Endpoint

5/4/2017
11:30 AM
Greg Martin
Greg Martin
Commentary
Connect Directly
Twitter
LinkedIn
Twitter
LinkedIn
RSS
E-Mail vvv
50%
50%

Why OAuth Phishing Poses A New Threat to Users

Credential phishing lets attackers gain back-end access to email accounts, and yesterday's Google Docs scam raises the risk to a new level.

It's no secret that phishing attacks pose a constant threat to businesses. But a new tactic, recently seen in the cyber espionage campaign targeting Emmanuel Macron's presidential campaign in France and the Google Docs phishing scam circulating on the web on May 3, raise this threat to a new level.

A recent report by Trend Micro found the group behind many of the attacks (known as Pawn Storm, Fancy Bear, or APT28) was using an innovative type of credential phishing technique that takes advantage of the Open Authentication (OAuth) standard to gain back-end access to user email accounts. In its various campaigns, the group has used a number of fake add-on offers (such as for Google Defender, Google Scanner, and McAfee Email Protection) for popular email services including Gmail and Yahoo, in order to trick users into granting persistent access to their accounts. In the May 3 attack, hackers created a fake Google Doc app that exploits this same vulnerability.

This is a significant improvement in the traditional phishing lure. Because "OAuth phishing" avoids the typical red flags users have grown accustomed to with email phishing (that is, unfamiliar or spoofed URL link, sign-in request, or attached file), it is likely to have a higher rate of success and may even confound more experienced and competent users, such as upper management and those who have undergone security awareness training.

Misplaced Trust
OAuth phishing exploits the trust relationship users have with well-known online service providers, as well as the trust relationship those providers have with their own third-party applications. By sending the target an OAuth permission request for an approved application, the attacker is able to bypass all of the traditional warning signs users have been trained to look for when opening emails. Therefore, the email redirects the user to a legitimate Web domain (example: accounts.google.com) that is hosted over an encrypted HTTPS connection. Additionally, there is no need for the user to enter a password because the app is using OAuth tokens instead.

Everything about this will look aboveboard to a person who doesn't have a background in security. Making matters worse, the attacker is able to maintain access to the user's email account even after multiple password resets, because the only way to expel him is to revoke access within the user's account settings.

There have been limited instances of OAuth phishing in the wild, outside of the Pawn Storm campaigns. However, this week’s Google Doc scam is a sign of things to come. Now that this advanced technique is becoming more widely understood, it is reasonable to assume that this tactic will be adopted by many other threat actors, because of the many advantages it offers the attacker.

[Check out the two-day Dark Reading Cybersecurity Crash Course at Interop ITX, May 15 & 16, where Dark Reading editors and some of the industry's top cybersecurity experts will share the latest data security trends and best practices.

For instance, one can quickly see how this technique would benefit those criminal groups behind the many "business email compromise" scams now underway, to say nothing of corporate IP theft, government monitoring of human rights groups, social media scams, identity theft, celebrity targeting, and so on. It's also possible attackers could deliver these rogue applications via "watering hole" sites (blog posts, reviews, news media) instead of email, particularly if the app provides some legitimate function.

Although online service providers can help to curtail this threat by adding tougher standards to their approval processes for third-party applications, businesses and security professionals can't depend on an improved vetting process to entirely eliminate this new risk. Given the complexity of vetting third-party applications (After all, malicious mobile apps continue to find their way into official app stores, despite roughly nine years of screening improvements.), and the sheer number of online platforms that accept OAuth tokenization, ranging from email to social media, e-commerce, entertainment, file hosting, project management tools, etc., it is unrealistic to assume this problem can be contained at the vendor level.

For this reason, businesses need to become more proactive at training employees while also limiting their exposure to phishing-based attacks.

Here are a few steps businesses should take to contain the threat:

  • Incorporate OAuth phishing training into any/all security awareness programs.
  • Update corporate policies to restrict what types of third-party applications may be added to any online service or tool that is linked to the company's information, accounts or network (example: Google, Microsoft, Dropbox, Basecamp, GitHub). However, rather than providing high-level guidance on this, be extremely specific—include a list of pre-approved applications and deny all others not on the list.
  • Implement email whitelisting for executives and key employees.
  • Include OAuth request audits into any current employee email monitoring program.
  • Conduct regular audits of employees' work-related online accounts to check for rogue permission requests and purge any suspicious applications.
  • Require employees to use file encryption tools to protect sensitive corporate information that is sent or stored in email.
  • Establish a strong access control program, so that no single employee has too much access to corporate systems, accounts, data, or key personnel.
  • Segment the network sufficiently to limit the lateral spread of attacks.

OAuth phishing is likely to pose a long-term challenge to businesses, and as such it will require a more robust security program to contain the threats posed by these more-sophisticated phishing emails.

Related Content:

Greg Martin is CEO of JASK (jask.ai), a Silicon Valley-based cybersecurity startup that has developed a unique enterprise security platform to dramatically improve situational awareness of cyberthreats. Martin is a former cybersecurity technical advisor to the FBI and Secret ... View Full Bio
Comment  | 
Print  | 
More Insights
Comments
Newest First  |  Oldest First  |  Threaded View
JulietteRizkallah
50%
50%
JulietteRizkallah,
User Rank: Ninja
5/8/2017 | 3:59:43 PM
Good case for Identity governance
This seems like a good case for Idenity Governance to monitor and control access, certify access through regurlar campaigns, idenity rogue and orphan accounts and revoke compromised accounts when needed.
Valentine's Emails Laced with Gandcrab Ransomware
Kelly Sheridan, Staff Editor, Dark Reading,  2/14/2019
High Stress Levels Impacting CISOs Physically, Mentally
Jai Vijayan, Freelance writer,  2/14/2019
Mozilla, Internet Society and Others Pressure Retailers to Demand Secure IoT Products
Curtis Franklin Jr., Senior Editor at Dark Reading,  2/14/2019
Register for Dark Reading Newsletters
White Papers
Video
Cartoon
Current Issue
5 Emerging Cyber Threats to Watch for in 2019
Online attackers are constantly developing new, innovative ways to break into the enterprise. This Dark Reading Tech Digest gives an in-depth look at five emerging attack trends and exploits your security team should look out for, along with helpful recommendations on how you can prevent your organization from falling victim.
Flash Poll
How Enterprises Are Attacking the Cybersecurity Problem
How Enterprises Are Attacking the Cybersecurity Problem
Data breach fears and the need to comply with regulations such as GDPR are two major drivers increased spending on security products and technologies. But other factors are contributing to the trend as well. Find out more about how enterprises are attacking the cybersecurity problem by reading our report today.
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2019-7629
PUBLISHED: 2019-02-18
Stack-based buffer overflow in the strip_vt102_codes function in TinTin++ 2.01.6 and WinTin++ 2.01.6 allows remote attackers to execute arbitrary code by sending a long message to the client.
CVE-2019-8919
PUBLISHED: 2019-02-18
The seadroid (aka Seafile Android Client) application through 2.2.13 for Android always uses the same Initialization Vector (IV) with Cipher Block Chaining (CBC) Mode to encrypt private data, making it easier to conduct chosen-plaintext attacks or dictionary attacks.
CVE-2019-8917
PUBLISHED: 2019-02-18
SolarWinds Orion NPM before 12.4 suffers from a SYSTEM remote code execution vulnerability in the OrionModuleEngine service. This service establishes a NetTcpBinding endpoint that allows remote, unauthenticated clients to connect and call publicly exposed methods. The InvokeActionMethod method may b...
CVE-2019-8908
PUBLISHED: 2019-02-18
An issue was discovered in WTCMS 1.0. It allows remote attackers to execute arbitrary PHP code by going to the "Setting -> Mailbox configuration -> Registration email template" screen, and uploading an image file, as demonstrated by a .php filename and the "Content-Type: image/g...
CVE-2019-8909
PUBLISHED: 2019-02-18
An issue was discovered in WTCMS 1.0. It allows remote attackers to cause a denial of service (resource consumption) via crafted dimensions for the verification code image.