We are alerting Windows users of a new type of ransomware that exhibits worm-like behavior. This ransom leverages removable and network drives to propagate itself and affect more users. We detect this ransomware as Ransom:Win32/ZCryptor.A. Infection vector Ransom:Win32/ZCryptor.A is distributed through the spam email infection vector. It also gets installed in your machine through…
Limited Periodic Scanning in Windows 10 to Provide Additional Malware Protection
Every month, Microsoft’s Malicious Software Removal Tool (MSRT) scans more than 500 million Windows devices for malware and malicious software. This tool aids in the detection and removal of malware from 1 to 2 million machines each time, even on those devices running antivirus software. Meanwhile, many Windows customers continue to use the Microsoft Safety…
The 5Ws and 1H of Ransomware
For the past three months, we have seen ransomware hop its way across globe. Majority of the ransomware incidents are found in the United States, then Italy, and Canada. The prevalence of large-scale ransomware incidents led the United States and Canadian governments to issue a joint statement about ransomware. Due to the global ransomware incidents, the…
Malicious macro using a sneaky new trick
We recently came across a file (ORDER-549-6303896-2172940.docm, SHA1: 952d788f0759835553708dbe323fd08b5a33ec66) containing a VBA project that scripts a malicious macro (SHA1: 73c4c3869304a10ec598a50791b7de1e7da58f36). We added it under the detection TrojanDownloader:O97M/Donoff – a large family of Office-targeting macro-based malware that has been active for several years (see our blog category on macro-based malware for more blogs). However, there wasn’t…
Large Kovter digitally-signed malvertising campaign and MSRT cleanup release
Kovter is a malware family that is well known for being tricky to detect and remove because of its file-less design after infection. Users from United States are nearly exclusively being targeted, and infected PCs are used to perform click-fraud and install additional malware on your machine. Starting April 21, 2016, we observed a large…
Gamarue, Nemucod, and JavaScript
JavaScript is now being used largely to download malware because it’s easy to obfuscate the code and it has a small size. Most recently, one of the most predominant JavaScript malware that has been spreading other malware is Nemucod. This JavaScript trojan downloads additional malware (such as Win32/Tescrypt and Win32/Crowti – two pervasive ransomware trojans…
Digging deep for PLATINUM
This blog introduces our latest report from the Windows Defender Advanced Threat Hunting team. You can read the full report at: PLATINUM: Targeted attacks in South and Southeast Asia There is no shortage of headlines about cybercriminals launching large-scale attacks against organizations. For us, the activity groups that pose the most danger are the ones…
A brief discourse on ‘Changing browsing experience’
In response to questions we’ve received from the software distribution and monetization industry, and following our blog announcing our browser modifier policy update, we’d like to provide some details on what we refer to in our policy as “changing browsing experience”. For us, “changing browsing experience” means behaviors that modify the content of webpages. We…
JavaScript-toting spam emails: What should you know and how to avoid them?
We have recently observed that spam campaigns are now using JavaScript attachments aside from Office files. The purpose of the code is straightforward. It downloads and runs other malware. Some of the JavaScript downloaders that we’ve seen are: TrojanDownloader:JS/Swabfex TrojanDownloader:JS/Nemucod TrojanDownloader:JS/Locky The same JavaScript downloaders are also responsible for spreading the following ransomware: Ransom:Win32/Tescrypt Ransom:Win32/Locky…
MSRT April release features Bedep detection
As part of our ongoing effort to provide better malware protection, the Microsoft Malicious Software Removal Tool (MSRT) release this April will include detections for: Win32/Bedep – Trojan family Win32/Upatre – Trojan family Ransom:MSIL/Samas – Ransomware family In this blog, we’ll focus on the Bedep family of trojans. The bothersome Bedep Win32/Bedep was first…