Web Cookies
Where this stands
One published detection covers this technique. Every one is unverified — no rule on Siemphony has been executed against real telemetry.
What the technique is
Adversaries may forge web cookies that can be used to gain access to web applications or Internet services. Web applications and services (hosted in cloud SaaS environments or on-premise servers) often use session cookies to authenticate and authorize user access. Adversaries may generate these cookies in order to gain access to web resources. This differs from Steal Web Session Cookie and other similar behaviors in that the cookies are new and forged by the adversary, rather than stolen or intercepted from legitimate users. Most common web applications have standardized and documented cookie values that can be generated using provided tools or interfaces. The generation of web cookies often requires secret values, such as passwords, Private Keys, or other cryptographic seed values. Once forged, adversaries may use these web cookies to access resources (Web Session Cookie), which may bypass multi-factor and other authentication protection mechanisms.
Read it on attack.mitre.orgWhat MITRE says you would watch
- AN0483
Forged cookies in IaaS environments may appear as authentication attempts that bypass MFA, leveraging AssumeRole or session APIs with cookies that were never legitimately issued. Defenders should correlate cloud logs for cookie-based sessions without prior valid authentication, often followed by resource access from unfamiliar IP addresses.
- AN0484
Forged web cookies on Windows endpoints can be detected by monitoring unusual modifications of browser cookie stores (e.g., Chrome SQLite DB, Edge cache) by processes outside of browsers, followed by authentication events to SaaS or IaaS services. Defenders may observe processes writing directly to cookie storage paths or injecting tokens into browser sessions.
- AN0485
On Linux, defenders may observe forged cookie activity as unauthorized modifications to browser cookie databases (e.g., ~/.mozilla/firefox/*/cookies.sqlite, ~/.config/chromium/Default/Cookies) or scripted injection of session tokens. Suspicious usage includes curl/wget commands embedding forged cookies in headers, correlated with abnormal session activity in SaaS or IaaS logs.
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