External risk intelligence

Allen-Bradley Controllers: Excessive Authentication Attempts Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2017-7898

Rockwell Automation Allen-Bradley MicroLogix controllers are affected by a vulnerability allowing unlimited incorrect password attempts. This could permit unauthorized access to operational systems and data, posing a business risk.

2Halo Surface Signal

Rockwellautomation 1763 L16awa Series A

16.000 and earlier

External exposure likelihood

Halo Surface Signal score for CVE-2017-7898

The affected devices are Programmable Logic Controllers (PLCs) used in industrial control environments. While they are network-reachable, they are typically deployed within segmented, internal operational technology (OT) networks behind firewalls or gateways, not directly exposed to the public internet in standard deployments.

PCI scan relevance

PCI Relevance for CVE-2017-7898

Yes

CVE-2017-7898 — Halo PCI Relevance: Yes. Under typical PCI ASV external scan criteria, this issue may be flagged for scan prioritization.

This vulnerability allows repeated incorrect password entries, potentially causing a PCI ASV scan failure due to weak credential protections.

Scan-prioritization guidance only—not a PCI DSS certification or ASV attestation.

Horizon Alert

Summary of the vulnerability and why it matters

The Rockwell Automation Allen-Bradley MicroLogix controllers are susceptible to an issue where there are no restrictions on repeated incorrect password entries. This weakness allows for excessive authentication attempts without consequence. The primary business impact stems from potential unauthorized access to systems and data.

Vulnerable controllers and devices
Excessive failed login attempts allowed
Potential unauthorized system access

Attack Path

How an attacker could exploit the issue

This vulnerability allows an attacker to repeatedly attempt password entry without any lockout. This could enable brute-force attacks against the controller's authentication mechanism. An attacker who gains unauthorized access to the controller could then potentially manipulate industrial processes or access sensitive operational data.

Network exposure required.
Attacker attempts password entry.
Control or data access gained.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability impacts Rockwell Automation Allen-Bradley MicroLogix programmable logic controllers. An attacker could repeatedly attempt incorrect passwords without penalty, potentially leading to unauthorized access. The potential for broad impact and the lack of inherent protective measures suggest a significant risk to operational systems.

Likely attacker skill level: Low
Required access or conditions: Network access
Business risk or urgency: High

Priority actions

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability in Rockwell Automation controllers could allow an attacker to bypass authentication mechanisms. This could potentially lead to unauthorized access and control over industrial systems, posing a risk to operational integrity and safety. Organizations using the affected devices should take immediate steps to identify and secure their systems.

Identify all affected Rockwell Automation controllers.
Isolate vulnerable controllers from external access.
Apply vendor updates and validate fix.
Monitor for unusual activity.

Frequently asked questions

What specific Rockwell Automation controllers are affected by the excessive authentication attempts vulnerability?

The vulnerability impacts Rockwell Automation Allen-Bradley MicroLogix 1100 and MicroLogix 1400 programmable logic controllers. This includes various series and versions of models such as 1763-L16AWA, 1763-L16BBB, 1763-L16BWA, 1763-L16DWD, 1766-L32AWA, 1766-L32BWA, 1766-L32BWAA, 1766-L32BXB, and 1766-L32BXBA, all up to version 16.00.

What type of weakness does CVE-2017-7898 represent, and how does it function?

CVE-2017-7898 is classified as an Improper Restriction of Excessive Authentication Attempts (CWE-307). The weakness lies in the fact that the affected controllers do not enforce any limitations on the number of incorrect password attempts. This allows an attacker to repeatedly try different passwords without any lockout mechanism preventing their progress.

How might an attacker exploit this vulnerability, and what is the scope of impact?

An attacker could leverage this weakness by repeatedly attempting to guess passwords, effectively performing a brute-force attack. If successful, they could gain unauthorized access to the controller. The scope of impact is significant, as unauthorized access to these industrial controllers could lead to the manipulation of critical industrial processes or the theft of sensitive operational data.

What is the overall threat advisory for this vulnerability, considering its network exposure and potential impact?

The threat advisory indicates that while the affected Programmable Logic Controllers (PLCs) are network-reachable, they are typically found within segmented industrial networks, making direct public internet exposure less common. However, the vulnerability itself, an Improper Restriction of Excessive Authentication Attempts, presents a critical risk due to the potential for unauthorized access and control over industrial operations if an attacker gains network access. The Halo Surface Signal classifies this as...

What practical steps should organizations take to address this vulnerability in their Rockwell Automation controllers?

Organizations using affected Rockwell Automation controllers should prioritize identifying all instances of the vulnerable devices within their network. It is crucial to isolate these controllers from external network access and apply any available vendor updates or patches to remediate the weakness. Continuous monitoring for unusual activity on these controllers is also recommended to detect any potential exploitation attempts.

References

Written by Nicholas Merritt

External-surface CVE analysis and Halo Surface Signal prioritization for Halo Threat Intelligence.