CVE-2021-28667 is a high-severity vulnerability affecting StackStorm versions prior to 3.4.1. This vulnerability allows an infinite loop to occur under certain conditions, specifically when Python 3.x is utilized, the locale is not set to UTF-8, and there is an attempt to log Unicode data from an action or rule name. The vulnerability has a CVSS score of 7.5, indicating significant risk, particularly due to its potential to cause resource exhaustion, impacting availability.
The risk to organizations includes severe degradation of service or complete outages, particularly in environments where resource management is critical. As the vulnerability can be triggered without the need for authentication or user interaction, it presents a notable threat vector that must be addressed promptly. Organizations should prioritize patching to version 3.4.1 or later to eliminate this risk.
Currently, there are no known exploits in the wild specifically targeting this vulnerability, but the potential for exploitation exists given the conditions required to trigger it. Organizations are advised to monitor for any updates from StackStorm and implement the necessary patches without delay.
Urgency for defenders is high. Organizations should prioritize patching immediately to safeguard their systems against this vulnerability and ensure operational continuity.
Vulnerability Details
The official description of CVE-2021-28667 states that StackStorm before 3.4.1 has an infinite loop that consumes all available memory and disk space. This can occur if Python 3.x is used, the locale is not utf-8, and there is an attempt to log Unicode data from an action or rule name.
The CVSS score of 7.5 classifies this vulnerability as high severity. The primary attack vector is through the network, with a low attack complexity and no privileges required. This means that an attacker can exploit this vulnerability without needing prior access to the system.
The affected product is StackStorm, specifically versions prior to 3.4.1, and the CWE classification for this vulnerability is CWE-835.
Technical Analysis
The root cause of CVE-2021-28667 lies in the handling of Unicode data in StackStorm when certain locale settings are used. When an action or rule name that contains Unicode characters is logged, it can trigger an infinite loop, which leads to resource exhaustion. This behavior is particularly problematic in environments where memory and disk space are limited.
The attack vector is network-based, meaning an attacker can potentially exploit this vulnerability remotely without needing to be on the same local network. The attack complexity is low, as it does not require any special conditions or user interaction, making it easier for an attacker to exploit. Privileges required for exploitation are none, which heightens the risk even further.
In terms of impact, the availability impact is high, as the infinite loop will consume all available resources, leading to denial of service. There are no impacts on confidentiality or integrity, but the availability issues could have widespread effects, especially in production environments.
Risk & Impact Analysis
The real-world deployment risk associated with CVE-2021-28667 is significant, particularly for organizations that rely heavily on StackStorm for automation and orchestration tasks. The potential for an infinite loop to consume system resources can lead to severe service disruptions, impacting business operations and customer satisfaction.
Organizations need to consider the blast radius of this vulnerability. Given its nature, once triggered, it can affect all processes reliant on StackStorm, potentially bringing down entire services and workflows. The urgency to address this vulnerability is underscored by its high CVSS score and the fact that it can be exploited without authentication.
The assessment of urgency indicates that organizations should prioritize remediation efforts immediately. The potential for downtime and resource exhaustion presents a compelling case for swift action.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
All versions prior to vendor patch (3.4.1) are affected by CVE-2021-28667. Organizations should update to the latest version of StackStorm to mitigate this vulnerability.
Mitigation & Remediation
To remediate CVE-2021-28667, organizations should upgrade to StackStorm version 3.4.1 or later. If immediate patching is not feasible, consider implementing workarounds such as reviewing locale settings to ensure they are set to UTF-8 and avoiding logging of Unicode data until the patch can be applied.
Additionally, organizations should employ configuration hardening practices to reduce the attack surface and implement monitoring to detect any unusual resource usage patterns indicative of this vulnerability being exploited.
For further assistance, organizations may consider engaging in penetration testing services to validate their security posture.
Detection Guidance
Organizations should monitor logs for unusual patterns of resource consumption, particularly related to StackStorm processes. Look for any unexpected behavior or anomalies that may indicate exploitation attempts.
Network signatures can also help identify potential exploitation attempts. Implementing alerts for spikes in memory or disk usage related to StackStorm can provide early warning of this issue.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2021-28667 highlights the importance of robust handling of Unicode data in applications. Security teams should be aware of similar patterns that can lead to resource exhaustion vulnerabilities.
Organizations should consider adopting a proactive approach to security by implementing regular updates and security assessments. Engaging in penetration testing methodologies can help identify and remediate vulnerabilities before they can be exploited.
This incident serves as a reminder of the critical need for continuous security practices, including the implementation of vulnerability management programs that can adapt to evolving threats.
Ultimately, organizations must ensure they are not only reacting to known vulnerabilities but also actively seeking to understand and mitigate potential future threats.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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