CVE-2021-31728
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedIncorrect access control in zam64.sys, zam32.sys in MalwareFox AntiMalware 2.74.0.150 allows a non-privileged process to open a handle to \.\ZemanaAntiMalware, register itself with the driver by sending IOCTL 0x80002010, allocate executable memory using a flaw in IOCTL 0x80002040, install a hook with IOCTL 0x80002044 and execute the executable memory using this hook with IOCTL 0x80002014 or 0x80002018, this exposes ring 0 code execution in the context of the driver allowing the non-privileged process to elevate privileges.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceLocal privilege escalation vulnerability in MalwareFox AntiMalware driver (zam64.sys/zam32.sys). The driver fails to validate caller privileges before processing IOCTL requests, allowing a low-privileged user to register with the driver, allocate executable memory, install hooks, and achieve arbitrary code execution in kernel mode (ring 0).
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data= 2.74.0.150CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check if MalwareFox AntiMalware is installedCheck the Windows registry under HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\ for an entry named 'MalwareFox AntiMalware' or look for the installation folder in Program Files or Program Files (x86)Affected if The software is present on the system
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Verify the installed version numberOpen Programs and Features in Control Panel or use 'Get-ItemProperty' on the registry uninstall key to retrieve the DisplayVersion valueAffected if The version displayed is 2.74.0.150
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Locate the vulnerable driver filesSearch for zam64.sys or zam32.sys on the system - typically found in C:\Windows\System32\drivers\ or the MalwareFox installation directoryAffected if Either zam64.sys or zam32.sys file exists on the system
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Check if the driver is currently loadedOpen an elevated command prompt and run 'sc query zam64' or 'sc query zam32' to query the driver service statusAffected if The driver service state shows as RUNNING
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataApply vendor patch when available; until then, consider removing or disabling MalwareFox AntiMalware to eliminate the attack surface, or restrict user access to systems hosting this software.
- Consultation4.0 h
- Implementation24.0 h
- Testing12.0 h
- Review / QA8.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $13,376.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-31728 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-31728 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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