CVE-2018-8793 in rdesktop
Summary
by MITRE
rdesktop versions up to and including v1.8.3 contain a Heap-Based Buffer Overflow in function cssp_read_tsrequest() that 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-2018-8793 represents a critical heap-based buffer overflow flaw within the rdesktop remote desktop protocol client software. This issue affects all versions up to and including rdesktop version 1.8.3, making it a significant concern for organizations relying on remote desktop connectivity. The vulnerability manifests specifically within the cssp_read_tsrequest() function, which processes incoming data during the RDP connection establishment phase. This function fails to properly validate the size of incoming data structures, creating an exploitable condition where maliciously crafted input can exceed the allocated buffer boundaries.
The technical nature of this vulnerability places it squarely within the CWE-122 category of heap-based buffer overflow, which occurs when a program writes more data to a heap-allocated buffer than it can hold. In the context of rdesktop, this flaw allows an attacker to manipulate memory layout and potentially execute arbitrary code on the target system. The memory corruption resulting from this overflow can lead to unpredictable behavior including application crashes, data corruption, or more critically, complete system compromise. The vulnerability's remote exploitability means that an attacker need not have physical access to the target system, as the flaw can be triggered through network-based attacks during the RDP connection process.
The operational impact of CVE-2018-8793 extends beyond simple service disruption to encompass potential full system compromise. Organizations utilizing rdesktop for remote administration face significant risk as attackers could leverage this vulnerability to gain unauthorized access to sensitive systems. The attack surface is particularly concerning given that RDP is commonly used for administrative access to corporate networks, making this vulnerability a prime target for attackers seeking persistent access. The flaw's presence in rdesktop versions up to 1.8.3 indicates that it has been present for several years, suggesting that many systems may remain unpatched and vulnerable to exploitation. This vulnerability aligns with ATT&CK technique T1021.001 for remote services and T1059.007 for command and scripting interpreter, as exploitation would likely involve remote code execution and command injection.
Mitigation strategies for CVE-2018-8793 primarily focus on immediate patching and system hardening. Organizations should upgrade to rdesktop versions 1.8.4 or later, where the buffer overflow has been addressed through proper input validation and bounds checking. Network segmentation and access control measures should be implemented to limit exposure of rdesktop services to untrusted networks. Additional protective measures include disabling unnecessary RDP services, implementing strong authentication mechanisms, and monitoring for suspicious network activity. Security teams should also consider deploying intrusion detection systems capable of identifying exploitation attempts targeting this specific vulnerability. The remediation process should include thorough vulnerability scanning to identify all potentially affected systems and comprehensive testing of the updated software to ensure compatibility with existing network infrastructure.