Tokenizer: Kernel Mode Driver for Elevating Process Privileges

Tokenizer

Tokenizer is a kernel mode driver project that allows the replacement of a process token in EPROCESS with a system token, effectively elevating the privileges of the process. The driver is designed to be used with a user-mode application that sends a process ID to the driver through an IOCTL.

Technical details

• When a process is created, it inherits the token of the user who created it, The token is used by the system to determine what actions the process can perform. The token contains information about the user’s security identifier (SID), group memberships, and privileges.

  

• The Token member resides at offset 0x4b8 in the _EPROCESS structure, which is a data structure that represents a process object. The Token member is defined in _EX_FAST_REF structure, which is a union type that can store either a pointer to a kernel object or a reference count, depending on the size of the pointer, The offset of the _EX_FAST_REF structure within _EPROCESS depends on the specific version of Windows being used, but it is typically located at an offset of 0x4b8 in recent versions of Windows.

• Windows Build Number token Offsets for x64 and x86 Architectures

  x64 offsets	x86 offsets
  0x0160 (late 5.2)	0x0150 (3.10)
  0x0168 (6.0)	0x0108 (3.50 to 4.0)
  0x0208 (6.1)	0x012C (5.0)
  0x0348 (6.2 to 6.3)	0xC8 (5.1 to early 5.2)
  0x0358 (10.0 to 1809)	0xD8 (late 5.2)
  0x0360 (1903)	0xE0 (6.0)
  0x04B8	0xF8 (6.1)
  	0xEC (6.2 to 6.3)
  	0xF4 (10.0 to 1607)
  	0xFC (1703 to 1903)
  	0x012C

  

• The _EX_FAST_REF structure in Windows contains three members: Object and RefCount and Value

  

• To display the process token in _EX_FAST_REF,We pass the address of the _EX_FAST_REF structure that contains the token, which is typically located at an offset of 0x4b8 in the _EPROCESS structure.”

  

Usage

• You can either spawn a privileged process or elevate an already existing process ID.

  

• For the sake of this explanation, we will focus on the second option and use CMD as an example

  

• inherited Token

  

• send the Process ID to the driver through an IOCTL

  

• After receiving the PID from the user mode application, the driver uses it to obtain a pointer to the _EPROCESS structure for the target process. The driver then accesses the Token member of the _EPROCESS structure to obtain a pointer to the process token, which it replaces with the system token, effectively changing the security context of the process to that of the system. However, if the driver does not correctly locate the Token member within the _EPROCESS structure or if the offset of the Token is other than 0x4b8 , the driver may crash the system or the target process ,this problem will be fixed in the next updates .

  

• cmd token after

  

• the process privileges, groups, rights

  

Download