A zero-day exploit refers to any cyberattack that uses an unaddressed attack vector.
For example, Microsoft Windows operating systems are regularly patched to address potentially serious security issues — and as soon as those issues are discovered, Microsoft has “zero days” to implement a fix (hence the name).
But Microsoft isn’t perfect, and no version of Windows is perfect, either. In May of 2024, the company announced a fix for a zero-day bug that allowed attackers to execute code (after tricking the user into downloading certain files).
Zero-day bugs aren’t specific to operating systems. Every type of software can have potential exploits, but the issues are more serious when software has a significant level of permissions. A file transfer app with a serious security flaw could create an enormous vulnerability (and that’s exactly what happened with the 2023 MOVEit hack).
What is zero-day malware?
Zero-day malware simply refers to any type of malicious software (such as ransomware) that takes advantage of an unknown/unprotected vulnerability.
Once again, “zero-day” is simply shorthand for the attack vector — it doesn’t imply anything else about how the malicious software works or its threat level.
Are all zero-day bugs exploited by bad actors?
Not at all. In fact, security researchers are responsible for identifying most zero-day issues. They’ll typically inform the software vendor, which can then address the exploit.
IBM estimates that most exploits are addressed within 14 days of vulnerability disclosure (the date when the software dev team knows about the issue).
How can I avoid zero-day malware?
By far, the most effective step you can take is to set up automatic updates for your operating system and all important software (where available). This mitigates most common attacks.
The MOVEit hack, for example, was actually resolved fairly quickly — but successful attacks continued for months, simply because many businesses failed to update their software.
Other tips:
- Don’t download software from unknown sources. Don’t pirate software or download cracks/key generators.
- Don’t download email attachments from sources you don’t recognize.
- Don’t open executable files downloaded through email, even if you do recognize the source (unless you can verify the contents of the file).
- Use firewalls with up-to-date security rules to prevent unauthorized connections.
- Use strong passwords and multi-factor authentication.
- For organizations: Educate users about the risks of downloading files from unauthorized sources. Establish strong security protocols and perform regular risk assessments.
For additional help, contact the ransomware experts at Datarecovery.com by calling 1-800-237-4200.
With resources for ransomware recovery, penetration (PEN) testing, and dark web monitoring, we help clients respond to the threat of ransomware — and build resilient, self-sustainable strategies.
