T1539
Steal Web Session Cookie
Linux · macOS · Office Suite · SaaS · Windows1 piece on this siteT1539 on attack.mitre.org
An adversary may steal web application or service session cookies and use them to gain access to web applications or Internet services as an authenticated user without needing credentials. Web applications and services often use session cookies as an authentication token after a user has authenticated to a website. Cookies are often valid for an extended period of time, even if the web application is not actively used.
If this is happening now
Checklists and playbooks to open while the alert is still live.
Cloud account takeover response plan: sessions, methods, devices and grants, then what they read
A successful sign-in the user did not make, in Microsoft Entra ID and Microsoft 365. A password reset alone evicts almost nobody. The plan works through the order that does, how to tell a guessed password from a stolen session, and how to answer what they read.
how MITRE says to see it
Detection of Web Session Cookie Theft via File, Memory, and Network Artifacts
- Detects suspicious access to browser session cookie storage (e.g., Chrome’s `Cookies` SQLite DB) or memory reads of browser processes. Anomalous injection or memory dump utilities targeting browser processes such as `chrome.exe`, `firefox.exe`, or `msedge.exe`.
- Detects access to known browser cookie files (e.g., `~/.mozilla/firefox/*.default/cookies.sqlite`, `~/.config/google-chrome/`) and suspicious reads of browser memory via `/proc/[pid]/mem` or ptrace.
- Detects unauthorized access to browser cookie paths (e.g., `~/Library/Application Support/Google/Chrome/Default/Cookies`) or `task_for_pid`/`vm_read` calls to Safari/Chrome memory space.
- Detects automation macros or VBA scripts in documents that access browser file paths, read cookie data, or attempt to exfiltrate browser session tokens over HTTP.
what reduces it
- M1021 Restrict Web-Based Content. Restrict or block web-based content that could be used to extract session cookies or credentials stored in browsers. Use browser security settings, such as disabling third-party cookies and restricting browser extensions, to limit the attack surface.
- M1017 User Training. Train users to identify aspects of phishing attempts where they're asked to enter credentials into a site that has the incorrect domain for the application they are logging into. Additionally, train users not to run untrusted JavaScript in their browser, such as by copying and pasting code or dragging and dropping bookmarklets.
- M1032 Multi-factor Authentication. Deploy hardware-based token (e.g., YubiKey or FIDO key), which incorporates the target login domain as part of the negotiation protocol, will prevent session cookie theft through proxy methods. Implement Conditional Access policies to only allow logins from trusted devices, such as those enrolled in Intune or joined via Hybrid/Entra.
- M1054 Software Configuration. Configure browsers or tasks to regularly delete persistent cookies. Additionally, minimize the length of time a web cookie is viable to potentially reduce the impact of stolen cookies while also increasing the needed frequency of cookie theft attempts – providing defenders with additional chances at detection.
- M1047 Audit. Implement auditing for authentication activities and user logins to detect the use of stolen session cookies. Monitor for impossible travel scenarios and anomalous behavior that could indicate the use of compromised session tokens or cookies.
- M1051 Update Software. Regularly update web browsers, password managers, and all related software to the latest versions. Keeping software up-to-date reduces the risk of vulnerabilities being exploited by attackers to extract stored credentials or session cookies.