CVE-2021-41159 is a medium-severity vulnerability that affects all FreeRDP clients prior to version 2.4.1. This flaw allows malicious gateway connections to exploit improper input validation, potentially resulting in out-of-bounds memory writes. The vulnerability has been classified with a CVSS score of 5.8, indicating a medium risk to impacted systems. Organizations using affected FreeRDP versions should prioritize remediation to protect against possible exploitation.
Risk to organizations includes the potential for unauthorized access to sensitive data and system integrity compromise. Attackers may leverage this vulnerability to execute arbitrary code or manipulate system behavior if exploited successfully, especially in environments where FreeRDP is employed for remote desktop services.
Given the nature of this vulnerability, organizations should prioritize patching immediately. The issue has been resolved in FreeRDP version 2.4.1, and upgrading to this version or later is highly recommended to mitigate the associated risks.
For those unable to upgrade, it is advised to use alternative connection methods, such as `/gt:http` instead of `/gt:rpc`, or establish direct connections that bypass the gateway.
Vulnerability Details
The vulnerability stems from FreeRDP's failure to validate input data when using gateway connections, specifically those utilizing the `/gt:rpc` option. This oversight can enable a malicious gateway to write client memory out of bounds, leading to potential data corruption or arbitrary code execution.
The vulnerability is classified as CWE-787: Out-of-bounds Write, indicating a critical weakness in input validation that could be exploited by an attacker with network access. The vulnerability was published on October 21, 2021, and has since been modified to reflect its current status.
The affected products include FreeRDP versions prior to 2.4.1. Organizations using Fedora 35 or any distribution that includes vulnerable FreeRDP versions should take immediate action to remediate this vulnerability.
Technical Analysis
The root cause of CVE-2021-41159 is the improper validation of input data in FreeRDP when using gateway connections. The attack vector is network-based, allowing remote attackers to exploit this vulnerability without any physical access to the target system.
The attack complexity is considered high, as it requires an attacker to set up a malicious gateway that can intercept and manipulate the data being sent to the FreeRDP client. Additionally, high privileges are required for the attacker to exploit this vulnerability successfully.
User interaction is not required for the attack to be successful, which further increases the vulnerability's risk profile. In terms of impacts, the confidentiality impact is none, while the integrity impact is high, suggesting that an attacker could modify data within the client environment. The availability impact is none.
Risk & Impact Analysis
The deployment of vulnerable FreeRDP clients presents a significant risk, especially in environments that utilize remote desktop services for critical operations. The potential blast radius includes exposure of sensitive data and the ability for attackers to execute arbitrary commands or manipulate client sessions.
Organizations should assess their usage of FreeRDP and prioritize immediate remediation actions to mitigate the risks associated with this vulnerability. Given the CVSS score of 5.8, it is advisable to address this vulnerability during the next patch cycle or as part of an emergency remediation process.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
All FreeRDP clients prior to version 2.4.1 are affected by this vulnerability. Additionally, Fedora 35 has been identified as a platform using vulnerable FreeRDP versions, necessitating immediate action for users of this distribution.
Mitigation & Remediation
Organizations should upgrade to FreeRDP version 2.4.1 or later to ensure that this vulnerability is resolved. In cases where immediate upgrading is not feasible, it is recommended to use the `/gt:http` connection option instead of `/gt:rpc`, or establish direct connections to avoid using a gateway.
For additional information on secure connection practices and vulnerability management, organizations may consider engaging in penetration testing services tailored to their specific IT environment.
Detection Guidance
Organizations should monitor logs for any unusual access patterns or errors related to FreeRDP connections. Specific indicators include unexpected memory access patterns and anomalies in client behavior that may suggest exploitation attempts.
AppSecure Threat Intelligence Insight
CVE-2021-41159 illustrates ongoing challenges in maintaining secure remote desktop implementations. Security teams should be aware of similar vulnerabilities that may arise in the future and ensure robust validation mechanisms are in place. This incident serves as a reminder of the importance of regular software updates and proactive vulnerability management.
For comprehensive security assessments, organizations may refer to strategies outlined in the penetration testing methodology and engage in continuous security testing practices.
Understanding the implications of vulnerabilities like CVE-2021-41159 can empower security teams to implement more effective defenses, fostering a resilient IT environment.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
.webp)