CVE-2015-7244 in MobaXterm
Summary
by MITRE
The default configuration of the server in MobaXterm before 8.3 has a disabled Access Control setting and consequently does not require authentication for X11 connections, which allows remote attackers to execute arbitrary commands or obtain sensitive information via X11 packets.
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Analysis
by VulDB Data Team • 11/10/2024
The vulnerability identified as CVE-2015-7244 affects MobaXterm versions prior to 8.3, specifically targeting the default server configuration that disables access control mechanisms for X11 connections. This represents a critical security flaw that fundamentally undermines the authentication requirements necessary to protect graphical network services. The issue stems from the software's default configuration where X11 forwarding capabilities are exposed without proper authentication barriers, creating an attack surface that remote adversaries can exploit to gain unauthorized access to the system's graphical interface components.
The technical flaw manifests through the improper handling of X11 access control settings within the MobaXterm server implementation. X11 forwarding allows users to run graphical applications on remote systems while displaying them locally, but this functionality requires strict authentication controls to prevent unauthorized access. When access control is disabled, the X11 server accepts connections from any remote host without verifying credentials or access permissions, effectively bypassing the security model that should protect against unauthorized graphical session access. This vulnerability directly maps to CWE-284, which addresses improper access control issues in software implementations, and represents a classic example of insufficient privilege checking in network services.
The operational impact of this vulnerability extends far beyond simple unauthorized access to graphical interfaces. Remote attackers who exploit this weakness can execute arbitrary commands on the affected system through carefully crafted X11 packets, potentially leading to complete system compromise. The ability to obtain sensitive information through X11 connections means that attackers can intercept graphical data, access session information, and potentially escalate privileges within the compromised environment. This vulnerability particularly affects environments where MobaXterm is used for remote administration, as it provides attackers with a path to execute malicious code without requiring legitimate credentials or network-level authentication, making it especially dangerous in enterprise settings where graphical remote access is commonly utilized.
The attack vector for CVE-2015-7244 follows the patterns defined in the MITRE ATT&CK framework under the T1071.004 technique for application layer protocol usage, specifically targeting X11 traffic. Attackers can leverage this vulnerability by establishing X11 connections to the vulnerable MobaXterm server, bypassing traditional authentication mechanisms that would normally prevent unauthorized access. The exploitation process typically involves connecting to the X11 server port and sending malicious X11 protocol packets that can trigger command execution or information disclosure. This vulnerability also aligns with ATT&CK technique T1068, which covers local privilege escalation through the exploitation of insecure configurations, as the default settings create an insecure foundation that allows for unauthorized access to system resources. Organizations should implement immediate mitigations including updating to MobaXterm version 8.3 or later, enabling proper access control settings, and reviewing network configurations to restrict access to X11 ports. Additionally, network segmentation and firewall rules should be implemented to limit access to X11 services to trusted networks only, reducing the attack surface and preventing unauthorized exploitation of this authentication bypass vulnerability.