Fundamental Flaw in File Monitoring APIs Exposes Keystrokes and App Activity Across Windows, Linux, Android, and macOS

Researchers from Graz University of Technology demonstrated how built-in file change notification mechanisms can leak sensitive user activity without requiring elevated privileges. The affected subsystems include inotify on Linux, FileObserver on Android, ReadDirectoryChangesW on Windows, and FSEvents on macOS. On Linux the technique enables reconstruction of typed text with 93-100% accuracy by monitoring /dev/input/event4 timestamps. Android apps can break sandbox isolation to observe messaging events, while Windows monitoring of browser cache files reveals visited websites at 97.8% accuracy. Only partial mitigations have been deployed in Linux and Windows, with no fixes available for Android or macOS. Additional attacks remain possible, including detection of password prompts to facilitate phishing overlays.

HabrTranslated from Russian

Read at source

Researchers from Graz University of Technology have published work showing how standard file-monitoring subsystems can be abused to leak private information across major operating systems.

The affected components are inotify in Linux, FileObserver in Android, ReadDirectoryChangesW in Windows, and FSEvents in macOS. These interfaces report when files are opened, modified, or deleted and can be accessed by unprivileged users who have directory-level permissions.

On Linux, access to the /dev/input directory allows an attacker to observe timestamped events from /dev/input/event4. By measuring intervals between keystrokes, researchers reconstructed typed text with accuracy between 93% and 100%. The attack also works over SSH sessions.

Android’s FileObserver breaks application isolation, enabling a malicious app to monitor messaging events such as document or media transfers in other applications.

In Windows, monitoring browser cache files revealed visited websites with 97.8% accuracy. On macOS the technique was less powerful but still exposed system events including audio device changes and Bluetooth updates.

Partial fixes appeared in Linux in December 2025 and an optional Windows policy was introduced, yet both remain insufficient. No patches exist for Android or macOS. Researchers also demonstrated an ongoing Linux attack that detects password prompts to overlay a fake login window.

Additional items reported this week include the MacSync infostealer for macOS that abuses iCloud infrastructure, a practical 1024-bit RSA factoring method, a flaw in the Muse AI assistant on macOS, a critical WordPress vulnerability affecting versions from 4.7 onward, an unpatched issue in Windows Defender, and zero-days in Citrix NetScaler and the D-Link DIR-822A router.

Meridian digestThe week's most consequential security stories, distilled into one briefing.See the digest

More in Vulnerabilities & Exploits

Telegram for Android Patches Voice Call Vulnerability Enabling Code Execution
Yandex Patches Millions of Stations After eMudhra Certificate Keys Compromised
Cisco ASA and FTD Face DoS Vulnerability in SSL VPN Already Exploited in the Wild