ZLib is a full-featured backdoor that was used as a second-stage implant during Operation Dust Storm since at least 2014. ZLib is malware and should not be confused with the legitimate compression library from which its name is derived.[1]

ID: S0086
Platforms: Windows
Version: 1.2
Created: 31 May 2017
Last Modified: 30 September 2022

Techniques Used

Domain ID Name Use
Enterprise T1071 .001 Application Layer Protocol: Web Protocols

ZLib communicates over HTTP for C2.[1]

Enterprise T1560 .002 Archive Collected Data: Archive via Library

The ZLib backdoor compresses communications using the standard Zlib compression library.[1]

Enterprise T1059 .003 Command and Scripting Interpreter: Windows Command Shell

ZLib has the ability to execute shell commands.[1]

Enterprise T1543 .003 Create or Modify System Process: Windows Service

ZLib creates Registry keys to allow itself to run as various services.[1]

Enterprise T1041 Exfiltration Over C2 Channel

ZLib has sent data and files from a compromised host to its C2 servers.[1]

Enterprise T1083 File and Directory Discovery

ZLib has the ability to enumerate files and drives.[1]

Enterprise T1105 Ingress Tool Transfer

ZLib has the ability to download files.[1]

Enterprise T1036 .005 Masquerading: Match Legitimate Name or Location

ZLib mimics the resource version information of legitimate Realtek Semiconductor, Nvidia, or Synaptics modules.[1]

Enterprise T1113 Screen Capture

ZLib has the ability to obtain screenshots of the compromised system.[1]

Enterprise T1082 System Information Discovery

ZLib has the ability to enumerate system information.[1]

Enterprise T1007 System Service Discovery

ZLib has the ability to discover and manipulate Windows services.[1]


ID Name Description
C0016 Operation Dust Storm