Microsoft warns organizations of consent phishing attacks

microsoft-warns-organizations-of-consent-phishing-attacks

In this type of phishing campaign, attackers trick people into giving a malicious app consent to access sensitive data, says Microsoft.

phishing

Image: weerapatkiatdumrong, Getty Images/iStockphoto

Phishing campaigns are a common tactic in which cybercriminals impersonate a well-known company, product, or brand to steal account credentials, financial information, or other data from unsuspecting victims. A typical phishing attack convinces the user to directly enter their password and login credentials, which are then captured by the attacker.

But a more specialized type of campaign known as consent phishing aims to grab sensitive data not by snagging your password but by tricking you into giving the necessary permissions to a malicious app. A Microsoft blog post published on Wednesday explains how it works.

SEE: Fighting social media phishing attacks: 10 tips (free PDF) (TechRepublic) 

This type of consent phishing relies on the OAuth 2.0 authorization technology. By implementing the OAuth protocol into an app or website, a developer gives a user the ability to grant permission to certain data without having to enter their password or other credentials.

Used by a variety of online companies including Microsoft, Google, and Facebook, OAuth is a way to try to simplify the login and authorization process for apps and websites through a single sign-on mechanism. However, as with many technologies, OAuth can be used for both beneficial and malicious purposes.

Microsoft details the problem step by step in its blog post:

  1. An attacker registers an app with an OAuth 2.0 provider, such as Azure Active Directory.
  2. The app is configured in a way that makes it seem trustworthy, such as using the name of a popular product used in the same ecosystem.
  3. The attacker gets a link in front of users, which may be done through conventional email-based phishing, by compromising a non-malicious website, or through other techniques.
  4. The user clicks the link and is shown an authentic consent prompt asking them to grant the malicious app permissions to data.
  5. If a user clicks Accept, they grant the app permissions to access sensitive data.
  6. The app gets an authorization code, which it redeems for an access token, and potentially a refresh token.
  7. The access token is used to make API calls on behalf of the user.
  8. The attacker can then gain access to the user’s mail, forwarding rules, files, contacts, notes, profile, and other sensitive data.

Consent screen from a sample malicious app named “Risky App.”

Image: Microsoft

Microsoft touted some of the steps it’s taken to try to prevent this type of malicious behavior. The company said it uses such security tools as identity and access management, device management, threat protection, and cloud security to analyze millions of data points to help detect malicious apps. Further, Microsoft is trying to better secure its application ecosystems by allowing customers to set policies on the types of apps to which users can give certain consent.

Despite the efforts of Microsoft and other companies, these attacks persist as cybercriminals stay one step ahead of the game. To help protect against consent phishing campaigns, Microsoft offers advice for individuals and organizations.

For individuals:

  • Check for poor spelling and grammar. If an email message or the application’s consent screen has spelling and grammatical errors, it’s likely to be a suspicious application.
  • Keep a watchful eye on app names and domain URLs. Attackers like to spoof app names that make it appear to come from legitimate applications or companies but drive you to consent to a malicious app. Make sure you recognize the app name and domain URL before consenting to an application.

For organizations:

Microsoft also advised concerned organizations to check its documentation on “Detect and Remediate Illicit Consent Grants” and “Five steps to securing your identity infrastructure.”

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