My thoughts on Emsisoft, Bitdefender and other AVs, especially for advanced threat protection
Antivirus Analysis
I'm a reverse engineer and malware analyst, and I've been doing extensive testing on consumer AVs with a focus on how they handle modern evasion techniques (specifically direct syscall-based attacks). I wanted to get the community's thoughts on Emsisoft.
My Testing Background: I created my own PoCs in C++ using various direct syscall techniques to test multiple AVs including VIPRE, ESET, Kaspersky, Windows Defender, G-Data, Trend Micro, Bitdefender and Emsisoft.
My test samples successfully bypassed most industry-leading AVs, but Emsisoft and Bitdefender were the only two that consistently blocked execution at the earliest points in the kill chain.
Why I'm skeptical of AVs like Kaspersky and ESET
Kaspersky's Reactive Approach:
Kaspersky's design philosophy is fundamentally reactive. It lets malware execute while monitoring behavior, then relies on System Watcher and rollback features to clean up damage. This works fine for ransomware or file modifications, but it's completely useless against modern data exfiltration threats such as:
- Discord/client-side token stealers: Data is sent to a remote server the instant it's stolen. You can't "rollback" network transmissions.
- Credential dumping: LSASS credentials exfiltrated in milliseconds
- Browser session cookies/tokens: Stolen and sent to attacker's server in <100ms. Your accounts are compromised before Kaspersky even flags it as suspicious.
By the time Kaspersky's behavioral engine decides "this is malicious" and triggers a rollback, your sensitive data is already on an attacker's server. System Watcher can't undo that.
Emsisoft/Bitdefender block at the syscall level before execution, preventing the theft from ever happening. That's the difference between prevention and damage control.
ESET's Detection Gap:
I'd personally recommend against ESET for advanced threats and zero-days. During my own testing, I found it completely fails to detect direct syscall invocation. I was able to pop calc.exe via shellcode using direct syscalls and ESET didn't even flinch. This may be different in their business suite but I'm specifically talking about the consumer edition (Premium version with LiveGuard enabled).
If it lets me spawn calc.exe undetected via shellcode, that same technique would work for deploying ransomware, credential/token stealers, or any malicious payload. It's a fundamental detection gap that real threats actively exploit.
Emsisoft's Syscall Detection
Bitdefender did detect the threats, but there was a noticeable execution window where malicious code could run before termination due to Bitdefenders reliance on a technique known as "Instrumentation callbacks". Emsisoft however blocked execution at the earliest point in the kill chain, thus preventing the payload from ever running.
The key difference seems to be Emsisoft's behavioral analysis engine catching the syscall patterns before any damage occurs, while Bitdefender relied more on post-execution detection. For zero-day/advanced threats using syscall-based evasion, that timing is make or break.
They have a blog post explaining their new syscall detection system which is nice: New in 2025.5: Syscall Detection
Addressing Outdated Test Results
I know people reference these MalwareTips tests:
Both are now outdated. The January test was before Emsisoft's syscall detection system (added June 10th, 2025). The August test was after the syscall system but before the October 6th maintenance updates that further improved their security engine.
- App Review - Emsisoft Anti-Malware Home 2025 (August 6th 2025)
- App Review - Shadowra's Big Comparative : Episode 2 - Paid Antivirus (January 1st 2025)
The "MBR corruption" in the August test turned out to be a false alarm. It was an open-source C# joke program that isn't even a PUP, much less actual malware.
My recent testing (post-October 6th updates) shows Emsisoft blocks everything I've thrown at it. All my POCs that bypass every other AV except Bitdefender.
My Questions for the Community:
Based on my testing, I would personally recommend Emsisoft or Bitdefender for anyone concerned about advanced threats and want the best protection possible. The choice is up to you, but from a pure protection standpoint against modern evasion techniques, they're the only two I'd trust.
- Has anyone else tested Emsisoft recently (post-October 6th 2025 updates)?
- What are your experiences with Emsisoft's detection rates vs. the "big names" like Kaspersky/ESET/Bitdefender?
- Are there any downsides to Emsisoft I should be aware of?
- For those using it. How's the performance impact and false positive rate?
@Shadowra