CVE-2018-8795 in rdesktop
Summary
by MITRE
rdesktop versions up to and including v1.8.3 contain an Integer Overflow that leads to a Heap-Based Buffer Overflow in function process_bitmap_updates() and results in a memory corruption and probably even a remote code execution.
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Analysis
by VulDB Data Team • 07/06/2023
The vulnerability identified as CVE-2018-8795 represents a critical security flaw in rdesktop versions up to and including v1.8.3 that stems from an integer overflow condition within the process_bitmap_updates() function. This issue manifests as a heap-based buffer overflow that can potentially lead to remote code execution, making it a significant concern for systems utilizing this remote desktop protocol client. The vulnerability resides in the handling of bitmap update data during remote desktop connections, where improper input validation and arithmetic operations create conditions that allow malicious actors to manipulate memory structures.
The technical flaw occurs when the rdesktop client processes bitmap update data from a remote server, specifically within the process_bitmap_updates() function where integer overflow conditions can cause subsequent buffer overflow scenarios. When the application performs arithmetic operations on integer values representing bitmap dimensions or data sizes, an overflow can occur that results in a corrupted heap allocation. This heap corruption directly impacts the memory layout and can be exploited to overwrite critical memory regions, potentially allowing attackers to execute arbitrary code with the privileges of the affected process. The vulnerability is categorized under CWE-190 as an integer overflow condition that leads to a buffer overflow, which is a well-documented pattern in software security vulnerabilities.
The operational impact of this vulnerability extends beyond simple memory corruption, as it provides potential attackers with a pathway for remote code execution within the target system. When exploited successfully, an attacker could gain control over the rdesktop client process, potentially leading to complete system compromise depending on the privileges of the user running the client. The vulnerability affects all versions of rdesktop up to v1.8.3, making it a widespread concern for organizations that rely on this open-source remote desktop client for their network access needs. The nature of the flaw means that any remote desktop connection using vulnerable versions could be exploited, regardless of the specific remote server being accessed, as the vulnerability exists in the client-side processing logic.
Mitigation strategies for CVE-2018-8795 primarily focus on updating to patched versions of rdesktop, with version 1.8.4 and later providing the necessary fixes for the integer overflow and buffer overflow conditions. Organizations should prioritize immediate patching of all systems running vulnerable rdesktop versions, particularly those used in enterprise environments where remote access is prevalent. Additional defensive measures include implementing network segmentation to limit exposure, using network monitoring to detect anomalous remote desktop traffic patterns, and considering alternative remote access solutions that have been verified as free from similar vulnerabilities. From an ATT&CK framework perspective, this vulnerability maps to techniques involving remote code execution through software exploitation, specifically targeting client-side applications that handle remote data processing, making it relevant to tactics such as T1203 (Exploitation for Client Execution) and T1059 (Command and Scripting Interpreter) within the adversary lifecycle.