CVE-2018-20182 in rdesktop
Summary
by MITRE
rdesktop versions up to and including v1.8.3 contain a Buffer Overflow over the global variables in the function seamless_process_line() that results in memory corruption and probably even a remote code execution.
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Analysis
by VulDB Data Team • 08/01/2023
The vulnerability identified as CVE-2018-20182 represents a critical buffer overflow flaw within rdesktop versions up to and including v1.8.3. This issue manifests within the seamless_process_line() function where global variables become susceptible to overflows, creating a pathway for memory corruption that could potentially enable remote code execution. The vulnerability arises from inadequate input validation and bounds checking mechanisms within the remote desktop protocol client implementation.
The technical exploitation of this buffer overflow occurs when processing specific input data within the seamless desktop functionality of rdesktop. The flaw exists in how the software handles data processing in the seamless_process_line() function, where global variables are manipulated without proper boundary checks. This allows an attacker to craft malicious input that exceeds the allocated buffer space, leading to memory corruption that can be leveraged to overwrite critical memory locations including return addresses and function pointers. The vulnerability falls under CWE-121, which specifically addresses stack-based buffer overflow conditions, and potentially CWE-122 for heap-based buffer overflows depending on the exact memory layout during exploitation.
From an operational perspective, this vulnerability poses significant risks to organizations relying on rdesktop for remote access solutions. The potential for remote code execution means that attackers could gain full system control of affected machines without requiring local access or authentication. This makes the vulnerability particularly dangerous in enterprise environments where remote desktop access is commonly used for administrative tasks, as it could allow attackers to escalate privileges and move laterally within networks. The impact extends beyond individual system compromise to potentially enable broader network infiltration and data exfiltration capabilities.
The exploitation of CVE-2018-20182 aligns with ATT&CK techniques related to remote service exploitation and privilege escalation. Attackers could leverage this vulnerability through remote desktop connections, using techniques such as command and control communication to establish persistent access. The vulnerability's classification as a remote code execution flaw places it within ATT&CK's T1059 (Command and Scripting Interpreter) and T1075 (Remote Services) tactics, enabling attackers to execute arbitrary code on compromised systems. Organizations using rdesktop for remote access should consider implementing network segmentation and access controls to limit potential attack surfaces.
Mitigation strategies for CVE-2018-20182 primarily involve immediate software updates to versions that address the buffer overflow vulnerability. System administrators should prioritize patching affected rdesktop installations to the latest stable releases that contain proper bounds checking and input validation. Additionally, network-based mitigations such as firewall rules restricting remote desktop access to trusted networks, implementing multi-factor authentication, and deploying intrusion detection systems can help reduce the risk of exploitation. Organizations should also consider implementing application whitelisting policies to prevent execution of unpatched versions of rdesktop. The vulnerability demonstrates the importance of maintaining up-to-date remote access software and implementing robust security practices to protect against memory corruption vulnerabilities that could lead to complete system compromise.