CVE-2021-25663 : Security Advisory and Response

A vulnerability has been identified in multiple Siemens products allowing attackers to create an infinite loop with crafted length values. Learn more about the impact, technical details, and mitigation strategies.

Understanding CVE-2021-25663

This CVE pertains to a vulnerability found in various Siemens products that can be exploited to cause an infinite loop with manipulated length values, potentially leading to denial-of-service conditions.

What is CVE-2021-25663?

The vulnerability in Siemens products such as Capital VSTAR and Nucleus NET arises from a failure to validate extension header lengths in the processing of IPv6 headers. This oversight enables attackers to trigger an infinite loop, disrupting the normal operation of affected systems.

The Impact of CVE-2021-25663

Exploitation of this vulnerability can result in denial-of-service conditions on the affected systems. By sending specially crafted packets, threat actors can force the target system into an infinite loop, rendering it unresponsive and impacting its availability.

Technical Details of CVE-2021-25663

The technical description of this CVE provides insight into the specific components and versions affected along with the mechanism of exploitation.

Vulnerability Description

The flaw lies in the processing of IPv6 headers within Siemens products, where inadequate validation of extension header lengths allows threat actors to orchestrate an infinite loop scenario by manipulating these values.

Affected Systems and Versions

Siemens products including Capital VSTAR, Nucleus NET, Nucleus ReadyStart V3, Nucleus ReadyStart V4, and Nucleus Source Code are susceptible to this vulnerability. Versions prior to specific release numbers are impacted.

Exploitation Mechanism

Threat actors can exploit this vulnerability by sending specially crafted packets with manipulated length values of extension header options. By forcing the affected function into an infinite loop, attackers can disrupt the normal operation of the targeted system.

Mitigation and Prevention

Understanding the steps to mitigate and prevent CVE-2021-25663 is crucial in safeguarding vulnerable systems from potential exploitation.

Immediate Steps to Take

Organizations using the affected Siemens products should consider implementing network-level protections, such as intrusion detection systems, to identify anomalous traffic indicative of exploitation attempts. Additionally, applying vendor-supplied patches and updates is essential to remediate the vulnerability.

Long-Term Security Practices

In the long term, organizations should prioritize regular security assessments, including vulnerability scanning and penetration testing, to detect and address potential weaknesses proactively. Employee training on recognizing and responding to suspicious network activity is also vital for enhancing overall cybersecurity posture.

Patching and Updates

Siemens has released patches addressing the vulnerability in Capital VSTAR, Nucleus NET, Nucleus ReadyStart V3, Nucleus ReadyStart V4, and Nucleus Source Code. Organizations are advised to promptly apply these patches to eliminate the identified security risk from their systems.