John Klimarchuk

PSIRT Incident Manager

Security Research and Operations

John Klimarchuk, CISSP 20512 works as a PSIRT Incident Manager in the Security Research and Operations organization at Cisco. In this role, John investigates, drives to resolution and writes associated security advisories for any reported vulnerability affecting Cisco products.

John has over 15 years of experience working with information technology and cyber security. John has designed, implemented, and supported numerous secure networks from Fortune 500 to startup companies.

Prior to his current role, he supported several product’s in Cisco's Technical Assistance Center (TAC).


June 14, 2016


Advanced Malware Evasion Techniques HTTP-Evader

1 min read

Malware doesn’t play by the rules, so today’s IT infrastructure needs to provide several layers of defense for end-users.  Some of the more common devices used to protect modern networks are Intrusion Prevention systems (IPS) and Firewalls. In recent years, there has been a lot of research on how evasion techniques bypass Intrusion Prevention systems […]

January 29, 2016


Linux Kernel Zero-Day Privilege Escalation Vulnerability CVE-2016-0728

1 min read

On January 20, 2016, a new Linux Kernel zero-day vulnerability (CVE-2016-0728) was disclosed by Perception Point. The vulnerability has the potential to allow attackers to gain root on affected devices by running a malicious Android or Linux application. Our investigation is ongoing; however, at this time we have not identified any Cisco products as exploitable. […]