CVE-2016-0758

What it actually does

Integer overflow in the ASN.1 decoder allows out-of-bounds memory access and corruption when processing crafted data, enabling local privilege escalation to root.

Why it matters to the business

Attackers with local access can fully compromise affected Linux systems, leading to data theft, persistence, or lateral movement; urgency is low given the 2016 disclosure and widespread patching but still relevant for legacy deployments.

How an attack unfolds

An attacker with local access supplies specially crafted ASN.1 data to a kernel component using the vulnerable decoder; the integer overflow triggers memory corruption that is leveraged to overwrite function pointers or gain arbitrary code execution with elevated privileges.

How to fix it

Upgrade the Linux kernel to a version containing commit 23c8a812dc3c621009e4f0e5342aa4e2ede1ceaa or any later release that resolves the integer overflow in lib/asn1_decoder.c.

How to confirm the fix worked

Verify the running kernel version is at or beyond the fixed commit; inspect kernel source or binary for the patched asn1_decoder logic and confirm absence of the overflow condition via code review or regression tests.

Typical attack path

1. Obtain local shell on target system
2. Identify vulnerable kernel build via uname or /proc/version
3. Prepare and deliver crafted ASN.1 payload to trigger decoder path
4. Exploit resulting memory corruption for privilege escalation
5. Establish persistence or perform post-exploitation actions

How to detect it

Examine kernel logs for oops or panic entries referencing asn1_decoder.c; monitor for unexpected setuid binaries, sudden privilege changes, or processes executing with elevated credentials following ASN.1-related activity.

• asn1_decoder.c
• integer overflow
• kernel oops asn1

What your security team should do

• Prioritize kernel updates on all exposed systems
• Limit local user privileges and enforce least-privilege access
• Enable kernel hardening features such as SMEP/SMAP where available
• Review legacy or embedded devices still running pre-4.6 kernels