TwoFace

Description

According to Unit42, TwoFace is a two-staged (loader+payload) webshell, written in C# and meant to run on webservers with ASP.NET. The author of the initial loader webshell included legitimate and expected content that will be displayed if a visitor accesses the shell in a browser, likely to remain undetected. The code in the loader webshell includes obfuscated variable names and the embedded payload is encoded and encrypted. To interact with the loader webshell, the threat actor uses HTTP POST requests to the compromised server.

The secondary webshell, which we call the payload, is embedded within the loader in encrypted form and contains additional functionality that we will discuss in further detail. When the threat actor wants to interact with the remote server, they provide data that the loader will use to modify a decryption key embedded within the loader that will be in turn used to decrypt the embedded TwoFace payload. Commands supported by the payload are execution of programs, up-, download and deletion of files and capability to manipulate MAC timestamps.

Names

Name
TwoFace
Minion
HighShell
HyperShell
SEASHARPEE

Category

Malware

Type

  • Backdoor
  • Info stealer
  • Exfiltration

Information

Mitre Attack

Malpedia

Other Information

Uuid

f02989df-45bc-4162-ba5b-8617795ee749

Last Card Change

2020-05-13