Archive Collected Data: Archive via Library

An adversary may compress or encrypt data that is collected prior to exfiltration using 3rd party libraries. Many libraries exist that can archive data, including Python rarfile [1], libzip [2], and zlib [3]. Most libraries include functionality to encrypt and/or compress data.

Some archival libraries are preinstalled on systems, such as bzip2 on macOS and Linux, and zip on Windows. Note that the libraries are different from the utilities. The libraries can be linked against when compiling, while the utilities require spawning a subshell, or a similar execution mechanism.

ID: T1560.002
Sub-technique of:  T1560
Tactic: Collection
Platforms: Linux, Windows, macOS
Version: 1.0
Created: 20 February 2020
Last Modified: 29 March 2020

Procedure Examples

ID Name Description

BADFLICK has compressed data using the aPLib compression library.[4]


BBSRAT can compress data with ZLIB prior to sending it back to the C2 server.[5]

S0348 Cardinal RAT

Cardinal RAT applies compression to C2 traffic using the ZLIB library.[6]

S0354 Denis

Denis compressed collected data using zlib.[7]

S0091 Epic

Epic compresses the collected data with bzip2 before sending it to the C2 server.[8]

S0661 FoggyWeb

FoggyWeb can invoke the Common.Compress method to compress data with the C# GZipStream compression class.[9]

S1044 FunnyDream

FunnyDream has compressed collected files with zLib.[10]

S0260 InvisiMole

InvisiMole can use zlib to compress and decompress data.[11][12]

G0032 Lazarus Group

Lazarus Group malware IndiaIndia saves information gathered about the victim to a file that is compressed with Zlib, encrypted, and uploaded to a C2 server.[13][14]


OSX_OCEANLOTUS.D scrambles and encrypts data using AES256 before sending it to the C2 server.[15][16]

S0053 SeaDuke

SeaDuke compressed data with zlib prior to sending it over C2.[17]

S0467 TajMahal

TajMahal has the ability to use the open source libraries XZip/Xunzip and zlib to compress files.[18]

G0027 Threat Group-3390

Threat Group-3390 has used RAR to compress, encrypt, and password-protect files prior to exfiltration.[19]

S0086 ZLib

The ZLib backdoor compresses communications using the standard Zlib compression library.[20]


This type of attack technique cannot be easily mitigated with preventive controls since it is based on the abuse of system features.


ID Data Source Data Component Detects
DS0022 File File Creation

Monitor newly constructed files being written with extensions and/or headers associated with compressed or encrypted file types. Detection efforts may focus on follow-on exfiltration activity, where compressed or encrypted files can be detected in transit with a network intrusion detection or data loss prevention system analyzing file headers.

DS0012 Script Script Execution

Monitor for any attempts to enable scripts running on a system would be considered suspicious. If scripts are not commonly used on a system, but enabled, scripts running out of cycle from patching or other administrator functions are suspicious. Scripts should be captured from the file system when possible to determine their actions and intent.