CVE-2018-8791 in rdesktop
Summary
by MITRE
rdesktop versions up to and including v1.8.3 contain an Out-Of-Bounds Read in function rdpdr_process() that results in an information leak.
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Analysis
by VulDB Data Team • 07/06/2023
The vulnerability CVE-2018-8791 represents a critical out-of-bounds read condition affecting rdesktop versions up to and including v1.8.3, specifically within the rdpdr_process() function. This flaw occurs during Remote Desktop Protocol client processing and demonstrates a classic memory safety issue that can lead to information disclosure. The vulnerability arises when the rdesktop client processes incoming RDP data streams without proper bounds checking on array accesses, creating opportunities for attackers to extract sensitive information from memory regions that should remain protected.
The technical implementation of this vulnerability involves the rdpdr_process() function failing to validate input data lengths before accessing memory buffers. When processing Remote Desktop Protocol data, the application does not adequately check array boundaries, allowing an attacker to craft malicious RDP packets that cause the client to read beyond allocated memory regions. This memory access violation can result in the exposure of sensitive data including session tokens, cryptographic keys, or other confidential information stored in adjacent memory locations. The flaw falls under CWE-125, which specifically addresses out-of-bounds read conditions, and represents a fundamental failure in input validation and memory management practices.
From an operational perspective, this vulnerability poses significant risks to organizations relying on rdesktop for remote desktop connections. An attacker positioned within the network or able to intercept RDP traffic can exploit this flaw to gain unauthorized access to memory contents that may contain authentication credentials, session state information, or other sensitive data. The information leak could potentially enable further attacks including credential theft, session hijacking, or privilege escalation within the compromised system. This vulnerability directly aligns with ATT&CK technique T1046, which covers network service scanning, and T1005, which involves data from local system, as it allows for information gathering through memory access violations.
The exploitation of CVE-2018-8791 requires minimal privileges and can be executed through standard network-based attacks against RDP connections. Organizations using rdesktop for remote access should immediately implement mitigation strategies including updating to patched versions, implementing network segmentation, and monitoring for suspicious RDP traffic patterns. The vulnerability also highlights the importance of proper input validation and bounds checking in network protocol implementations, emphasizing the need for defensive programming practices and regular security assessments of remote access tools. System administrators should consider alternative RDP clients that have been audited for similar memory safety issues and implement network-level controls to restrict RDP access to authorized users only.