CVE-2021-31810 is a medium-severity vulnerability that affects multiple versions of Ruby, specifically through 2.6.7, 2.7.x through 2.7.3, and 3.x through 3.0.1. This vulnerability allows a malicious FTP server to utilize the PASV response to trick the Net::FTP library into connecting back to a specified IP address and port. Consequently, this behavior may enable attackers to extract sensitive information about services that are generally private, including conducting port scans and service banner extractions.
The CVSS score for this vulnerability is 5.8, indicating a medium level of severity. The attack vector for this vulnerability is classified as NETWORK, with a low attack complexity and no privileges required for exploitation. The potential impacts include a low confidentiality impact, with no integrity or availability impact.
Risk to organizations includes the possibility of unauthorized access to sensitive data due to the exploitable nature of this vulnerability. Attackers may leverage this vulnerability to scan for open ports and identify services running on affected systems. Organizations should prioritize patching this vulnerability to mitigate the associated risks.
Organizations should address this vulnerability in their priority patch cycle, given its potential impact and the current availability of exploits.
Vulnerability Details
The vulnerability was disclosed on July 13, 2021, and is classified under CWE as 'Other'. The affected products include Ruby, Debian Linux, and JD Edwards EnterpriseOne Tools. The publication date of the vulnerability is confirmed, and it has been marked as modified due to ongoing assessments.
Technical Analysis
The root cause of CVE-2021-31810 lies in how the Net::FTP library handles PASV responses from FTP servers. When a malicious server responds with a PASV command, it can redirect the connection to an arbitrary IP and port, potentially leading to unauthorized information disclosure. The attack vector is network-based, requiring no user interaction, and operates with low complexity. As such, anyone with network access to the vulnerable Ruby installation can exploit this vulnerability.
Risk & Impact Analysis
Organizations that deploy Ruby in their applications face significant risks from this vulnerability. The ability for an attacker to execute port scans and gather information about services that are typically private poses a substantial threat to the confidentiality of sensitive data. The urgency for remediation is heightened due to the nature of the attack, which is straightforward and requires minimal resources. Given the CVSS score of 5.8, organizations should prioritize patching this vulnerability immediately to prevent potential exploitation.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The affected versions of Ruby are those prior to 2.6.8, including 2.6.7, 2.7.0 to 2.7.3, and 3.0.0 to 3.0.1. Additionally, Debian Linux version 9.0 and JD Edwards EnterpriseOne Tools prior to version 9.2.6.1 are also impacted by this vulnerability.
Mitigation & Remediation
Organizations should implement the following mitigations to address CVE-2021-31810: Apply necessary patches or updates for Ruby and associated components as soon as possible. If immediate patching is not feasible, consider implementing configuration hardening and network controls to restrict access to the impacted services. Additionally, organizations should monitor for unusual activity indicative of exploitation attempts.
Detection Guidance
Organizations should monitor logs for indicators of exploitation attempts, including unusual outbound connections initiated by the Net::FTP library. Behavioral anomalies in application traffic should also be noted, particularly connections to unexpected IP addresses or ports.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2021-31810 highlights the need for robust input validation and secure handling of external responses in network protocols. This vulnerability exemplifies how even minor misconfigurations can lead to significant security risks. Security teams should take this as an opportunity to review their network security posture and ensure proper validation mechanisms are in place to prevent similar vulnerabilities. Organizations are encouraged to conduct regular security assessments, such as application security assessments and continuous monitoring to identify and remediate vulnerabilities proactively.
Incorporating a continuous penetration testing strategy is essential to stay ahead of emerging threats and vulnerabilities.
Furthermore, organizations should consider establishing a red teaming program to simulate real-world attacks and evaluate their security defenses in a controlled environment.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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