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.
After acquiring credentials from web browsers, adversaries may attempt to recycle the credentials across different systems and/or accounts in order to expand access. This can result in significantly furthering an adversary's objective in cases where credentials gained from web browsers overlap with privileged accounts (e.g. domain administrator).
|G0130||Ajax Security Team|
Kimsuky has used browser extensions including Google Chrome to steal passwords and cookies from browsers. Kimsuky has also used Nirsoft's WebBrowserPassView tool to dump the passwords obtained from victims.
Mimikatz performs credential dumping to obtain account and password information useful in gaining access to additional systems and enterprise network resources. It contains functionality to acquire information about credentials in many ways, including from DPAPI.
OilRig has used credential dumping tools such as LaZagne to steal credentials to accounts logged into the compromised system and to Outlook Web Access. OilRig has also used tool named PICKPOCKET to dump passwords from web browsers.
PinchDuke steals credentials from compromised hosts. PinchDuke's credential stealing functionality is believed to be based on the source code of the Pinch credential stealing malware (also known as LdPinch). Credentials targeted by PinchDuke include ones associated with many sources such as Netscape Navigator, Mozilla Firefox, Mozilla Thunderbird, and Internet Explorer. 
Organizations may consider weighing the risk of storing credentials in web browsers. If web browser credential disclosure is a significant concern, technical controls, policy, and user training may be used to prevent storage of credentials in web browsers.
|ID||Data Source||Data Component||Detects|
Monitor executed commands and arguments that may acquire credentials from web browsers by reading files specific to the target browser.
Identify web browser files that contain credentials such as Google Chrome’s Login Data database file:
|DS0009||Process||OS API Execution||
Monitor for API calls that may acquire credentials from web browsers by reading files specific to the target browser.
Monitor process execution logs to include PowerShell Transcription focusing on those that perform a combination of behaviors including reading web browser process memory, utilizing regular expressions, and those that contain numerous keywords for common web applications (Gmail, Twitter, Office365, etc.).