Microsoft Defender causes 'mass confusion' after legitimate apps trigger ransomware alerts
The broken update pushed to users on Sunday morning saw the likes of Teams, Slack, Chrome, and Edge all being confused with the dangerous Hive ransomware payloads
Microsoft has fixed a wide-reaching Defender bug that mistakenly flagged popular software as malicious Hive ransomware payloads.
Windows users and system administrators were reporting common problems over the weekend following an update to Defender that was causing the anti-malware solution to flag Electron-based and Chromium-based software to generate a false positive detection.
Business software such as Slack, Chrome, and Edge were affected, as were consumer-facing apps like Discord and Spotify, users reported. The Defender alert was triggered every time an affected application was opened.
The alert pushed to users states that Defender blocked a threat and the affected application has been removed, though it was soon realised the deletion stage failed and the legitimate app that triggered the alert wasn’t removed.
The Microsoft security intelligence update for Defender that catalysed the myriad false positives was pushed to users on Sunday morning.
It was one of four released throughout the day and was ultimately fixed with version 1.373.1537.0, according to user reports across various online communities, which was released around 12 hours later.
Windows users are advised to upgrade to this version or newer. There have since been three additional versions added to the changelog today, with the most recent being 1.373.1567.0 at the time of writing.
RELATED RESOURCE
Cyber resiliency and end-user performance
Reduce risk and deliver greater business success with cyber-resilience capabilities
“We have released an update to address this issue and customers using automatic updates for Microsoft Defender do not need to take additional action,” Microsoft told Bleeping Computer.
The IT community has been largely left to investigate the issue itself as Microsoft’s public-facing channels have not addressed the incident.
This could be due to the country’s workforce being away from the office as it celebrates Labor Day today.
Updates triggering false positives in Defender are fairly rare, although there are recent examples of how it can create panic among IT admins.
Back in March 2022, Microsoft Defender caused confusion en masse as it dropped false positive ransomware alerts to users in large volumes.
Blamed on a “code issue” at the time, Microsoft fixed the issue expeditiously that saw legitimate Office files being mistakenly flagged as ransomware while other behaviours such as backup processes deleting shadow copies also triggered the false alerts.
-
Working with the enemy: Ransomware negotiator-turned cyber criminal jailed after working with hackers to extort clientsNews Angelo Martino was supposed to be negotiating on behalf of victims, but was secretly working for ransomware operators
-
Hackers are posing as Interpol to target small businesses – here's what you need to knowNews Small businesses are warned to think twice before clicking on links
-
‘Every hour ransomware goes undetected drastically increases its potential blast radius’: Hackers are breaching networks and laying low for longer – and nearly half of firms don’t realize until data is stolenNews An ExtraHop survey found more intrusions are going undetected, leading to longer dwell times
-
Ransomware cartels are fragmenting into volatile splinter groups, warns Met Police cyber chiefNews Commoditized "cyber crime bazaars" and AI data mining are forcing law enforcement to rewrite its playbook
-
New ransomware threat group, The Gentlemen, has become one of the most active ransomware operators, accounting for 10% of all attacksNews NTT researchers warn that the RaaS group is leveraging SystemBC malware to establish covert tunnelling, evade detection, and support rapid lateral movement across enterprise environments
-
Instructure chose to a pay ransom following the Canvas cyber attack – research shows more than half of security leaders would follow suitAnalysis Opting to pay ransoms creates huge risks for enterprises – you’re relying on the word of criminals
-
Ransomware negotiator sentenced for role in major cyber crime groupNews Deniss Zolotarjovs was a key player in a group associated with Conti
-
Threat actors ditch ‘spray and pray’ attacks in shift to targeted exploitationNews A dip in ransomware volumes points to a more targeted approach focused on vulnerability exploitation
