type: attack-pattern
spec_version: 2.1
id: attack-pattern--01df3350-ce05-4bdf-bdf8-0a919a66d4a8
created: 2017-12-14T16:46:06.044Z
created_by_ref: identity--c78cb6e5-0c4b-4611-8297-d1b8b55e40b5
revoked: yes
external_references: source_name: mitre-attack
url: https://attack.mitre.org/techniques/T1156
external_id: T1156
source_name: intezer-kaiji-malware
description: Paul Litvak. (2020, May 4). Kaiji: New Chinese Linux malware turning to Golang. Retrieved December 17, 2020.
url: https://www.intezer.com/blog/research/kaiji-new-chinese-linux-malware-turning-to-golang/
object_marking_refs: marking-definition--fa42a846-8d90-4e51-bc29-71d5b4802168
modified: 2025-10-24T17:48:19.775Z
name: Malicious Shell Modification
description: Adversaries may establish persistence through executing malicious commands triggered by a user’s shell. User shells execute several configuration scripts at different points throughout the session based on events. For example, when a user opens a command line interface or remotely logs in (such as SSH) a login shell is initiated. The login shell executes scripts from the system (/etc) and the user’s home directory (~/) to configure the environment. All login shells on a system use /etc/profile when initiated. These configuration scripts run at the permission level of their directory and are often used to set environment variables, create aliases, and customize the user’s environment. When the shell exits or terminates, additional shell scripts are executed to ensure the shell exits appropriately. 

Adversaries may attempt to establish persistence by inserting commands into scripts automatically executed by shells. Using bash as an example, the default shell for most GNU/Linux systems, adversaries may add commands that launch malicious binaries into the /etc/profile and /etc/profile.d files (Citation: intezer-kaiji-malware). These files require root permissions and are executed each time any shell on a system launches. For user level permissions, adversaries can insert malicious commands into ~/.bash_profile, ~/.bash_login, or ~/.profile (Rocke) which are sourced when a user opens a command line interface or connects remotely. Adversaries often use ~/.bash_profile since the system only executes the first file that exists in the listed order. Adversaries have also leveraged the ~/.bashrc file (Tsunami, Rocke, Linux Rabbit, Magento) which is additionally executed if the connection is established remotely or an additional interactive shell is opened, such as a new tab in the command line interface. Some malware targets the termination of a program to trigger execution (Cannon), adversaries can use the ~/.bash_logout file to execute malicious commands at the end of a session(Pearl_shellbot). 

For macOS, the functionality of this technique is similar but leverages zsh, the default shell for macOS 10.15+. When the Terminal.app is opened, the application launches a zsh login shell and a zsh interactive shell. The login shell configures the system environment using /etc/profile, /etc/zshenv, /etc/zprofile, and /etc/zlogin. The login shell then configures the user environment with ~/.zprofile and ~/.zlogin. The interactive shell uses the ~/.zshrc to configure the user environment. Upon exiting, /etc/zlogout and ~/.zlogout are executed. For legacy programs, macOS executes /etc/bashrc on startup.
kill_chain_phases: kill_chain_name: mitre-attack
phase_name: persistence
x_mitre_attack_spec_version: 3.2.0
x_mitre_contributors: Robert Wilson
Joe Gervais
Tony Lambert, Red Canary
x_mitre_deprecated: no
x_mitre_domains: enterprise-attack
x_mitre_is_subtechnique: no
x_mitre_modified_by_ref: identity--c78cb6e5-0c4b-4611-8297-d1b8b55e40b5
x_mitre_platforms: Linux
macOS
x_mitre_version: 1.2