Dark Reading is part of the Informa Tech Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them.Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.

Application Security

12/4/2019
11:00 AM
Kelly Sheridan
Kelly Sheridan
Quick Hits
Connect Directly
Twitter
LinkedIn
Google+
RSS
E-Mail
50%
50%

Microsoft Issues Advisory for Windows Hello for Business

An issue exists in Windows Hello for Business when public keys persist after a device is removed from Active Directory, if the AD exists, Microsoft reports.

Microsoft has issued an advisory (ADV190026) to provide guidance to businesses following the disclosure of an issue in Windows Hello for Business (WHfB). The problem exists when public keys persist following a device's removal from Active Directory, if the Active Directory exists.

The issue was discovered by Michael Grafnetter, IT security researcher and trainer for CQURE and GOPAS, who has been investigating the inner workings of WHfB and discovered multiple attack vectors for the passwordless authentication tool. One of these vectors involves msDS-KeyCredentialLink, which could potentially be used or misused for persistence by an attacker.

Today's advisory refers to another one of his findings. When someone sets up WHfB, the WHfB public key is written to the on-premises AD, and its keys are tied to a user and device that has been added to Azure AD. If the device is removed, its linked WHfB key is considered orphaned. However, these orphaned keys are not deleted, even if their corresponding device is removed. While any authentication to Azure AD using an orphaned key will be rejected, some of these WHfB keys cause a security issue in AD 2016 and 2019 in hybrid or on-premises environments.

An authenticated attacker could access orphaned keys created on Trusted Platform Modules (TPMs) affected by CVE-2017-15361, as detailed in separate security advisory ADV170012, to compute their WHfB private key using the orphaned public keys. The attacker could use the stolen private key to authenticate as the user within the domain with Public Key Cryptography for Initial Authentication (PKINIT).

"This attack is possible even if firmware and software updates have been applied to TPMs that were affected by CVE-2017-15361 because the corresponding public keys might still exist in Active Directory," Microsoft explains in its advisory. Its advisory is intended to provide guidance to clean up orphaned public keys created using an unpatched TPM, before the updates detailed in ADV170012 were applied.

So far, there is no evidence to suggest this issue has been used to attack machines in the wild, officials say. Read mitigation steps in Microsoft's full advisory here.

Check out The Edge, Dark Reading's new section for features, threat data, and in-depth perspectives. Today's top story: "A Cause You Care About Needs Your Cybersecurity Help."

Kelly Sheridan is the Staff Editor at Dark Reading, where she focuses on cybersecurity news and analysis. She is a business technology journalist who previously reported for InformationWeek, where she covered Microsoft, and Insurance & Technology, where she covered financial ... View Full Bio

Comment  | 
Print  | 
More Insights
Comments
Newest First  |  Oldest First  |  Threaded View
Mobile Banking Malware Up 50% in First Half of 2019
Kelly Sheridan, Staff Editor, Dark Reading,  1/17/2020
Active Directory Needs an Update: Here's Why
Raz Rafaeli, CEO and Co-Founder at Secret Double Octopus,  1/16/2020
New Attack Campaigns Suggest Emotet Threat Is Far From Over
Jai Vijayan, Contributing Writer,  1/16/2020
Register for Dark Reading Newsletters
White Papers
Video
Cartoon Contest
Write a Caption, Win a Starbucks Card! Click Here
Latest Comment: I've never actually seen the corporate ladder before.
Current Issue
The Year in Security: 2019
This Tech Digest provides a wrap up and overview of the year's top cybersecurity news stories. It was a year of new twists on old threats, with fears of another WannaCry-type worm and of a possible botnet army of Wi-Fi routers. But 2019 also underscored the risk of firmware and trusted security tools harboring dangerous holes that cybercriminals and nation-state hackers could readily abuse. Read more.
Flash Poll
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2020-5216
PUBLISHED: 2020-01-23
In Secure Headers (RubyGem secure_headers), a directive injection vulnerability is present in versions before 3.9.0, 5.2.0, and 6.3.0. If user-supplied input was passed into append/override_content_security_policy_directives, a newline could be injected leading to limited header injection. Upon seei...
CVE-2020-5217
PUBLISHED: 2020-01-23
In Secure Headers (RubyGem secure_headers), a directive injection vulnerability is present in versions before 3.8.0, 5.1.0, and 6.2.0. If user-supplied input was passed into append/override_content_security_policy_directives, a semicolon could be injected leading to directive injection. This could b...
CVE-2020-5223
PUBLISHED: 2020-01-23
In PrivateBin versions 1.2.0 before 1.2.2, and 1.3.0 before 1.3.2, a persistent XSS attack is possible. Under certain conditions, a user provided attachment file name can inject HTML leading to a persistent Cross-site scripting (XSS) vulnerability. The vulnerability has been fixed in PrivateBin v1.3...
CVE-2019-20399
PUBLISHED: 2020-01-23
A timing vulnerability in the Scalar::check_overflow function in Parity libsecp256k1-rs before 0.3.1 potentially allows an attacker to leak information via a side-channel attack.
CVE-2020-7915
PUBLISHED: 2020-01-22
An issue was discovered on Eaton 5P 850 devices. The Ubicacion SAI field allows XSS attacks by an administrator.