FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.20.1, a global-buffer-overflow vulnerability was observed in FreeRDP's Base64 decoding path. The root cause appears to be implementation-defined char signedness: on Arm/AArch64 builds, plain char is treated as unsigned, so the guard c <= 0 can be optimized into a simple c != 0 check. As a result, non-ASCII bytes (e.g., 0x80-0xFF) may bypass the intended range restriction and be used as an index into a global lookup table, causing out-of-bounds access.
This vulnerability has a CVSS score of 5.6, classifying it as medium severity. The potential risk to organizations includes unauthorized access to system memory, which could lead to information disclosure or system instability. Given the nature of this vulnerability and its potential impacts, organizations should prioritize patching immediately.
As of now, there is no public exploit confirmed for this vulnerability. It is essential for defenders to stay informed about vulnerabilities in widely used software like FreeRDP due to the potential for exploitation in the wild.
Organizations should address this vulnerability in their priority patch cycle, ensuring that all systems running affected versions of FreeRDP are updated to version 3.20.1 or later.
Vulnerability Details
The official CVE description identifies the global-buffer-overflow vulnerability caused by improper handling of character signedness. The vulnerability type is classified under CWE-125: Out-of-bounds Read and CWE-758: Improperly Initialized Variable.
The CVSS score of 5.6 indicates a medium severity level, with an attack vector of NETWORK and high attack complexity. There are no privileges required or user interactions needed to exploit this vulnerability, underscoring its significance.
Technical Analysis
The root cause of this vulnerability is the implementation-defined char signedness in FreeRDP's Base64 decoding path. On Arm/AArch64 builds, the use of plain char can lead to situations where non-ASCII bytes are mishandled, allowing them to be used as indices into a global lookup table. This results in out-of-bounds access, which can ultimately compromise the integrity and availability of the system.
The attack vector is network-based, and the complexity is categorized as high due to the requirement for specific character input that may not be trivial for an attacker to craft. No privileges are required, and no user interaction is necessary to exploit this vulnerability.
Risk & Impact Analysis
The real-world risk associated with this vulnerability is significant, particularly for organizations utilizing FreeRDP in their infrastructure. Attackers may leverage this vulnerability to gain unauthorized access to sensitive information or disrupt service availability.
The potential blast radius of exploitation could affect not only individual systems but also interconnected services that rely on FreeRDP for remote access. Organizations are advised to assess their exposure and act accordingly.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
All versions of FreeRDP prior to 3.20.1 are affected by this vulnerability. It is crucial to verify the version in use and upgrade to 3.20.1 or later to mitigate risks.
Mitigation & Remediation
To effectively mitigate this vulnerability, organizations should upgrade FreeRDP to version 3.20.1 or later. If an immediate upgrade is not feasible, organizations should consider implementing network controls to limit access to vulnerable systems and monitor for unusual activity.
Organizations can also benefit from conducting a thorough security assessment to identify any additional vulnerabilities that may exist and apply appropriate remediation measures. For more information on effective security practices, organizations may refer to relevant resources or consult with security professionals.
Detection Guidance
Organizations should monitor logs for any indicators of exploit attempts related to FreeRDP, particularly focusing on unusual Base64 inputs that may indicate a probing attack.
Behavioral anomalies in network traffic can also serve as a critical indicator of potential exploitation. Implementing network signatures to detect anomalous requests could help in early detection.
AppSecure Threat Intelligence Insight
This vulnerability underscores the importance of secure coding practices and the need for regular updates in software development. It represents a pattern of vulnerabilities related to improper input handling, which continue to be a common source of security issues.
Security teams are encouraged to proactively assess their systems for similar vulnerabilities and to implement measures that enhance input validation and buffer management.
Penetration testing can also aid in identifying and remediating vulnerabilities before they can be exploited.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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