CVE-2015-7613

What it actually does

Race condition during IPC object creation allows uid/gid comparisons against uninitialized kernel memory, enabling local privilege escalation to root.

Why it matters to the business

Attackers with local access on unpatched Linux systems can obtain full administrative control, leading to data theft, persistence, or ransomware deployment on affected servers and endpoints; the vulnerability has been public for over a decade with working exploits available.

How an attack unfolds

An attacker with local shell access triggers concurrent IPC operations that race against ipc_addid, causing the kernel to use uninitialized uid/gid values and grant elevated privileges to attacker-controlled objects.

How to fix it

Upgrade the Linux kernel to a version newer than 4.2.3 that contains the fix for the uninitialized data checks in msg.c, shm.c, and util.c; apply vendor backports if running older long-term kernels; reboot after installation.

How to confirm the fix worked

Verify kernel version is newer than 4.2.3 and that the relevant patches for ipc_addid initialization are present via source inspection or distro advisory; run existing public test cases that previously triggered the race to confirm absence of the flaw.

Typical attack path

1. Obtain local user shell on target Linux system
2. Compile and execute exploit that races ipc_addid calls in msg/shm paths
3. Trigger kernel path that performs uid/gid checks against uninitialized data
4. Receive elevated credentials and spawn root shell or install payload

How to detect it

Review kernel logs and audit records for unusual IPC object creation patterns or privilege changes around the time of suspected local access; correlate with process execution of untrusted binaries that perform heavy msgget/shmget activity.

What your security team should do

• Immediately inventory all Linux systems and identify those running kernel 4.2.3 or older
• Prioritize patching internet-facing or high-value systems first given public exploit availability
• Enable kernel hardening features such as grsecurity or SELinux to reduce local exploitation surface
• Monitor for new local privilege-escalation attempts until all systems are updated