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Ebury is an SSH backdoor targeting Linux operating systems. Attackers require root-level access, which allows them to replace SSH binaries (ssh, sshd, ssh-add, etc) or modify a shared library used by OpenSSH (libkeyutils).[1][2]

ID: S0377
Platforms: Linux
Contributors: Marc-Etienne M.Léveillé, ESET
Version: 1.0
Created: 19 April 2019
Last Modified: 26 April 2019

Techniques Used

Domain ID Name Use
Enterprise T1116 Code Signing

Ebury has installed a self-signed RPM package mimicking the original system package on RPM based systems.[1]

Enterprise T1043 Commonly Used Port

Ebury has used UDP port 53 for C2. [1]

Enterprise T1024 Custom Cryptographic Protocol

Ebury has encrypted C2 traffic using the client IP address, then encoded it as a hexadecimal string.[1]

Enterprise T1132 Data Encoding

Ebury has encoded C2 traffic. [1]

Enterprise T1089 Disabling Security Tools

Ebury has disabled logging when the backdoor is used. [1]

Enterprise T1483 Domain Generation Algorithms

Ebury has used a DGA to generate a domain name for C2.[1]

Enterprise T1027 Obfuscated Files or Information

Ebury has obfuscated its strings with a simple XOR encryption with a static key.[1]

Enterprise T1145 Private Keys

Ebury has intercepted unencrypted private keys as well as private key pass-phrases. [1]

Enterprise T1184 SSH Hijacking

Ebury has hijacked the OpenSSH process by injecting into the existing session as opposed to creating a new session.[1]

Enterprise T1071 Standard Application Layer Protocol

Ebury has used DNS requests over UDP port 53. [1]