Theodosius - Jit linker, Mapper, Mutator, and Obfuscator

Theodosius (Theo for short) is a jit linker created entirely for obfuscation and mutation of both code, and code flow. The project is extremely modular in design and supports both kernel and usermode projects. Since Theo inherits HMDM (highly modular driver mapper), any vulnerable driver that exposes arbitrary MSR writes, or physical memory read/write can be used with this framework to map unsigned code into the kernel. This is possible since HMDM inherits VDM (vulnerable driver manipulation), and MSREXEC (elevation of arbitrary MSR writes to kernel execution).

Since Theo is a jit linker, unexported symbols can be jit linked. Resolving such symbols is open ended and allows the programmer of this framework to handle how they want to resolve symbols. More on this later (check out example projects).

Obfuscation

The usage of the word obfuscation in this project is use to define any changes made to code, this includes code flow. obfuscation::obfuscate, a base class, which is inherited and expanded upon by obfuscation::mutation, obfuscates code flow by inserting JMP [RIP+0x0] instructions after every single instruction. This allows for a routine to be broken up into unique allocations of memory and thus provides more canvas room for creative ideas.

Obfuscation - Base Class

The base class, as described in the above section, contains a handful of util routines and a single explicit constructor which is the corner stone of the class. The constructor fixes JCC relative virtual addresses so that if the condition is met, instead of jumping instruction pointer relativitly, it will jump to an addition jmp (JMP [RIP+0x0]). LEA, nor CALL are rip relative, even for symbols defined inside of the routine in which the instruction is compiled into. In other words JCC instructions are the only instruction pointer relative instructions that are generated.

reloc_t inline_jmp_reloc
{
	reloc_type::next_instruction_addr,
	JMP_RIP_ADDR_IDX
};

reloc_t inline_jmp_branch
{
	reloc_type::jcc,
	JMP_RIP_ADDR_IDX,
	*reinterpret_cast<std::int32_t*>(rva_fix_addr)
};

std::printf("			> fixing JCC rva...\n");
std::printf("				> new rva = 0x%x\n", JMP_RIP_SIZE);
std::printf("				> old rva = 0x%x\n",
	*reinterpret_cast<std::int32_t*>(rva_fix_addr));

// when you inherit obfuscate please be mindful of JCC rvas...
*reinterpret_cast<std::int32_t*>(rva_fix_addr) = JMP_RIP_SIZE;

gadget_stack.push_back({ instruction.second, {} });
gadget_stack.push_back({ jmp_rip, inline_jmp_reloc });
gadget_stack.push_back({ jmp_rip, inline_jmp_branch });

Mutation - Inherts Obfuscation