CVE-2021-21598 in Wyse ThinOS
Summary
by MITRE • 08/11/2021
Dell Wyse ThinOS, versions 9.0, 9.1, and 9.1 MR1, contain a Sensitive Information Disclosure Vulnerability. An authenticated attacker with physical access to the system could exploit this vulnerability to read sensitive Smartcard data in log files.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 08/15/2021
The vulnerability CVE-2021-21598 affects Dell Wyse ThinOS operating systems in versions 9.0, 9.1, and 9.1 MR1, representing a critical sensitive information disclosure flaw that significantly impacts system security. This vulnerability specifically targets the handling of sensitive data within system log files, creating a potential pathway for unauthorized data exposure that could compromise the integrity of authentication mechanisms relying on smartcard technology. The flaw manifests when an authenticated attacker with physical access to the target system can exploit the improper logging practices to extract confidential smartcard information, thereby undermining the security model designed to protect sensitive authentication credentials.
The technical root cause of this vulnerability lies in the inadequate sanitization and handling of sensitive data within the logging subsystem of Dell Wyse ThinOS. When smartcard authentication processes occur within the system, the relevant sensitive information is being written to log files without proper obfuscation or encryption mechanisms. This design flaw creates a persistent exposure window where smartcard data, including authentication tokens and cryptographic keys, becomes accessible through log file examination. The vulnerability aligns with CWE-200, which addresses the improper handling of sensitive information, and represents a classic example of insecure logging practices that violate fundamental security principles. The issue is particularly concerning because it requires only physical access and authentication credentials to exploit, making it accessible to attackers who may already have legitimate access to the system.
The operational impact of CVE-2021-21598 extends beyond simple data exposure, as it fundamentally undermines the trust model of smartcard-based authentication systems. When smartcard data becomes accessible through log files, attackers can potentially reconstruct authentication tokens, extract cryptographic keys, or perform credential replay attacks against other systems that may trust the compromised smartcard credentials. This vulnerability creates a persistent threat vector that remains active as long as the vulnerable ThinOS versions remain deployed, potentially enabling lateral movement within networks where smartcard authentication is utilized. The risk is amplified by the fact that log files are often retained for extended periods, creating long-term exposure windows for sensitive information. This vulnerability also aligns with ATT&CK technique T1070.004, which covers the use of log data for credential access, and represents a significant weakening of the security boundary that smartcard authentication is designed to establish.
Organizations utilizing Dell Wyse ThinOS systems must implement immediate mitigation strategies to address this vulnerability, including applying the vendor-provided security patches and updates as soon as they become available. System administrators should also conduct comprehensive log file audits to identify any instances where sensitive information may have been previously exposed, and implement enhanced log sanitization procedures to prevent future occurrences. The mitigation approach should include configuration changes to ensure that sensitive data is properly masked or encrypted within log files, and that access controls are strengthened to limit who can read system logs. Additionally, organizations should consider implementing automated monitoring solutions that can detect and alert on suspicious log file access patterns, as well as establish regular security assessments to identify similar vulnerabilities within their thin client infrastructure. The vulnerability underscores the importance of proper data handling practices in security-critical systems and highlights the need for comprehensive security testing of logging mechanisms within embedded operating systems.