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Potential Copy Fail (CVE-2026-31431) Exploitation via AF_ALG Socket

Correlates a burst of non-root AF_ALG-class "socket", "splice", or "bound-socket" telemetry with a subsequent process execution where effective user is root but the login user remains non-root. This sequence matches…

Description

Correlates a burst of non-root AF_ALG-class "socket", "splice", or "bound-socket" telemetry with a subsequent process execution where effective user is root but the login user remains non-root. This sequence matches common post-exploitation chains for Copy Fail (CVE-2026-31431) style abuse where AF_ALG and "splice" primitives precede executing a corrupted setuid binary from cache.

Detection logic

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Detection requirements

Platform
ContainersIaaSIdentity ProviderLinuxmacOSOffice SuiteWindows

The rule states no platform. This is derived from the 2 ATT&CK techniques it maps to.

Log source category
event_index

Known benign triggers

  • Legitimate AF_ALG usage from unprivileged users is uncommon, but some kernel crypto tests, IPsec helpers, disk encryption tooling, HSM integrations, or approved security research systems may exercise this interface. Verify the process, user, and host role before adding an exception.

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