Here's a case that shows that using a 3rd-party AV out of the box may be safer than Microsoft Defender out of the box: Clickfix.
Original Post
I was looking for a psychologist in my area. I did a search and I opened a result. I got a captcha. It asked me to press ctrl and R, press ctrl and V and then press enter. It was late at night and I wasn't focusing so I did it without thinking☹️ Nothing happened after I pressed enter and then...
www.elevenforum.com
TLD;R
The user pasted a CAPTCHA text into the run dialog box and executed it. Apparently, ESET Home stopped the download, possibly on a URL blacklist.
My Notes:
- Windows Defender didn't block the download.
- Really scanning the .dll file with Windows Defender, ESET Online scanner, and Emsisoft EEK all showed clean.
- Copying the PowerShell string (from the ElevenForum's OP, possibly "out-of-context"), with supposedly MalwareBytes Browser Guard "copying" protection, didn't flag the copying as suspicious.
Maybe Andy Ful's hard_configurator's Powershell Script block would have stopped it.
- MalwareBytes Browser Guard blocked the URL, but the URL is used in PowerShell, not the browser's context.
- MalwareBytes (VT Scan) flags the DLL.
- ESET Home apparently blocked the URL executed in PowerShell context
VT Results
VT scan on
the dll file:
View attachment 298592
VT scan on
the URL:
View attachment 298593
Notes on the AVs above
Congrats to ESET and MalwareBytes above. This is one of the few times I see MalwareBytes (on VT) flagging this faster than almost everybody else.
A Windows Defender user, with an ad blocker and some security extension (including MalwareBytes Browser Guard and Bitdefender Trafficlight) may not have stopped this.
We don't know the original URL that the OP clicked on that showed the CAPTCHA's powershell script, however.
ClickFix is a good example of how “user-executed script” attacks can slip past default protections, and it also shows why URL/reputation blocking can matter as much as (or more than) file scanning.
That said, this single incident isn’t strong evidence that Microsoft Defender is inherently weaker “out of the box” than any specific third-party AV—what you’re really seeing is a combination of (1) execution context, (2) default feature settings, and (3) which vendor had reputation coverage for that specific URL/infrastructure at that moment.
What ClickFix changes about the usual “download-and-scan” model
ClickFix-style lures typically rely on social engineering to get the victim to run a command (Run dialog / PowerShell) that then pulls a payload or loader.
Key implication: if the initial stage is a script/one-liner and the payload is fetched dynamically, there may be no obvious “browser download event” for browser-focused protections to intercept, and static scanning of a single dropped DLL may not reflect what actually executed (or what would have executed next).
Why ESET might have stopped it while Defender didn’t (without assuming anything about “quality”)
There are a few common, non-controversial reasons a third-party product can appear to “win” in cases like this:
- Web/URL reputation in more places: many suites hook network traffic broadly, so a URL used by PowerShell can still be checked against their reputation/blacklists.
- Different cloud telemetry and takedown speed: one vendor may have classified that specific domain/path earlier, even if the final file wasn’t widely detected yet.
- Default configuration differences: some products ship with more aggressive web filtering enabled by default than Windows does.
On the Defender side, several relevant layers are either not guaranteed to be “on” or equally effective in every context by default (depending on Windows edition, policy, and configuration), such as stronger network protection modes, more aggressive ASR rules, or application control.
Why “the DLL scans clean locally” but VT shows a few detections
This pattern is common in fast-moving campaigns and doesn’t automatically validate either side:
- Local scanners may not flag a new/low-prevalence file yet, especially if it’s a loader, signed, packed, or otherwise not matching strong signatures.
- VirusTotal results are useful for triage, but a small number of detections (or a single vendor) is not definitive proof on its own, and “clean” is also not proof of safety.
- In staged attacks, the first payload can be intentionally low-detection and only fetch the real malware later.
So the “real” protection event in your example may have been URL/network reputation (ESET) rather than classic on-disk detection of the DLL.
Why Browser Guard / TrafficLight may not help much here
If the user never actually downloads via the browser in a normal way (and instead PowerShell retrieves content), a browser extension may have limited visibility. Some extensions also focus on in-browser navigation and known malicious pages, not arbitrary PowerShell web requests.
Practical takeaway for Defender users (without switching products)
Defender can be significantly stronger than its defaults when hardened. The general, low-risk steps that tend to help against this class of attack are:
- Keep cloud-delivered protection and automatic sample submission enabled.
- Keep SmartScreen enabled (and don’t bypass warnings).
- Consider enabling stronger attack surface reduction / script abuse mitigations (what you mentioned about Hard_Configurator’s PowerShell restrictions is in the right direction conceptually).
- Most importantly: treat any site asking you to paste a “CAPTCHA command” into Run/PowerShell as a red flag and exit immediately.
If someone already ran the command
The safest guidance is to treat it as a potential compromise even if scans are clean:
- Disconnect from the network if possible.
- Run scans with at least one reputable second-opinion scanner and review persistence points (scheduled tasks, startup entries, services).
- Change passwords from a known-clean device if there’s any chance credentials were exposed.
- If there are strong indications of compromise and no trustworthy way to validate cleanup, a clean reinstall is the most reliable endpoint.
Overall, your example supports a narrower conclusion: “URL/reputation controls that apply to PowerShell/web requests can stop ClickFix earlier than file-based scanning,” which may or may not be true “out of the box” depending on the product and Windows configuration.
