CVE-2017-10790

What it actually does

The _asn1_check_identifier function in GNU Libtasn1 performs a NULL pointer dereference when processing crafted ASN.1 input that forces assignment of a NULL value to an asn1_node structure, resulting in an immediate process crash.

Why it matters to the business

Applications relying on this library for ASN.1 or certificate handling can be forced offline, causing service outages and requiring restarts; the age of the flaw and available exploit code increase urgency for any remaining deployments.

How an attack unfolds

An attacker crafts malicious ASN.1 data and supplies it to a network-facing service that uses vulnerable libtasn1 for parsing; the library's _asn1_check_identifier routine dereferences a NULL pointer and crashes the process, achieving denial of service.

How to fix it

Upgrade GNU Libtasn1 to a version newer than 4.12; rebuild and redeploy all dependent applications; monitor vendor advisories for any downstream packages that embed the library.

How to confirm the fix worked

Confirm installed version exceeds 4.12; run regression tests with known trigger inputs to verify absence of crash; scan build artifacts for static linkage of older libtasn1 binaries.

Typical attack path

1. Identify a target application or service that links against GNU Libtasn1 <= 4.12 and accepts ASN.1 input over the network
2. Generate ASN.1 data that triggers NULL assignment inside an asn1_node structure
3. Send the crafted payload to the target parser
4. Observe process crash and service interruption

How to detect it

Search application and system logs for abrupt crashes or segmentation faults in processes linked to libtasn1; monitor for sudden restarts of services that parse ASN.1 data; review core dumps or stack traces containing _asn1_check_identifier.

What your security team should do

• Inventory all systems and containers that ship or link libtasn1 and prioritize upgrades
• Apply patches or rebuilds immediately given public exploit availability
• Add libtasn1 version checks to CI/CD pipelines and container scanning
• Review network-exposed services that parse ASN.1 or certificates for exposure