Emissary is a Trojan that has been used by Lotus Blossom. It shares code with Elise, with both Trojans being part of a malware group referred to as LStudio. [1]

ID: S0082
Platforms: Windows
Version: 1.2
Created: 31 May 2017
Last Modified: 09 August 2021

Techniques Used

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

Emissary uses HTTP or HTTPS for C2.[1]

Enterprise T1547 .001 Boot or Logon Autostart Execution: Registry Run Keys / Startup Folder

Variants of Emissary have added Run Registry keys to establish persistence.[2]

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

Emissary has the capability to create a remote shell and execute specified commands.[1]

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

Emissary is capable of configuring itself as a service.[2]

Enterprise T1573 .001 Encrypted Channel: Symmetric Cryptography

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.[1]

Enterprise T1615 Group Policy Discovery

Emissary has the capability to execute gpresult.[2]

Enterprise T1105 Ingress Tool Transfer

Emissary has the capability to download files from the C2 server.[1]

Enterprise T1027 Obfuscated Files or Information

Variants of Emissary encrypt payloads using various XOR ciphers, as well as a custom algorithm that uses the "srand" and "rand" functions.[1][2]

.001 Binary Padding

A variant of Emissary appends junk data to the end of its DLL file to create a large file that may exceed the maximum size that anti-virus programs can scan.[2]

Enterprise T1069 .001 Permission Groups Discovery: Local Groups

Emissary has the capability to execute the command net localgroup administrators.[2]

Enterprise T1055 .001 Process Injection: Dynamic-link Library Injection

Emissary injects its DLL file into a newly spawned Internet Explorer process.[1]

Enterprise T1218 .011 System Binary Proxy Execution: Rundll32

Variants of Emissary have used rundll32.exe in Registry values added to establish persistence.[2]

Enterprise T1082 System Information Discovery

Emissary has the capability to execute ver and systeminfo commands.[2]

Enterprise T1016 System Network Configuration Discovery

Emissary has the capability to execute the command ipconfig /all.[2]

Enterprise T1007 System Service Discovery

Emissary has the capability to execute the command net start to interact with services.[2]

Groups That Use This Software

ID Name References
G0030 Lotus Blossom