Description

Improper link resolution before file access ('link following') in Windows Accessibility Infrastructure (ATBroker.exe) allows an authorized attacker to elevate privileges locally.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.8",
  "pubDate": "2026-08-11T17:18:10.597Z",
  "pubdate": "2026-08-11T17:18:10.597Z",
  "executiveSummary": "An improper link resolution before file access vulnerability, commonly known as link following, exists within the Windows Accessibility Infrastructure component specifically targeting ATBroker.exe. This vulnerability allows an authorized local attacker to elevate privileges on the affected system.\nThe flaw stems from insecure file handling practices where symbolic links or junction points are improperly resolved during file access operations performed by privileged processes. An attacker with local access and authorization to interact with the system can exploit this behavior to manipulate file system operations, forcing the application to read, write, or access files in unintended locations with elevated security contexts.\nThe primary impact of this vulnerability is local privilege escalation, potentially allowing an attacker to bypass standard operating system security controls, gain higher-level permissions such as SYSTEM access, and execute arbitrary code or modify sensitive system files. Successful exploitation requires the attacker to have prior local access to the target system and the ability to configure malicious file system constructs such as symbolic links prior to the privileged operation.\nOrganizations relying on the Windows Accessibility Infrastructure are at risk if local users can manipulate directory structures and influence ATBroker.exe execution flows. Mitigation requires applying official vendor patches as soon as they become available and adhering to secure file system hardening guidelines to restrict unauthorized link creation.",
  "technicalDetails": "The vulnerability is rooted in improper link resolution before file access, categorized under CWE-59. The affected component is ATBroker.exe, which resides within the Windows Accessibility Infrastructure. ATBroker.exe is responsible for facilitating communication between accessibility aids and the Windows desktop, often running with elevated privileges to manage system-wide accessibility features.\nThe root cause occurs when ATBroker.exe performs file I/O operations without adequately validating or securing the destination paths against pre-existing symbolic links, hard links, or directory junctions. When the privileged process attempts to access a file or directory based on predictable paths, it blindly follows the user-controllable link instead of safely resolving the underlying target. This race condition or TOCTOU (Time-of-Check to Time-of-Use) vector allows a lower-privileged process to redirect file operations.\nThe exploitation method involves a step-by-step attack flow executed by a locally authenticated adversary. First, the attacker identifies a file access operation performed by ATBroker.exe where the target path can be influenced or anticipated. Second, the attacker establishes a symbolic link or junction point in a directory writable by the attacker, pointing a benign-looking file path expected by ATBroker.exe to a sensitive system file or a restricted directory. Third, the attacker triggers the execution of ATBroker.exe or interacts with the accessibility infrastructure to initiate the vulnerable file access routine. Fourth, the privileged service follows the link, resulting in unintended file modification, arbitrary file creation, or unauthorized file disclosure.\nAuthentication and privilege requirements dictate that the attacker must already possess local interactive or programmatic access to the host operating system. Network exposure is non-existent, as the vulnerability cannot be exploited remotely. The payload behavior depends on the specific file operation hijacked, but typically culminates in privilege escalation by manipulating binaries, configuration files, or leveraging object persistence to compromise the security boundary between standard users and administrative domains. Post-exploitation impact includes full system compromise, persistence installation, and unauthorized access to protected local resources."
}