In Red Teaming planning, BYOVD (Bring Your Own Vulnerable Driver) acts as a magnifying glass to understand the extent of defenses when an external, signed but vulnerable driver could infiltrate. This article, using an authoritative and educational framework, reveals the implications for detection, response, and operational hardening. Join us for practical insights that turn simulation into a more proactive and informed defense.
Life cycle of a Read Timing exercise
In the planning process of a Red Teaming exercise, the phases of the exercise's life cycle are specified, with the aim of establishing a common guide for all stakeholders:
From external reconnaissance and initial access to the victim, to the information exfiltration phases and impact on operational capabilities, both cybercriminals and ethical hackers employ various defense evasion techniques. These techniques allow them to remain stealthy against solutions such as EDR, SIEM, and firewalls. One of these widely used techniques is known as "Bring Your Own Vulnerable Driver" (BYOVD).
“Bring Your Own Vulnerable Driver” (BYOVD)
This technique is widely used by threat groups, as well as offensive security professionals, to remain undetected and carry out actions that would have previously been blocked.
To gain access to a system, cybercriminals and threat actors exploit vulnerabilities already present in the target's software. The BYOVD technique follows a different philosophy: if a signed, trusted, but vulnerable external component is injected into the operating system, it can be exploited to carry out operations for which permissions were not previously granted.
In this way, software with vulnerabilities (recognized or zero-day) is incorporated to be subsequently exploited.
Our security team has detected vulnerabilities that allow the execution of a BYOVD attack.
What are we up against?
This software operates with privileges even higher than those of an administrator, so malware specifically designed to exploit these vulnerabilities can perform actions such as:
Disable EDR and SIEM
Disable native operating system protections
Block communication between the computer and a cloud security management console
Exfiltrate information without leaving a trace
Deploy ransomware without obstacles
Security solution providers, such as Sophos, Crowdstrike, and Microsoft, regularly update their block lists of vulnerable components to detect when one of these pieces of software is incorporated into the system, thereby preventing most attacks of this nature.
Beyond trust...
BYOVD demonstrates that driver signing doesn't guarantee security; component integrity and behavior must be monitored beyond the signature. A layered defense involves managing driver loading, enforcing signature policies, hardening modules, and detecting anomalous signatures or behavior. Vulnerability and supply chain management, along with least privilege and continuous monitoring, strengthen the security posture.
Authorized Red Teaming should result in practical improvements in incident detection and response, as well as updated procedures.
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