CVE-2021-1733 in Sysinternals PsExec
Summary
by MITRE • 02/26/2021
Sysinternals PsExec Elevation of Privilege Vulnerability
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 02/26/2021
The Sysinternals PsExec tool presents a significant elevation of privilege vulnerability that stems from improper access control mechanisms within its implementation. This vulnerability allows attackers to escalate their privileges from standard user level to administrative or SYSTEM level access, fundamentally compromising the security posture of targeted systems. The flaw specifically manifests when PsExec executes processes with elevated privileges without adequately validating the calling context or ensuring proper authorization boundaries are maintained during privilege escalation operations.
The technical root cause of this vulnerability lies in the insufficient validation of process execution contexts and the lack of proper privilege checking mechanisms within the tool's core execution engine. When PsExec is invoked to execute remote commands, it creates processes with elevated privileges but fails to properly verify whether the initiating user or process possesses the necessary authorization to perform such operations. This design flaw creates an attack surface where malicious actors can exploit the tool's legitimate functionality to bypass standard Windows security controls and gain unauthorized administrative access.
From an operational perspective, this vulnerability poses severe risks to enterprise environments as it enables attackers to leverage PsExec's widespread deployment across organizations for privilege escalation attacks. The vulnerability affects systems where PsExec is installed and used, particularly in environments where administrative accounts are commonly utilized or where the tool is part of standard IT management practices. Attackers can exploit this weakness by executing malicious code through PsExec with elevated privileges, potentially leading to complete system compromise, data exfiltration, or establishment of persistent backdoors.
The impact extends beyond individual system compromises as attackers can leverage this vulnerability to move laterally within networks where PsExec is deployed across multiple systems. Organizations that rely on PsExec for legitimate administrative tasks become vulnerable to supply chain attacks or insider threats, where compromised accounts can exploit the tool's privilege escalation capabilities. This vulnerability particularly affects environments with default installations of Sysinternals tools and systems where proper access controls have not been implemented to restrict PsExec usage.
Security professionals should implement multiple mitigations to address this vulnerability including restricting PsExec execution to authorized administrative users only, implementing network segmentation to limit access to systems running PsExec, and monitoring for unusual PsExec activities. The vulnerability aligns with CWE-284 which addresses improper access control, and relates to ATT&CK technique T1068 which covers privilege escalation through legitimate user tools. Organizations should also consider implementing application whitelisting policies that restrict execution of PsExec and other Sysinternals tools unless explicitly authorized.
Additional protective measures include regular auditing of PsExec usage patterns, implementing proper logging and monitoring for PsExec executions, and ensuring that administrative accounts are protected with strong authentication mechanisms including multi-factor authentication. The vulnerability demonstrates the importance of principle of least privilege implementation and highlights how legitimate administrative tools can become attack vectors when not properly secured and monitored. Security teams should also consider deploying endpoint detection and response solutions that can identify anomalous PsExec behavior indicative of exploitation attempts.
Organizations must recognize that this vulnerability represents a critical gap in their security posture, particularly in environments where privileged access is not properly controlled or where administrative tools are accessible to unauthorized users. The remediation approach should include comprehensive security awareness training for administrators regarding the risks associated with legitimate tools being weaponized by attackers, along with implementing proper network access controls and privilege management policies that limit exposure to such vulnerabilities.