CVE-2017-6356 in Terminal Services Agent
Summary
by MITRE
Palo Alto Networks Terminal Services (aka TS) Agent 6.0, 7.0, and 8.0 before 8.0.1 uses weak permissions for unspecified resources, which allows attackers to obtain sensitive session information via unknown vectors.
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Analysis
by VulDB Data Team • 09/10/2020
The vulnerability identified as CVE-2017-6356 affects Palo Alto Networks Terminal Services Agent versions 6.0, 7.0, and 8.0 before 8.0.1, representing a critical security weakness in the authentication and authorization mechanisms of the terminal services component. This issue stems from the improper configuration of file and resource permissions within the agent software, creating an exploitable condition that undermines the security posture of systems relying on these services. The vulnerability falls under the category of privilege escalation and information disclosure, as attackers can leverage weak permissions to access sensitive session data that should remain protected. The unspecified nature of the affected resources suggests that multiple components within the Terminal Services Agent may be vulnerable to unauthorized access, potentially including session tokens, authentication credentials, or other confidential information exchanged during terminal sessions.
The technical flaw manifests through inadequate permission controls that allow unauthorized users or processes to access resources that should be restricted to legitimate administrators or authenticated sessions. This weakness creates an attack surface where malicious actors can potentially obtain session information without proper authentication, enabling them to impersonate legitimate users or intercept sensitive communications. The vulnerability represents a failure in the principle of least privilege, where resources are not properly protected with appropriate access controls and permissions. From a cybersecurity perspective, this issue aligns with CWE-276, which addresses improper permissions for critical resources, and can be classified as a privilege escalation vulnerability that allows attackers to gain unauthorized access to sensitive information.
The operational impact of this vulnerability is significant as it compromises the integrity and confidentiality of terminal services sessions within Palo Alto Networks environments. Attackers who successfully exploit this weakness can potentially gain access to session tokens, user credentials, or other sensitive information that could be used for further attacks within the network. The vulnerability is particularly concerning in enterprise environments where terminal services are commonly used for remote administration and access to critical systems. The attack vector remains unspecified, which suggests that the exploitation could occur through multiple pathways including local access, network-based attacks, or through other compromised systems within the network infrastructure. This ambiguity in attack methods increases the potential risk as defenders must consider various exploitation scenarios when implementing mitigations.
Organizations utilizing affected Palo Alto Networks Terminal Services Agent versions face substantial risk of credential theft, session hijacking, and potential lateral movement within their networks. The vulnerability can be leveraged by attackers to establish persistent access to systems through stolen session information, potentially enabling them to maintain unauthorized access over extended periods. Security professionals should consider this vulnerability in the context of the ATT&CK framework, particularly under techniques related to credential access and privilege escalation. The most effective mitigation strategy involves updating to Palo Alto Networks Terminal Services Agent version 8.0.1 or later, which includes the necessary permission fixes and access control improvements. Additionally, organizations should conduct comprehensive permission audits of their terminal services components, implement proper monitoring for unauthorized access attempts, and ensure that all systems are regularly updated with the latest security patches to prevent exploitation of similar vulnerabilities in the future.