• Home
  • Cyber Crime
  • Cyber warfare
  • APT
  • Data Breach
  • Deep Web
  • Digital ID
  • Hacking
  • Hacktivism
  • Intelligence
  • Internet of Things
  • Laws and regulations
  • Malware
  • Mobile
  • Reports
  • Security
  • Social Networks
  • Terrorism
  • ICS-SCADA
  • POLICIES
  • Contact me
MUST READ

Healthcare Services Group discloses 2024 data breach that impacted 624,496 people

 | 

ESET warns of PromptLock, the first AI-driven ransomware

 | 

China linked Silk Typhoon targeted diplomats by hijacking web traffic

 | 

Farmers Insurance discloses a data breach impacting 1.1M customers

 | 

Citrix fixed three NetScaler flaws, one of them actively exploited in the wild

 | 

Auchan discloses data breach: data of hundreds of thousands of customers exposed

 | 

U.S. CISA adds Citrix Session Recording, and Git flaws to its Known Exploited Vulnerabilities catalog

 | 

Docker fixes critical Desktop flaw allowing container escapes

 | 

Malicious apps with +19M installs removed from Google Play because spreading Anatsa banking trojan and other malware

 | 

Pakistan-linked APT36 abuses Linux .desktop files to drop custom malware in new campaign

 | 

Android.Backdoor.916.origin malware targets Russian business executives

 | 

Electronics manufacturer Data I/O took offline operational systems following a ransomware attack

 | 

IoT under siege: The return of the Mirai-based Gayfemboy Botnet

 | 

SECURITY AFFAIRS MALWARE NEWSLETTER ROUND 59

 | 

Security Affairs newsletter Round 538 by Pierluigi Paganini – INTERNATIONAL EDITION

 | 

Kidney dialysis firm DaVita confirms ransomware attack compromised data of 2.7M people

 | 

China-linked Silk Typhoon APT targets North America

 | 

Over 300 entities hit by a variant of Atomic macOS Stealer in recent campaign

 | 

Operation Serengeti 2.0: INTERPOL nabs 1,209 cybercriminals in Africa, seizes $97M

 | 

After SharePoint attacks, Microsoft stops sharing PoC exploit code with China

 | 
  • Home
  • Cyber Crime
  • Cyber warfare
  • APT
  • Data Breach
  • Deep Web
  • Digital ID
  • Hacking
  • Hacktivism
  • Intelligence
  • Internet of Things
  • Laws and regulations
  • Malware
  • Mobile
  • Reports
  • Security
  • Social Networks
  • Terrorism
  • ICS-SCADA
  • POLICIES
  • Contact me
  • Home
  • Breaking News
  • Hacking
  • A flaw in Microsoft OAuth authentication could lead Azure account takeover

A flaw in Microsoft OAuth authentication could lead Azure account takeover

Pierluigi Paganini December 03, 2019

A vulnerability in the Microsoft OAuth implementation exposes Azure cloud accounts to takeover.

The vulnerability affects the way Microsoft applications use OAuth for authentication, these applications trust certain third-party domains and sub-domains that are not registered by Microsoft.

Experts from Cyberark discovered the following three vulnerable Microsoft applications that trust these unregistered domains Portfolios, O365 Secure Score, Microsoft Service Trust.

“This vulnerability’s attack surface is very wide and its impact can be very powerful.” reads the analysis published by CyberArk “By doing nothing more than clicking or visiting a website, the victim can experience the theft of sensitive data, compromised production servers, lost data, manipulation of data, encryption of all the organization’s data with ransomware and more.”

In the OAuth authorization flow implemented by Microsoft, a Microsoft application user can request access from a whitelisted URL approved by Microsoft to login.

The owner of the third-party website or application will receive a token with specific permissions that allows it to act on behalf of the owner of the token.

The experts noticed that some URLs whitelisted by Microsoft are not previously registered with the Azure portal. The researchers noticed that the web API URLs that are “trusted” by Microsoft native apps end with “.cloudapp.net,” “.azurewebsites.net” and .{vm_region}.cloudapp.azure.com, but they noticed that at least 54 sub-domains with these characteristics were not registered in the Azure portal.

The attackers could take over these domains and then registering them, in this way they would be approved by default and could request users’  “access_tokens” and act on behalf of the user with its permissions.

“Attackers requesting a token on behalf of a privileged user for “https://graph.windows.net” with “user_impersonation” privileges – default privileges every application gets, if not defined otherwise – can perform requests to API  endpoints, including resetting passwords for other users in the AD, adding members to a directory role or adding users to groups (depending on the victim’s privileges).  You can see more API calls documented here.” continues the analysis.
“This vulnerability makes it much easier to compromise privilege users – whether through simple social engineering techniques or by infecting a website that the privileged users occasionally access.”

The experts published a proof of concept (PoC) of the attack that shows how an attacker could create a crafted link for the Microsoft OAuth authentication process. The researchers composed the link using three parameters: The application_id parameter that must match the vulnerable OAuth application, the redirect_uri parameter that must be white-listed domains, and the resource parameter that must be the desired resource that an attacker wants to get access to on behalf of the user.

An attacker could embed an iframe tag into a website with the “src” attribute set to the crafted link, then trick the victim into visiting it. Once the victim visits the website, the victim’s browser will render the iframe and microsoftonline[.]com redirects the victim to the attacker’s domain and automatically grants the access token.

The attackers install in the domain a Javascript that sends API requests using the stolen access token.

Below the vulnerability timeline:

  • 29/10/19 – The vulnerability found
  • 30/10/19 – Vulnerability reported to Microsoft
  • 31/10/19 – Report was closed by Microsoft – ?!?
  • 07/11/19 – Vulnerability reported again to Microsoft
  • 08/11/19 – Case opened
  • 12/11/19 – Microsoft contacted me for more information
  • 20/11/19 – Vulnerability fixed

“While OAuth 2.0 is an excellent solution for authorization, if misused or misconfigured, it could have a tremendous impact, allowing for over-privileged third-party applications or the eventual account takeover by malicious attackers.” concludes the report.

“To mitigate risk and prevent these vulnerabilities, you can do the following:

  1. Make sure that all the trusted redirect URIs configured in the application are under your ownership.
  2. Remove unnecessary redirect URIs.
  3. Make sure the permissions that the OAuth application asks for are the least privileged one it needs.
  4. Disable non-used applications.”
[adrotate banner=”9″] [adrotate banner=”12″]

Pierluigi Paganini

(SecurityAffairs – OAuth, hacking)

[adrotate banner=”5″]

[adrotate banner=”13″]


facebook linkedin twitter

authentication Hacking hacking news Microsoft Pierluigi Paganini Security Affairs Security News

you might also like

Pierluigi Paganini August 27, 2025
Healthcare Services Group discloses 2024 data breach that impacted 624,496 people
Read more
Pierluigi Paganini August 27, 2025
ESET warns of PromptLock, the first AI-driven ransomware
Read more

leave a comment

newsletter

Subscribe to my email list and stay
up-to-date!

    recent articles

    Healthcare Services Group discloses 2024 data breach that impacted 624,496 people

    Data Breach / August 27, 2025

    ESET warns of PromptLock, the first AI-driven ransomware

    Malware / August 27, 2025

    China linked Silk Typhoon targeted diplomats by hijacking web traffic

    Security / August 27, 2025

    Farmers Insurance discloses a data breach impacting 1.1M customers

    Data Breach / August 26, 2025

    Citrix fixed three NetScaler flaws, one of them actively exploited in the wild

    Hacking / August 26, 2025

    To contact me write an email to:

    Pierluigi Paganini :
    pierluigi.paganini@securityaffairs.co

    LEARN MORE

    QUICK LINKS

    • Home
    • Cyber Crime
    • Cyber warfare
    • APT
    • Data Breach
    • Deep Web
    • Digital ID
    • Hacking
    • Hacktivism
    • Intelligence
    • Internet of Things
    • Laws and regulations
    • Malware
    • Mobile
    • Reports
    • Security
    • Social Networks
    • Terrorism
    • ICS-SCADA
    • POLICIES
    • Contact me

    Copyright@securityaffairs 2024

    We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. By clicking “Accept All”, you consent to the use of ALL the cookies. However, you may visit "Cookie Settings" to provide a controlled consent.
    Cookie SettingsAccept All
    Manage consent

    Privacy Overview

    This website uses cookies to improve your experience while you navigate through the website. Out of these cookies, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities...
    Necessary
    Always Enabled
    Necessary cookies are absolutely essential for the website to function properly. This category only includes cookies that ensures basic functionalities and security features of the website. These cookies do not store any personal information.
    Non-necessary
    Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. It is mandatory to procure user consent prior to running these cookies on your website.
    SAVE & ACCEPT