In most cases, trust boundaries are violated when a secret is exposed in a source code repository or an uncontrolled deployment environment.
Unintended people who don’t need to know the secret might get access to it. They might then be able to use it to gain unwanted access to associated
services or resources.
The trust issue can be more or less severe depending on the people’s role and entitlement.
What is the potential impact?
Teams Workflow webhook URLs have different effects depending on their permissions: They can be used only to write Teams posts or to trigger other
workflows.
Below are some real-world scenarios that illustrate some impacts of an attacker exploiting the secret.
Phishing and spam
An attacker can use this {secret_type} to spam users or lure them into links to a malicious domain controlled by the attacker.
Spam can cause users to be exposed to the following:
- Unsolicited, inappropriate content, such as pornographic material
- Fraudulent attempts to trick users into sending information or money
- Abusive or hateful statements
- False advertising or fraudulent claims
Once a user has been phished on a legitimate-seeming third-party website, an attacker can collect the user’s credentials, bypass multi-factor
authentication (MFA), and take over the user’s account on the trusted website.
Malware distribution
Due to this vulnerability, malware can be stored and spread, both to users of the service and to other potential targets.
A malware depends on
the attacker’s intentions, as the following examples show:
- Cryptojacking malware, whose goal is to "mine" cryptocurrencies on the affected computers or servers.
- Spyware that spies out sensitive information from victims.
In the worst case, malware can cause the target systems to be completely compromised and allow attackers to infiltrate the systems.
Chaining of vulnerabilities
Triggering arbitrary workflows can lead to problems ranging from a denial of service to worse, depending on how the webhook’s data is handled. If
the webhook performs a specific action that is affected by a vulnerability, the webhook acts as a remote attack vector on the enterprise.
Components affected by this webhook could, for example, experience unexpected failures or excessive resource consumption. If it is a single point
of failure (SPOF), this leak is critical.
