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Application & OT Security · Advanced

Symbolic Link Attack

Exploiting a privileged process that follows an attacker-created symbolic link to read or overwrite a protected file.

Definition

Often combined with TOCTOU in shared directories like /tmp. Mitigations include using secure temporary file APIs, O_NOFOLLOW flags, private temp directories and dropping privileges before file access.

Example

A root cron job writes to /tmp/out.log, which a user has linked to /etc/passwd.

Exam tip

Use mkstemp or similar secure temp file APIs.

Related terms