CVE-2022-24986

What it actually does

Insecure reuse of a predictable temporary filename in /tmp during KCron editing sessions creates a time-of-check-to-time-of-use race condition that allows an attacker to replace the file contents between creation and execution.

Why it matters to the business

Local users can gain the ability to execute arbitrary commands with the privileges of the KCron process owner, potentially leading to full system compromise on multi-user Linux desktops or servers that rely on this cron editor.

How an attack unfolds

An attacker with local access monitors /tmp for the initial creation of the KCron temporary file, records its name, then prepares a symlink or malicious replacement file with the same name; on the next save operation within the same editing session the malicious file is consumed and its commands are scheduled.

How to fix it

Upgrade KDE KCron to a version that uses secure temporary file handling such as mkstemp or a private directory; if no updated package is available, replace KCron with an alternative cron editor that avoids predictable /tmp filenames.

How to confirm the fix worked

Inspect the KCron source or running process to confirm temporary files are created with mkstemp or O_EXCL flags and are placed outside world-writable directories; test by attempting concurrent file creation with the same name.

Typical attack path

1. Obtain local user access on the target system
2. Monitor /tmp directory for KCron temporary file creation events
3. Capture the exact filename used in the first save
4. Create a symlink or malicious file using the captured name before the next edit
5. Trigger or wait for the user to perform a subsequent save in KCron
6. Verify the attacker-controlled commands have been added to the crontab

How to detect it

Search system logs and file creation events in /tmp for repeated or predictable filenames matching KCron session patterns; examine crontab entries added during active editing sessions for unexpected commands.

What your security team should do

• Remove or restrict local interactive access for untrusted users on systems running KCron
• Audit all systems for presence of KDE KCron and schedule replacement with a maintained cron editor
• Enable filesystem monitoring on /tmp to alert on unexpected file creation by cron-related processes
• Review existing crontabs for any unauthorized entries that may indicate prior exploitation