# CVE-2018-4852: Auth bypass in SICLOCK TC100, SICLOCK TC400

> An attacker with network access can bypass authentication on Siemens SICLOCK devices if they possess specific device knowledge.

- **Severity:** Critical 9.8 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 3 Jul 2018
- **Updated:** 17 Sep 2024
- **Also known as:** GHSA-25mm-w8qr-qm89

## What is CVE-2018-4852?

CVE-2018-4852 is a critical authentication bypass vulnerability in Siemens AG SICLOCK TC100, SICLOCK TC400, published on 3 Jul 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability has been identified in SICLOCK TC100 (All versions) and SICLOCK TC400 (All versions). An attacker with network access to the device could potentially circumvent the authentication mechanism if he/she is able to obtain certain knowledge specific to the attacked device.

Weakness: CWE-287 (Improper Authentication), CWE-288 (Authentication Bypass Using an Alternate Path or Channel)

## Which versions are affected by CVE-2018-4852?

It affects 2 products.


Products: Siemens Siclock Tc100 Firmware, Siemens Siclock Tc400 Firmware.

## How do I fix CVE-2018-4852?

No fix has been published for CVE-2018-4852 yet. Limit exposure of the affected software until one is available.

## Is CVE-2018-4852 being exploited?

There is no known exploitation of CVE-2018-4852 in the wild and no public exploit code.

## Other vulnerabilities in Siemens AG SICLOCK TC100, SICLOCK TC400

- [CVE-2018-4853](https://insights.sbomify.com/CVE-2018-4853/): Missing authorization in SICLOCK TC100, SICLOCK TC400 (critical 9.8)
- [CVE-2018-4854](https://insights.sbomify.com/CVE-2018-4854/): Missing authorization in SICLOCK TC100, SICLOCK TC400 (high 8.8)
- [CVE-2018-4851](https://insights.sbomify.com/CVE-2018-4851/): Denial of service in SICLOCK TC100, SICLOCK TC400 (high 8.2)
- [CVE-2018-4855](https://insights.sbomify.com/CVE-2018-4855/): Information disclosure in SICLOCK TC100, SICLOCK TC400 (medium 6.5)
- [CVE-2018-4856](https://insights.sbomify.com/CVE-2018-4856/): Auth bypass in SICLOCK TC100, SICLOCK TC400 (medium 4.9)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-4852 and fix it if it is affected.

What it is: CVE-2018-4852 is a critical authentication bypass vulnerability in Siemens AG SICLOCK TC100, SICLOCK TC400, published on 3 Jul 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2018-4852 in the wild and no public exploit code.

Affected product: Siemens AG SICLOCK TC100, SICLOCK TC400. 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-2018-4852/ (Markdown: https://insights.sbomify.com/CVE-2018-4852/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-4852
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-4852
- OSV: https://osv.dev/vulnerability/CVE-2018-4852

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From sbomify Insights: https://insights.sbomify.com/CVE-2018-4852/
Summaries are generated and may contain mistakes; the official description above is the record.