# CVE-2021-31728: Privilege escalation in n/a

> A local attacker can exploit incorrect access control in MalwareFox drivers to achieve ring 0 code execution and elevate privileges.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 17 May 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-hgc8-6w6r-m2w8

## What is CVE-2021-31728?

CVE-2021-31728 is a high-severity vulnerability in n/a, published on 17 May 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Incorrect 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.

## Which versions are affected by CVE-2021-31728?

It affects 1 product.


Products: Malwarefox Antimalware.

## How do I fix CVE-2021-31728?

No fix has been published for CVE-2021-31728 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-31728 being exploited?

There is no known exploitation of CVE-2021-31728 in the wild and no public exploit code.

Public exploit code:

- vulnerability in zam64.sys, zam32.sys allowing ring 0 code execution. CVE-2021-31727 and CVE-2021-31728 public reference. (github_poc): https://github.com/irql/CVE-2021-31728

## Other vulnerabilities in n/a

- [CVE-2021-31727](https://insights.sbomify.com/CVE-2021-31727/): Missing authorization in n/a (high 7.8)
- [CVE-2018-6606](https://insights.sbomify.com/CVE-2018-6606/): Privilege escalation in n/a (high 7.8)
- [CVE-2018-6593](https://insights.sbomify.com/CVE-2018-6593/): Privilege escalation in n/a (high 7.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-31728 and fix it if it is affected.

What it is: CVE-2021-31728 is a high-severity vulnerability in n/a, published on 17 May 2021. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-31728 in the wild and no public exploit code.

Affected product: n/a. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2021-31728/ (Markdown: https://insights.sbomify.com/CVE-2021-31728/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-31728
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-31728
- OSV: https://osv.dev/vulnerability/CVE-2021-31728

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-31728/
Summaries are generated and may contain mistakes; the official description above is the record.