Connect with us

Hi, what are you looking for?

SecurityWeekSecurityWeek

New details have emerged showing that the Flame malware abused Microsoft’s Windows Update mechanism to infect computers.

According to new information revealed by researchers, three modules of the Flame malware – named Snack, Gadget and Munch – are used to launch what is essentially a man-in-the-middle attack against other computers on a network.

Flame Malware Compromised Windows Update

“When a machine tries to connect to Microsoft’s Windows Update, it redirects the connection through an infected machine and it sends a fake, malicious Windows Update to the client,” blogged Alexander Gostev, head of the Global Research and Analysis team at Kaspersky Lab. 

“When a victim updates itself via Windows Update, the query is intercepted and the fake update is pushed,” he explained. “The fake update proceeds to download the main body and infect the computer.”

According to Symantec’s Security Response team, the Snack module sniffs NetBIOS requests on the local network. NetBIOS name resolution allows computers to find each other on a local network via peer-to-peer, opening up an avenue for spoofing.

“When clients attempt to resolve a computer name on the network, and in particular make WPAD (Web Proxy Auto-Discovery Protocol) requests, Flamer will claim it is the WPAD server and provide a rogue WPAD configuration file (wpad.dat),” Symantec noted. “NetBIOS WPAD hijacking is a well-known technique and many publicly available hack tools have implemented the technique.”

“Once a computer that has not yet been compromised receives the rogue wpad.dat file, it will set its proxy server to the Flamer-compromised computer,” the firm noted. “All its web traffic will now be redirected to the Flamer compromised computer first.”

Advertisement. Scroll to continue reading.

The Munch component is a Web server within Flamer and receives the redirected traffic and checks for a variety of queries, including matching URLs for Windows Update.

“Hijacking Windows Update is not trivial because updates must be signed by Microsoft,” Symantec’s team added. “However, Flamer bypasses this restriction by using a certificate that chains to the Microsoft Root Authority and improperly allows code signing. So when a Windows Update request is received, the GADGET module through MUNCH provides a binary signed by a certificate that appears to belong to Microsoft.”

The findings have prompted Microsoft to say that it plans to harden Windows Update against attacks in the future, though the company did not immediately reveal details as to how.

“The Flame malware used a cryptographic collision attack in combination with the terminal server licensing service certificates to sign code as if it came from Microsoft,” blogged Mike Reavey, senior director of Microsoft Security Response Center. “However, code-signing without performing a collision is also possible. This is an avenue for compromise that may be used by additional attackers on customers not originally the focus of the Flame malware. In all cases, Windows Update can only be spoofed with an unauthorized certificate combined with a man-in-the-middle attack.”

“To increase protection for customers, the next action of our mitigation strategy is to further harden Windows Update as a defense-in-depth precaution,” he added. “We will begin this update following broad adoption of Security Advisory 2718704 in order not to interfere with that update’s worldwide deployment.”

Related News: Microsoft Certificate Was Used to Sign “Flame” Malware

Tech Insight: What Flame Means to the Enterprise

Written By

Marketing professional with a background in journalism and a focus on IT security.

Click to comment

Trending

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.

Understand how to go beyond effectively communicating new security strategies and recommendations.

Register

Join us for an in depth exploration of the critical nature of software and vendor supply chain security issues with a focus on understanding how attacks against identity infrastructure come with major cascading effects.

Register

Expert Insights

Related Content

Vulnerabilities

Less than a week after announcing that it would suspended service indefinitely due to a conflict with an (at the time) unnamed security researcher...

Cybercrime

The changing nature of what we still generally call ransomware will continue through 2023, driven by three primary conditions.

Cybercrime

A recently disclosed vBulletin vulnerability, which had a zero-day status for roughly two days last week, was exploited in a hacker attack targeting the...

Data Breaches

OpenAI has confirmed a ChatGPT data breach on the same day a security firm reported seeing the use of a component affected by an...

IoT Security

A group of seven security researchers have discovered numerous vulnerabilities in vehicles from 16 car makers, including bugs that allowed them to control car...

Vulnerabilities

A researcher at IOActive discovered that home security systems from SimpliSafe are plagued by a vulnerability that allows tech savvy burglars to remotely disable...

Risk Management

The supply chain threat is directly linked to attack surface management, but the supply chain must be known and understood before it can be...

Cybercrime

Patch Tuesday: Microsoft calls attention to a series of zero-day remote code execution attacks hitting its Office productivity suite.