Detect Exploitation for Privilege Escalation in CrowdStrike LogScale
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/
LogScale Detection Query
// T1068 BYOVD — Known Vulnerable Driver Load and Suspicious Staging Path
#event_simpleName = DriverLoad
| lowerDriver := lower(ImageFileName)
| regex("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",
field=lowerDriver, as=IsKnownVulnDriver)
| regex("\\\\(?:temp|tmp|downloads|appdata|users\\\\public|programdata|perflogs|\\$recycle\.bin|windows\\\\tasks)\\\\",
field=lowerDriver, as=IsSuspiciousPath)
| IsKnownVulnDriver = true OR IsSuspiciousPath = true
| DetectionSignal := if(IsKnownVulnDriver = true,
"KnownVulnerableDriverLoaded",
"DriverFromSuspiciousPath")
| table(
[timestamp, ComputerName, UserName, DetectionSignal,
ImageFileName, SHA256HashData, IsKnownVulnDriver, IsSuspiciousPath])
| sort(timestamp, order=desc)CrowdStrike LogScale (CQL) detection for BYOVD kernel driver loading using Falcon sensor's native DriverLoad telemetry (T1068). Uses regex() with as= parameter to create scored boolean fields without filtering, then applies a combined filter for analyst-facing triage. Falcon's DriverLoad event provides richer context than Sysmon Event 6 — including SHA256HashData for immediate IOC correlation and rapid prevention policy creation. The ImageFileName field contains the full driver path. Covers known-vulnerable drivers used by Embargo (MS4Killer), ZeroCleare (VBoxDrv.sys), APT29 (CVE-2021-36934 toolchain), and Turla (VBoxDrv.sys exploitation variants).
Data Sources
Required Tables
False Positives & Tuning
- MSI Afterburner and EVGA Precision X1 loading RTCore64.sys or RTCore32.sys for GPU overclocking MMIO register access — highest-volume false positive class; allowlist in Falcon policy by Authenticode certificate (Micro-Star International) rather than by name to avoid hash-chasing after vendor updates
- Oracle VirtualBox loading VBoxDrv.sys — allowlist by Oracle's Authenticode signing certificate in Falcon's driver policy rather than by path, since the driver may appear in %TEMP% during upgrade workflows
- ASUS ROG Armoury Crate loading AsrDrv10x.sys or GDrv.sys on gaming workstations — in enterprise environments this software is rarely business-justified and should still trigger investigation even if suppressed for specific verified hashes
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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