CVE-2019-0693 in Windows
Summary
by MITRE
An elevation of privilege vulnerability exists due to an integer overflow in Windows Subsystem for Linux, aka 'Windows Subsystem for Linux Elevation of Privilege Vulnerability'. This CVE ID is unique from CVE-2019-0682, CVE-2019-0689, CVE-2019-0692, CVE-2019-0694.
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Analysis
by VulDB Data Team • 08/01/2023
The vulnerability identified as CVE-2019-0693 represents a critical elevation of privilege flaw within the Windows Subsystem for Linux (WSL) component of Microsoft Windows operating systems. This vulnerability specifically exploits an integer overflow condition that occurs during the processing of certain system calls or memory operations within the WSL environment. The flaw exists in the kernel-level components that manage the interaction between Windows and the Linux subsystem, creating a pathway for malicious actors to escalate their privileges from standard user level to administrative access. The integer overflow manifests when the subsystem processes data structures that exceed the maximum value that can be represented by the integer type, leading to unpredictable behavior and potential code execution opportunities. This vulnerability is particularly concerning because it operates at the core of the operating system's privilege management mechanisms, where a single flaw can compromise the entire security posture of a system.
The technical implementation of this vulnerability involves a specific integer overflow condition that occurs within the WSL subsystem's memory management routines. When legitimate user processes attempt to manipulate certain data structures or perform operations that involve integer arithmetic, the subsystem fails to properly validate the results of these operations, allowing for values to wrap around or exceed their allocated storage limits. This overflow condition can be exploited by an attacker to manipulate memory layout, overwrite critical system structures, or bypass access control mechanisms. The flaw is classified under CWE-190, which specifically addresses integer overflow conditions, and represents a classic example of how improper input validation can lead to privilege escalation attacks. The vulnerability affects Windows 10 versions prior to the security updates released in April 2019, with particular emphasis on systems running WSL version 1. The attack vector requires local user access and can be executed through carefully crafted system calls that trigger the integer overflow condition.
The operational impact of CVE-2019-0693 extends beyond simple privilege escalation, as it fundamentally undermines the security model of the Windows operating system when WSL is enabled. An attacker who successfully exploits this vulnerability can gain full administrative control over the affected system, potentially leading to data exfiltration, system compromise, or deployment of additional malicious software. The implications are particularly severe in enterprise environments where WSL might be enabled for development or compatibility purposes, as it provides attackers with a potential foothold for lateral movement within the network. The vulnerability's exploitation can also enable persistence mechanisms, allowing attackers to maintain access even after system reboots. From a threat actor perspective, this vulnerability aligns with ATT&CK technique T1068, which covers 'Exploitation for Privilege Escalation', and demonstrates how seemingly isolated subsystem vulnerabilities can provide significant attack surface expansion. Organizations running affected versions of Windows 10 are particularly at risk, as the vulnerability can be exploited without requiring network connectivity or specialized tools beyond those available to standard user accounts.
Mitigation strategies for CVE-2019-0693 primarily focus on applying the appropriate security updates released by Microsoft, which address the integer overflow condition through proper input validation and boundary checking mechanisms. System administrators should immediately deploy the April 2019 security updates for Windows 10, specifically targeting the WSL subsystem components. Organizations should also implement the principle of least privilege, ensuring that WSL is only enabled when absolutely necessary for business operations, and that user accounts have minimal required permissions. Additional protective measures include monitoring for unusual system behavior or unauthorized privilege escalation attempts, implementing network segmentation to limit the potential impact of successful exploitation, and maintaining current antivirus signatures that can detect exploitation attempts. The vulnerability serves as a reminder of the importance of comprehensive security testing for subsystems and the need for continuous monitoring of all components within modern operating systems. Security teams should also consider implementing automated patch management solutions to ensure timely deployment of security updates across all affected systems, as the integer overflow condition could potentially be exploited in combination with other vulnerabilities to create more sophisticated attack vectors.