiris

Tomiris has been packed with UPX.[89]

S0678 Torisma

Torisma has been packed with Iz4 compression.[67]

S0266 TrickBot

TrickBot leverages a custom packer to obfuscate its functionality.[90]

S0094 Trojan.Karagany

Trojan.Karagany samples sometimes use common binary packers such as UPX and Aspack on top of a custom Delphi binary packer.[91][92]

S0022 Uroburos

Uroburos uses a custom packer.[93][94]

S0476 Valak

Valak has used packed DLL payloads.[95]


VERMIN is initially packed.[96]

S0248 yty

yty packs a plugin with UPX.[97]

S0251 Zebrocy

Zebrocy's Delphi variant was packed with UPX.[98][99]

S0230 ZeroT

Some ZeroT DLL files have been packed with UPX.[100]


ZIRCONIUM has used multi-stage packers for exploit code.[101]


ID Mitigation Description
M1049 Antivirus/Antimalware

Employ heuristic-based malware detection. Ensure updated virus definitions and create custom signatures for observed malware.


ID Data Source Data Component Detects
DS0022 File File Metadata

Use file scanning to look for known software packers or artifacts of packing techniques. Packing is not a definitive indicator of malicious activity, because legitimate software may use packing techniques to reduce binary size or to protect proprietary code.


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