# CVE-2017-7901: Weak cryptography in Rockwell Automation Allen-Bradley MicroLogix 1100 and 1400 > Attackers can predict TCP sequence numbers to spoof or disrupt connections, causing denial of service on Rockwell Automation PLCs. - **Severity:** High 8.6 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/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:** 30 Jun 2017 - **Updated:** 5 Aug 2024 - **Also known as:** GHSA-9mhw-mx58-2jch ## What is CVE-2017-7901? CVE-2017-7901 is a high-severity vulnerability in Rockwell Automation Allen-Bradley MicroLogix 1100 and 1400, published on 30 Jun 2017. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description A Predictable Value Range from Previous Values issue was discovered in Rockwell Automation Allen-Bradley MicroLogix 1100 programmable-logic controllers 1763-L16AWA, Series A and B, Version 16.00 and prior versions; 1763-L16BBB, Series A and B, Version 16.00 and prior versions; 1763-L16BWA, Series A and B, Version 16.00 and prior versions; and 1763-L16DWD, Series A and B, Version 16.00 and prior versions and Allen-Bradley MicroLogix 1400 programmable logic controllers 1766-L32AWA, Series A and B, Version 16.00 and prior versions; 1766-L32BWA, Series A and B, Version 16.00 and prior versions; 1766-L32BWAA, Series A and B, Version 16.00 and prior versions; 1766-L32BXB, Series A and B, Version 16.00 and prior versions; 1766-L32BXBA, Series A and B, Version 16.00 and prior versions; and 1766-L32AWAA, Series A and B, Version 16.00 and prior versions. Insufficiently random TCP initial sequence numbers are generated, which may allow an attacker to predict the numbers from previous values. This may allow an attacker to spoof or disrupt TCP connections, resulting in a denial of service for the target device. Weakness: CWE-330 (Use of Insufficiently Random Values), CWE-343 (Predictable Value Range from Previous Values) ## Which versions are affected by CVE-2017-7901? It affects 20 products. Products: Rockwellautomation 1763-L16awa Series A, Rockwellautomation 1763-L16awa Series B, Rockwellautomation 1763-L16bbb Series A, Rockwellautomation 1763-L16bbb Series B, Rockwellautomation 1763-L16bwa Series A, Rockwellautomation 1763-L16bwa Series B, Rockwellautomation 1763-L16dwd Series A, Rockwellautomation 1763-L16dwd Series B, Rockwellautomation 1766-L32awa Series A, Rockwellautomation 1766-L32awa Series B, Rockwellautomation 1766-L32awaa Series A, Rockwellautomation 1766-L32awaa Series B, Rockwellautomation 1766-L32bwa Series A, Rockwellautomation 1766-L32bwa Series B, Rockwellautomation 1766-L32bwaa Series A, Rockwellautomation 1766-L32bwaa Series B, Rockwellautomation 1766-L32bxb Series A, Rockwellautomation 1766-L32bxb Series B, Rockwellautomation 1766-L32bxba Series A, Rockwellautomation 1766-L32bxba Series B. ## How do I fix CVE-2017-7901? No fix has been published for CVE-2017-7901 yet. Limit exposure of the affected software until one is available. ## Is CVE-2017-7901 being exploited? There is no known exploitation of CVE-2017-7901 in the wild and no public exploit code. ## Other vulnerabilities in Rockwell Automation Allen-Bradley MicroLogix 1100 and 1400 - [CVE-2017-7898](https://insights.sbomify.com/CVE-2017-7898/): Auth bypass in Rockwell Automation Allen-Bradley MicroLogix 1100 and 1400 (critical 9.8) - [CVE-2017-7899](https://insights.sbomify.com/CVE-2017-7899/): Information disclosure in Rockwell Automation Allen-Bradley MicroLogix 1100 and 1400 (critical 9.8) - [CVE-2017-7902](https://insights.sbomify.com/CVE-2017-7902/): Weak cryptography in Rockwell Automation Allen-Bradley MicroLogix 1100 and 1400 (critical 9.8) - [CVE-2017-7903](https://insights.sbomify.com/CVE-2017-7903/): Weak cryptography in Rockwell Automation Allen-Bradley MicroLogix 1100 and 1400 (critical 9.8) - [CVE-2016-0868](https://insights.sbomify.com/CVE-2016-0868/): Memory corruption in n/a (critical 9.8) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2017-7901 and fix it if it is affected. What it is: CVE-2017-7901 is a high-severity vulnerability in Rockwell Automation Allen-Bradley MicroLogix 1100 and 1400, published on 30 Jun 2017. 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-2017-7901 in the wild and no public exploit code. Affected product: Rockwell Automation Allen-Bradley MicroLogix 1100 and 1400. 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-2017-7901/ (Markdown: https://insights.sbomify.com/CVE-2017-7901/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2017-7901 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2017-7901 - OSV: https://osv.dev/vulnerability/CVE-2017-7901 --- From sbomify Insights: https://insights.sbomify.com/CVE-2017-7901/ Summaries are generated and may contain mistakes; the official description above is the record.