Detect Exploitation for Privilege Escalation in Google Chronicle
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges. Exploitation of a software vulnerability occurs when an adversary takes advantage of a programming error in a program, service, or within the operating system software or kernel itself to execute adversary-controlled code. Security constructs such as permission levels will often hinder access to information and use of certain techniques, so adversaries will likely need to perform privilege escalation to include use of software exploitation to circumvent those restrictions. When initially gaining access to a system, an adversary may be operating within a lower privileged process which will prevent them from accessing certain resources on the system. Vulnerabilities may exist, usually in operating system components and software commonly running at higher permissions, that can be exploited to gain higher levels of access on the system. A key sub-technique is Bring Your Own Vulnerable Driver (BYOVD), where adversaries drop a legitimately signed but vulnerable kernel driver onto a compromised machine and then exploit it to execute code in kernel mode, bypassing Driver Signature Enforcement. Real-world examples include Embargo ransomware using MS4Killer, ZeroCleare using VBoxDrv.sys, APT29 exploiting CVE-2021-36934, and Turla exploiting VBoxDrv.sys vulnerabilities.
MITRE ATT&CK
- Tactic
- Privilege Escalation
- Canonical reference
- https://attack.mitre.org/techniques/T1068/
YARA-L Detection Query
rule T1068_BYOVD_KernelDriverPrivEsc {
meta:
author = "Argus Detection Engineering"
description = "Detects BYOVD (Bring Your Own Vulnerable Driver) technique and exploitation for privilege escalation (T1068). Monitors DRIVER_LOAD events for known-vulnerable driver names from the public LOLDRIVERS blocklist and for .sys files staged in suspicious user-writable paths used to bypass Driver Signature Enforcement."
severity = "CRITICAL"
priority = "HIGH"
mitre_attack_tactic = "Privilege Escalation"
mitre_attack_technique = "T1068"
reference = "https://attack.mitre.org/techniques/T1068/"
version = "1.0"
events:
$e.metadata.event_type = "DRIVER_LOAD"
$e.principal.hostname = $hostname
(
// Signal 1: Known vulnerable driver name (BYOVD blocklist)
re.regex($e.target.file.full_path,
`(?i)(rtcore64\.sys|rtcore32\.sys|gdrv2?\.sys|asrdrv10[012]?\.sys|aswarpot\.sys|vboxdrv\.sys|dbutil_2_3\.sys|dbutildrv2\.sys|mhyprot[23]?\.sys|iqvw(?:64|32)e\.sys|winring0(?:x64)?\.sys|capcom\.sys|msio(?:64|32)\.sys|ms4killer\.sys|glckio2\.sys|physmem\.sys|nvflash\.sys|nicm\.sys|nscm\.sys|spwizeng\.sys|bs_rcio64\.sys)`)
or
// Signal 2: Driver loaded from suspicious user-writable staging path
re.regex($e.target.file.full_path,
`(?i)\\(?:temp|tmp|downloads|appdata\\(?:local|roaming)|users\\public|programdata|\$recycle\.bin|windows\\tasks|perflogs)\\`)
)
condition:
$e
}Chronicle YARA-L 2.0 rule detecting BYOVD kernel driver privilege escalation (T1068). Operates on UDM DRIVER_LOAD events populated from Sysmon Event 6 ingested via Chronicle's Windows Sysmon log parser. Uses re.regex() against target.file.full_path to evaluate both known-vulnerable driver names (covering Embargo, BlackByte, APT29, ZeroCleare, and Turla toolsets) and suspicious user-writable staging paths. The single-event condition alerts immediately with no sequence dependency, maximising detection speed for this high-severity technique.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate hardware vendor utilities (ASUS Armoury Crate, Gigabyte App Center, MSI Dragon Center) loading GDrv.sys, AsrDrv10x.sys, or RTCore64.sys from standard %ProgramData% installation paths for fan, LED, and voltage hardware access
- Gaming anti-cheat kernel drivers (Vanguard, EasyAntiCheat, BattlEye kernel module) where some vendors historically reused driver names present in BYOVD blocklists — verify Authenticode certificate against the allowlist before suppressing
- Oracle VirtualBox loading VBoxDrv.sys from %TEMP% staging path during installer execution on developer workstations before final placement in C:\Program Files\Oracle\VirtualBox
Other platforms for T1068
Testing Methodology
Validate this detection against 5 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1BYOVD — Drop and Register Known Vulnerable Driver (RTCore64.sys Simulation)
Expected signal: Windows Security Event ID 4697 (New Service Installed): ServiceName=RTCore64, ServiceFileName=C:\Windows\Temp\RTCore64.sys, ServiceType=0x1 (Kernel Driver). Sysmon Event ID 1 (Process Create): Image=sc.exe, CommandLine containing 'create RTCore64 type= kernel'. DeviceRegistryEvents: RegistryKey containing \Services\RTCore64, RegistryValueName=ImagePath, RegistryValueData=C:\Windows\Temp\RTCore64.sys.
- Test 2Suspicious Driver Load Path — Copy System Driver to Temp and Reload
Expected signal: Sysmon Event ID 11 (File Create): TargetFilename=C:\Users\Public\null_test.sys. Security Event ID 4697: ServiceFileName=C:\Users\Public\null_test.sys, ServiceType=0x1. DeviceRegistryEvents: RegistryKey containing \Services\TestPathDriver, ImagePath=C:\Users\Public\null_test.sys.
- Test 3SeLoadDriverPrivilege Assignment via sc.exe (Privilege Telemetry)
Expected signal: Security Event ID 4697: ServiceName=FakePrivTest, ServiceType=0x1. Security Event ID 4672: PrivilegeList containing SeLoadDriverPrivilege assigned to the calling session's SubjectLogonId. System Event ID 7045 (New Service Installed) in System event log. sc.exe Process Create in Sysmon Event ID 1.
- Test 4Linux Kernel Module Load from Non-Standard Path (Container/Linux)
Expected signal: Auditd SYSCALL record with syscall=finit_module or init_module, uid/euid of calling process. Syslog/kern.log message: 'df00tech_test: disagrees about version of symbol module_layout' or 'insmod: ERROR: could not insert module'. Auditd WATCH record for file access to /tmp/df00tech_test.ko. /var/log/audit/audit.log entries with key=t1068_test.
- Test 5BYOVD — Enumerate Loaded Drivers for Vulnerable Candidates
Expected signal: Sysmon Event ID 1 (Process Create): driverquery.exe, sc.exe, powershell.exe executions with respective command lines. Security Event ID 4688 (if command-line auditing enabled) for same processes. WMI Activity log entries for Win32_SystemDriver query in Microsoft-Windows-WMI-Activity/Operational.
References (12)
- https://attack.mitre.org/techniques/T1068/
- https://www.loldrivers.io/
- https://learn.microsoft.com/en-us/windows/security/threat-protection/windows-defender-application-control/microsoft-recommended-driver-block-rules
- https://www.welivesecurity.com/wp-content/uploads/2020/06/ESET_InvisiMole.pdf
- https://unit42.paloaltonetworks.com/acidbox-rare-malware/
- https://www.welivesecurity.com/en/eset-research/embargo-ransomware-rockyou2024-data-leak-ms4killer/
- https://github.com/wavestone-cdt/EDRSandblast
- https://github.com/Idov31/Nidhogg
- https://learn.microsoft.com/en-us/sysinternals/downloads/sysmon
- https://learn.microsoft.com/en-us/defender-endpoint/advanced-hunting-deviceimageloadevents-table
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1068/T1068.md
- https://github.com/SigmaHQ/sigma/tree/master/rules/windows/driver_load
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