T1606No distinct observable

Forge Web Credentials

Credential AccessSaaS, Windows, macOS, Linux, IaaS, Office Suite, Identity Provider

Where this stands

A reviewer read the telemetry and concluded there is nothing here to detect that a sibling technique does not already cover.

The technique is defined by the credential being new and forged — its own description contrasts it explicitly with T1539 and T1528, where the credential is stolen — and nothing in this brief can observe newness. AN0719 offers Sysmon EID 10 process_access and Security 4624/4648: a process opening lsass.exe or a browser process is credential theft (T1003.001, T1555.003/T1539), and tagging that attack.t1606 is precisely the mislabelling AUTHORING.md rule 3 forbids, while 4624/4648 record a Windows logon, which a forged web cookie or SAML assertion presented to a SaaS endpoint never produces on any host. […]

Covered instead by T1606.001, T1606.002, T1539, T1003.001.

What the technique is

Adversaries may forge credential materials 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, tokens, or other materials to authenticate and authorize user access. Adversaries may generate these credential materials in order to gain access to web resources. This differs from Steal Web Session Cookie, Steal Application Access Token, and other similar behaviors in that the credentials are new and forged by the adversary, rather than stolen or intercepted from legitimate users. The generation of web credentials often requires secret values, such as passwords, Private Keys, or other cryptographic seed values. Adversaries may also forge tokens by taking advantage of features such as the AssumeRole and GetFederationToken APIs in AWS, which allow users to request temporary security credentials (i.e., Temporary Elevated Cloud Access), or the zmprov gdpak command in Zimbra, which generates a pre-authentication key that can be used to generate tokens for any user in the domain. Once forged, adversaries may use these web credentials to access resources (ex: Use Alternate Authentication Material), which may bypass multi-factor and other authentication protection mechanisms.

Read it on attack.mitre.org

What MITRE says you would watch

AN0717
Defenders may detect adversaries forging web credentials in IaaS environments by monitoring for anomalous API activity such as AssumeRole or GetFederationToken being executed by unusual principals. These events often correlate with sudden logon sessions from unfamiliar IP addresses or regions. The chain is usually secret material misuse (stolen private key or password) → API request generating a new token → access to high-value resources.
AN0718
Forged web credentials may manifest as anomalous SAML token issuance, OpenID Connect token minting, or Zimbra pre-auth key usage. Defenders may see tokens issued without normal authentication events, multiple valid tokens generated simultaneously, or signing anomalies in IdP logs.
AN0719
Forged web credentials on Windows endpoints may be detected by anomalous browser cookie files, local token cache manipulations, or tools injecting tokens into sessions. Defenders may observe processes accessing LSASS or browser credential stores unexpectedly, followed by unusual logon sessions.