Integer Overflow in FreeRDP Leading to Heap Buffer Overflow

Executive Summary

This vulnerability is an integer overflow in FreeRDP clients on 32-bit builds prior to version 3.28.0. It occurs in the function update_read_delta_points within the libfreerdp/core/orders.c file. When the software multiplies an attacker-controlled point count by the size of a DELTA_POINT structure without proper validation, the multiplication can overflow. This causes the program to allocate a heap buffer that is smaller than intended.

Because the buffer is undersized, subsequent writes during initialization can overflow the buffer, leading to heap memory corruption. This flaw allows a malicious Remote Desktop Protocol (RDP) peer to exploit the vulnerability by sending specially crafted data.

The issue was fixed in FreeRDP version 3.28.0 by correcting the overflow guard logic to properly check the multiplication size before allocation.

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Impact Analysis

Exploitation of this vulnerability can lead to several serious impacts. Because the heap buffer overflow allows writing beyond allocated memory, an attacker could cause a client crash or denial of service.

More critically, depending on the heap layout, an attacker might achieve arbitrary code execution on the affected system. This means the attacker could potentially run malicious code with the privileges of the FreeRDP client.

Since the vulnerability is remotely exploitable by a malicious RDP peer without requiring privileges or user interaction, it poses a high security risk.

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Mitigation Strategies

To mitigate this vulnerability, you should upgrade FreeRDP clients to version 3.28.0 or later, where the integer overflow issue in update_read_delta_points has been fixed.

The fix involves a corrected overflow guard that properly validates the multiplication of the attacker-controlled point count by sizeof(DELTA_POINT) before memory allocation, preventing heap buffer overflow.

Until the upgrade is applied, consider restricting or monitoring RDP traffic from untrusted sources to reduce the risk of exploitation.

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Compliance Impact

The provided context and resources do not contain information regarding the impact of this vulnerability on compliance with common standards and regulations such as GDPR or HIPAA.

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