Malicious Copy and Paste

What the technique is

An adversary may rely upon a user copying and pasting code in order to gain execution. Users may be subjected to social engineering to get them to copy and paste code directly into a Command and Scripting Interpreter. One such strategy is "ClickFix," in which adversaries present users with seemingly helpful solutions—such as prompts to fix errors or complete CAPTCHAs—that instead instruct the user to copy and paste malicious code. Malicious websites, such as those used in Drive-by Compromise, may present fake error messages or CAPTCHA prompts that instruct users to open a terminal or the Windows Run Dialog box and execute an arbitrary command. These commands may be obfuscated using encoding or other techniques to conceal malicious intent. Once executed, the adversary will typically be able to establish a foothold on the victim's machine. Adversaries may also leverage phishing emails for this purpose. When a user attempts to open an attachment, they may be presented with a fake error and offered a malicious command to paste as a solution, consistent with the "ClickFix" strategy. Tricking a user into executing a command themselves may help to bypass email filtering, browser sandboxing, or other mitigations designed to protect users against malicious downloaded files.

What MITRE says you would watch

• AN0962

  A user is socially engineered (web page, email, document) to open Run/PowerShell/CMD and paste an obfuscated one-liner. The chain is: (1) user context active in a browser/email/office app → (2) process creation of a command interpreter with suspicious arguments (base64/Invoke-Expression/web download/pipeline to shell) → (3) optional file drop in %TEMP% or %APPDATA% → (4) outbound network connection to an external domain. Events are correlated within a short window and with consistent user/session.

• AN0963

  User pastes a multi-line or one-liner into a terminal (bash/zsh) that downloads/decodes and executes content. Chain: terminal exec of curl/wget/bash/sh with pipe to interpreter or base64-decode → transient file under /tmp|~/.cache → immediate outbound egress.

• AN0964

  User pastes an obfuscated command into Terminal.app/iTerm2 that decodes or downloads code and executes. Detects Terminal/iTerm2 spawning bash/zsh/python with suspicious pipeline/base64 patterns followed by file writes in ~/Library or /tmp and outbound network connections.