Detect Firmware Corruption in CrowdStrike LogScale
Adversaries may overwrite or corrupt the flash memory contents of system BIOS or other firmware in devices attached to a system in order to render them inoperable or unable to boot, thus denying the availability to use the devices and/or the system. Firmware is software that is loaded and executed from non-volatile memory on hardware devices in order to initialize and manage device functionality. These devices may include the motherboard, hard drive, or video cards. Real-world examples include TrickBot's 'Trickboot' module (2020), which can write or erase UEFI/BIOS firmware of a compromised device, and Bad Rabbit ransomware, which installed a modified bootloader to prevent normal boot-up. Firmware corruption often results in permanent hardware denial-of-availability and may be combined with data destruction for maximum impact.
MITRE ATT&CK
- Tactic
- Impact
- Technique
- T1495 Firmware Corruption
- Canonical reference
- https://attack.mitre.org/techniques/T1495/
LogScale Detection Query
// T1495 - Firmware Corruption Detection
// Signal 1: Known firmware tool execution
#event_simpleName = ProcessRollup2
| FileName = /(?i)(rw\.exe|rw64\.exe|rweverything\.exe|chipsec\.exe|chipsec_main\.exe|flashrom\.exe|fpt\.exe|fptw\.exe|fptw64\.exe|afuwin\.exe|afuwin64\.exe|afudos\.exe|meinfo\.exe|meinfowin\.exe|meinfowin64\.exe|amidewin\.exe|amidewin64\.exe|h2offt\.exe|h2offt-w\.exe|winphlash\.exe|winphlash64\.exe|ubuild\.exe|ubu\.exe)$/
| eval Signal = "KnownFirmwareTool"
| eval RiskScore = 3
// Signal 2: Firmware write/erase command-line patterns
| union [
#event_simpleName = ProcessRollup2
| CommandLine = /(?i)(--write|--erase|--flash|spi[._]write|bios[. ]write|uefi[. ]write|flash[. ]write|nvram[. ]write|WRITESPI|\/WRITESPI|flashrom\s+-w|chipsec_util.spi.write)/
| eval Signal = "FirmwareWriteOperation"
| eval RiskScore = 3
]
// Signal 3: PowerShell UEFI or BCD tampering
| union [
#event_simpleName = ProcessRollup2
| FileName = /(?i)(powershell|pwsh)\.exe$/
| CommandLine = /(?i)(Set-SecureBootUEFI|Set-UEFIVariable|bcdedit.*\/set|bcdedit.*\/delete|bcdedit.*\/deletevalue)/
| eval Signal = "UEFIOrBCDTamper"
| eval RiskScore = 4
]
// Signal 4: Suspicious firmware kernel driver load
| union [
#event_simpleName = DriverLoad
| ImageFileName = /(?i)(rw\.sys|rwdrv\.sys|winio\.sys|winio32\.sys|winio64\.sys|physmem\.sys|pmem\.sys|dbutil_2_3\.sys|rtcore64\.sys)$/
| eval Signal = "SuspiciousFirmwareDriver"
| eval RiskScore = 5
]
| groupBy([ComputerName, UserName, FileName, CommandLine, ParentBaseFileName, Signal], function=[
max(RiskScore, as=MaxRiskScore),
count(as=EventCount),
min(timestamp, as=FirstSeen),
max(timestamp, as=LastSeen)
])
| eval SuspiciousParent = if(ParentBaseFileName = /(?i)(cmd\.exe|powershell\.exe|pwsh\.exe|wscript\.exe|cscript\.exe|mshta\.exe|explorer\.exe)/, "true", "false")
| sort(MaxRiskScore, order=desc)
| select([LastSeen, ComputerName, UserName, FileName, CommandLine, ParentBaseFileName, Signal, MaxRiskScore, EventCount, SuspiciousParent])CrowdStrike LogScale (Falcon) CQL query detecting T1495 Firmware Corruption via four correlated signals: known firmware tool execution (RWEverything, Chipsec, flashrom, AFU tools), write/erase/flash command-line patterns, PowerShell-based UEFI variable or BCD modification, and suspicious firmware kernel driver loads (winio, physmem, dbutil). Results are grouped by host/user/process and sorted by risk score. Driver loads receive the highest risk weight (5) as they indicate BYOVD-style hardware access.
Data Sources
Required Tables
False Positives & Tuning
- CrowdStrike Falcon sensor updates or third-party EDR products that load kernel drivers (physmem.sys, pmem.sys) for legitimate memory access or hardware enumeration during initialization
- IT asset management or hardware inventory tools that invoke RWEverything or fpt.exe in read-only mode for BIOS version discovery during automated hardware audits
- Vendor-certified BIOS update workflows triggered via SCCM or Intune that spawn h2offt.exe or afuwin64.exe with flash write arguments from trusted parent processes under approved service accounts
Other platforms for T1495
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 1CHIPSEC UEFI Variable Enumeration — Read-Only Firmware Reconnaissance
Expected signal: Sysmon Event ID 1: Process Create with Image=python.exe, CommandLine containing 'chipsec_util.py uefi var-list'. Sysmon Event ID 6: Driver load for chipsec.sys (or chipsec_hlpr.sys) from a temp or install directory. Security Event ID 7045: New service installed for the CHIPSEC kernel driver. Windows may prompt for UAC on driver installation.
- Test 2RW-Everything Hardware Access Tool Execution with Ring-0 Driver Load
Expected signal: Sysmon Event ID 1: Process Create with Image=Rw.exe and CommandLine containing '/Command="PCI 0 0 0 0 10"'. Sysmon Event ID 6: Driver load for rw.sys from tool directory or System32\drivers\. Security Event ID 7045: New service named 'RW' registered pointing to rw.sys. Service exits after tool completes but driver load telemetry persists.
- Test 3PowerShell BCD Store Modification — Bad Rabbit Bootloader Tamper Simulation
Expected signal: Sysmon Event ID 1: Process Create for powershell.exe with CommandLine containing 'bcdedit /set' and ExecutionPolicy Bypass. Two additional Sysmon EventCode=1 events for bcdedit.exe child processes. Security Event ID 4688 (if command-line auditing enabled) for both bcdedit invocations. PowerShell ScriptBlock Log Event ID 4104 capturing the full command.
- Test 4Linux flashrom SPI Flash Probe — Non-Destructive Hardware Reconnaissance
Expected signal: Linux auditd EXECVE record with a=flashrom, argv containing '-p', 'internal', '--no-action', '-V'. Syslog entry capturing sudo invocation and flashrom execution. On systems with Sysmon for Linux (EventID 1): Process Create event for flashrom. /var/log/auth.log entry recording sudo authentication for the flashrom command.
- Test 5Intel Flash Programming Tool (FPT) Flash Descriptor Read
Expected signal: Sysmon Event ID 1: Process Create with Image=fptw64.exe, CommandLine containing '-DESC -d'. Sysmon Event ID 11: File Create event for df00tech_flashdesc.bin in %TEMP%. Security Event ID 7045 may appear if FPT installs a kernel service for hardware access. The .bin file size will reflect the flash descriptor region size (typically 4KB).
References (8)
- https://attack.mitre.org/techniques/T1495/
- https://securelist.com/bad-rabbit-ransomware/82851/
- https://eclypsium.com/research/trickbot-now-offers-trickboot-persist-brick-profit/
- https://www.cisa.gov/uscert/ncas/alerts/aa22-057a
- https://cyber.dhs.gov/assets/report/ar-16-20173.pdf
- https://chipsec.github.io/
- https://www.flashrom.org/
- https://web.archive.org/web/20190508170055/https://www.symantec.com/security-center/writeup/2000-122010-2655-99
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