Security Experts:

Connect with us

Hi, what are you looking for?

SecurityWeekSecurityWeek

Application Security

Windows URI Handling Flaw Leads to Drive-by Code Execution

A pair of German security researchers have publicly documented the discovery of a drive-by code execution vulnerability in Windows 10 and criticized Microsoft for botching its response to the still-unfixed security problem.

A pair of German security researchers have publicly documented the discovery of a drive-by code execution vulnerability in Windows 10 and criticized Microsoft for botching its response to the still-unfixed security problem.

The security defect is an argument injection in the Windows 10/11 default handler for ‘ms-officecmd:’ URIs and was successfully chained with mitigation bypasses to launch single-click browser-based exploits on Microsoft’s flagship operating system.

The research team — Fabian Braunlein and Kukas Euler of Positive Security — published a demo exploit showing a remote code execution drive-by exploit and upbraided Microsoft’s security response center for initially misdiagnosing the severity of the flaw and denying full bug-bounty disclosure payments.

According to a technical paper published this week, Microsoft silently patched the issue after five months of receiving the vulnerability data (the company has not issued a CVE identifier) but Redmond’s patch “ failed to properly address the underlying argument injection.”

[ READ: For Microsoft, Security is a $10 Billion Business ]

The researchers claim the underlying argument injection weakness is currently still present on Windows 11, the newest version of the operating system.

From the research paper:

“Code execution is triggered by a malicious website which performs a Javascript redirect to a crafted ms-officecmd: URI (a scheme used by the Microsoft Office UWP app to launch other Office desktop applications). We exploit an argument injection vulnerability in the URI handler and bypass a security measure in Electron to inject an arbitrary OS command via the –gpu-launcher parameter of the Microsoft Teams Electron app.”

In addition to exploitation via booby-trapped websites, the researchers warn that hackers could launch these code execution attacks via desktop applications that perform unsafe URL handling.

[ SEE: Windows Admins Scrambling to Contain ‘PrintNightmare’ Flaw ]

The research pair published the original advisory it sent to Microsoft and expressed frustration with the company’s responsiveness and communications transparency.

After initially dismissing the vulnerability report, the researchers say Microsoft acknowledged the severity with a “Critical, RCE” classification but paid out only a fraction of the bug bounty advertised for high-severity bugs.

The researchers had to file an appeal just to get the vulnerability acknowledged and then found itself haggling with the software giant over a $5,000 bug bounty payout.  

“We decided to find a code execution vulnerability in a default Windows 10 URI handler, and succeeded within two weeks. Considering the amount of URI handlers Windows ships with, it seems very likely that others are vulnerable too,” the researchers warned.

Related: Did Microsoft Botch the PrintNightmare Patch?

Related: Microsoft Office Zero-Day Hit in Targeted Attacks

Related: NSA Reports New Critical Microsoft Exchange Flaws 

Written By

Ryan Naraine is Editor-at-Large at SecurityWeek and host of the popular Security Conversations podcast series. He is a security community engagement expert who has built programs at major global brands, including Intel Corp., Bishop Fox and GReAT. Ryan is a founding-director of the Security Tinkerers non-profit, an advisor to early-stage entrepreneurs, and a regular speaker at security conferences around the world.

Click to comment

Daily Briefing Newsletter

Subscribe to the SecurityWeek Email Briefing to stay informed on the latest threats, trends, and technology, along with insightful columns from industry experts.

Expert Insights

Related Content

Application Security

Cycode, a startup that provides solutions for protecting software source code, emerged from stealth mode on Tuesday with $4.6 million in seed funding.

Cyberwarfare

Websites of German airports, administration bodies and banks were hit by DDoS attacks attributed to Russian hacker group Killnet

Data Breaches

GoTo said an unidentified threat actor stole encrypted backups and an encryption key for a portion of that data during a 2022 breach.

Network Security

NSA publishes guidance to help system administrators identify and mitigate cyber risks associated with transitioning to IPv6.

Malware & Threats

Microsoft plans to improve the protection of Office users by blocking XLL add-ins from the internet.

Nation-State

The North Korean APT tracked as TA444 is either moonlighting from its previous primary purpose, expanding its attack repertoire, or is being impersonated by...

Identity & Access

Hackers rarely hack in anymore. They log in using stolen, weak, default, or otherwise compromised credentials. That’s why it’s so critical to break the...

Cloud Security

VMware vRealize Log Insight vulnerability allows an unauthenticated attacker to take full control of a target system.