CVE-2017-1000111

What it actually does

Heap out-of-bounds access in AF_PACKET socket handling due to a race between PACKET_RESERVE option updates and safety checks in packet_set_ring, enabling memory corruption.

Why it matters to the business

Local attackers can escalate privileges to root on affected Linux systems, leading to full system compromise, data theft, or persistence in containerized or multi-tenant environments where user namespaces are enabled.

How an attack unfolds

An attacker creates an AF_PACKET socket and uses the PACKET_RESERVE option to trigger a race condition with internal ring buffer checks, corrupting kernel heap memory to execute arbitrary code; user namespaces allow unprivileged processes to obtain the required CAP_NET_RAW capability.

How to fix it

Update the Linux kernel to a patched version that serializes socket state changes with proper locking around PACKET_RESERVE handling; apply vendor-supplied kernel updates for all affected distributions.

How to confirm the fix worked

Verify kernel version is newer than the vulnerable release and test that PACKET_RESERVE updates are now protected by socket locking; confirm no unpatched kernels remain in production via package inventory.

Typical attack path

1. Obtain a process with CAP_NET_RAW via user namespace creation
2. Create an AF_PACKET socket
3. Invoke setsockopt with PACKET_RESERVE while concurrent operations occur on the socket ring
4. Trigger the race to perform out-of-bounds heap access
5. Corrupt kernel structures to achieve privilege escalation or code execution

How to detect it

Review kernel logs and audit records for unusual AF_PACKET socket creation or setsockopt calls involving PACKET_RESERVE from unprivileged contexts; monitor for post-exploitation artifacts such as unexpected privilege changes or kernel oops messages related to packet sockets.

What your security team should do

• Prioritize kernel updates on all systems exposing AF_PACKET sockets or using user namespaces
• Disable unprivileged user namespace creation where not required
• Audit workloads for processes holding CAP_NET_RAW capabilities