Credentials from Web Browsers

What the technique is

Adversaries may acquire credentials from web browsers by reading files specific to the target browser. Web browsers commonly save credentials such as website usernames and passwords so that they do not need to be entered manually in the future. Web browsers typically store the credentials in an encrypted format within a credential store; however, methods exist to extract plaintext credentials from web browsers. For example, on Windows systems, encrypted credentials may be obtained from Google Chrome by reading a database file, AppData\Local\Google\Chrome\User Data\Default\Login Data and executing a SQL query: SELECT action_url, username_value, password_value FROM logins;. The plaintext password can then be obtained by passing the encrypted credentials to the Windows API function CryptUnprotectData, which uses the victim’s cached logon credentials as the decryption key. Adversaries have executed similar procedures for common web browsers such as FireFox, Safari, Edge, etc. Windows stores Internet Explorer and Microsoft Edge credentials in Credential Lockers managed by the Windows Credential Manager. Adversaries may also acquire credentials by searching web browser process memory for patterns that commonly match credentials. […]

What MITRE says you would watch

• AN0105

  Detects unauthorized access to web browser credential stores (e.g., Chrome Login Data, Edge Credential Locker) by processes other than the browser itself. Correlates file reads of credential databases with subsequent API calls to CryptUnprotectData or memory inspection attempts.

• AN0106

  Detects attempts to access browser credential stores (e.g., Firefox logins.json, Chrome SQLite DB) or processes (e.g., gnome-keyring-daemon). Observes unauthorized file reads and memory inspection of browser processes using ptrace or gdb.

• AN0107

  Detects abnormal access to Safari credential stores (Keychain-backed) or Chrome/Firefox login databases. Observes processes executing security dump-keychain or directly reading credential files in ~/Library/Application Support. Correlates file access with suspicious process ancestry or unsigned binaries.