CVE-2022-26488 in Python
Summary
by MITRE • 03/10/2022
In Python before 3.10.3 on Windows, local users can gain privileges because the search path is inadequately secured. The installer may allow a local attacker to add user-writable directories to the system search path. To exploit, an administrator must have installed Python for all users and enabled PATH entries. A non-administrative user can trigger a repair that incorrectly adds user-writable paths into PATH, enabling search-path hijacking of other users and system services. This affects Python (CPython) through 3.7.12, 3.8.x through 3.8.12, 3.9.x through 3.9.10, and 3.10.x through 3.10.2.
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Analysis
by VulDB Data Team • 03/12/2022
This vulnerability represents a critical privilege escalation flaw in Python installations on Windows systems, specifically affecting versions prior to 3.10.3. The issue stems from inadequate security measures in the Python installer's handling of system search paths, creating a persistent vector for local attackers to elevate their privileges. The vulnerability operates through a sophisticated attack chain that begins with the installation configuration and extends to the exploitation of path manipulation weaknesses within the Windows operating system. The flaw is particularly dangerous because it leverages legitimate system installation processes to create persistent backdoors for privilege escalation, making it difficult to detect and remediate through standard security measures.
The technical implementation of this vulnerability involves the manipulation of the Windows PATH environment variable during Python installation processes. When Python is installed for all users with PATH entries enabled, the installer creates conditions where user-writable directories can be inadvertently added to the system search path. This occurs because the installation process does not properly validate or secure the PATH modification steps, allowing attackers to exploit this weakness during routine system maintenance operations. The vulnerability specifically targets the repair functionality of Python installations, where a non-administrative user can trigger a repair process that incorrectly modifies the PATH variable to include user-writable directories. This creates a persistent state where subsequent system operations may execute malicious code from these compromised locations, effectively enabling attackers to hijack legitimate system processes and services.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass broader system compromise and persistent access. Attackers can leverage this weakness to establish long-term presence on compromised systems, as the modified PATH entries remain active across system reboots and user sessions. The vulnerability affects multiple Python version streams including 3.7.12, 3.8.12, 3.9.10, and 3.10.2, indicating a widespread exposure across the Python ecosystem. This affects not only individual user systems but also enterprise environments where Python installations are common across multiple user accounts and system services. The vulnerability's impact is particularly severe in enterprise environments where administrators may have installed Python for all users, creating widespread exposure across entire organizations. System services and applications that rely on Python components become vulnerable to attack, potentially leading to complete system compromise and data exfiltration.
Security mitigations for this vulnerability should focus on immediate installation updates and path validation measures. Organizations must prioritize updating to Python 3.10.3 or later versions where this vulnerability has been addressed through enhanced PATH validation during installation processes. System administrators should implement strict PATH management policies and regularly audit system search paths to identify unauthorized modifications. The recommended approach includes disabling automatic PATH modifications during installation, implementing secure installation procedures, and conducting regular security assessments of system PATH configurations. Additionally, organizations should consider implementing application whitelisting controls and monitoring for suspicious PATH modifications to prevent exploitation. This vulnerability aligns with CWE-426 and CWE-78 security weaknesses, representing a path manipulation issue that enables privilege escalation through insecure installation processes. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques and persistence mechanisms, specifically targeting the PATH environment variable as a means of maintaining access and executing malicious code with elevated privileges.