Function at 0x420820
Capabilities:
Allocate or change rwx memory
Execute shellcode via indirect call
Hook routines via microsoft detours

Disassembly:
sub esp, 0x40
push ebx
push ebp
push esi
mov esi, eax
cmp esi, 0x7ff80000
push edi
jbe 0x42083d
lea ebx, [esi - 0x7ff80000]
mov dword [esp + 0x14], ebx
jmp 0x420849
mov dword [esp + 0x14], 0x10000
mov ebx, dword [esp + 0x14]
cmp esi, 0x80000000
jae 0x42085d
lea edi, [esi + 0x7ff80000]
mov dword [esp + 0x10], edi
jmp 0x420869
mov dword [esp + 0x10], 0xfff80000
mov edi, dword [esp + 0x10]
mov eax, dword [0x43d534]
test eax, eax
mov edx, dword [0x43d530]
jne 0x420883
test edx, edx
je 0x420896
mov eax, edx
mov dword [0x43d534], eax
mov ecx, dword [eax + 8]
test ecx, ecx
je 0x420896
cmp ecx, ebx
jb 0x420896
cmp ecx, edi
jbe 0x420a0f
test edx, edx
mov eax, edx
mov dword [0x43d534], eax
je 0x4208c4
test eax, eax
je 0x4208b8
mov ecx, dword [eax + 8]
test ecx, ecx
je 0x4208b8
cmp ecx, ebx
jb 0x4208b8
cmp ecx, edi
jbe 0x420a0a
mov eax, dword [eax + 4]
test eax, eax
jne 0x4208a5
mov dword [0x43d534], eax
mov ebp, dword [sym.imp.KERNEL32.dll_VirtualQuery]
mov eax, esi
and eax, 0xffff
sub esi, eax
cmp esi, ebx
mov ebx, dword [sym.imp.KERNEL32.dll_VirtualAlloc]
mov edi, esi
jbe 0x42093c
nop
lea ecx, [edi - 0x70000000]
cmp ecx, 0x10000000
ja 0x4208f3
mov edi, 0x6fff0000
push 0x1c
lea edx, [esp + 0x38]
push edx
push edi
call ebp
test eax, eax
je 0x42093c
mov eax, 0x10000
cmp dword [esp + 0x44], eax
jne 0x420912
cmp dword [esp + 0x40], eax
jae 0x420924
mov edi, dword [esp + 0x38]
add edi, 0xffff0000
cmp edi, dword [esp + 0x14]
ja 0x4208e0
jmp 0x42093c
push 0x40
push 0x3000
push eax
push edi
call ebx
test eax, eax
mov dword [0x43d534], eax
jne 0x4209c7
mov edi, dword [esp + 0x10]
cmp esi, edi
jae 0x4209bd
jmp 0x420950
lea eax, [esi - 0x70000000]
cmp eax, 0x10000000
ja 0x420962
mov esi, 0x80010000
push 0x1c
lea ecx, [esp + 0x1c]
push ecx
push esi
call ebp
test eax, eax
je 0x4209bd
mov edx, 0x10000
cmp dword [esp + 0x28], edx
jne 0x4209ae
cmp dword [esp + 0x24], edx
jb 0x4209ae
movzx ecx, si
test ecx, ecx
je 0x42099a
mov esi, dword [esp + 0x18]
mov eax, edx
sub eax, ecx
sub dword [esp + 0x24], eax
add esi, eax
mov dword [esp + 0x18], esi
push 0x40
push 0x3000
push edx
push esi
call ebx
test eax, eax
mov dword [0x43d534], eax
jne 0x4209c7
mov edx, dword [esp + 0x18]
mov eax, dword [esp + 0x24]
lea esi, [edx + eax]
cmp esi, edi
jb 0x420950
pop edi
pop esi
pop ebp
xor eax, eax
pop ebx
add esp, 0x40
ret
mov ecx, dword [0x43d530]
xor edx, edx
mov dword [eax + 4], ecx
mov dword [eax], 0x52727464
mov dword [eax + 8], edx
mov dword [0x43d530], eax
lea ecx, [eax + 0xffe0]
mov esi, 0x7fd
jmp 0x4209f0
mov dword [ecx + 0x18], edx
mov edx, ecx
sub ecx, 0x20
sub esi, 1
jne 0x4209f0
mov edi, dword [esp + 0x10]
mov ebx, dword [esp + 0x14]
mov dword [eax + 8], edx
jmp 0x420a0f
mov dword [0x43d534], eax
mov ecx, dword [eax + 8]
cmp ecx, ebx
jb 0x4209bd
cmp ecx, edi
ja 0x4209bd
mov edx, dword [ecx + 0x18]
mov dword [eax + 8], edx
mov eax, 0xcccccccc
mov dword [ecx], eax
mov dword [ecx + 4], eax
mov dword [ecx + 8], eax
mov dword [ecx + 0xc], eax
pop edi
mov dword [ecx + 0x10], eax
mov dword [ecx + 0x14], eax
pop esi
mov dword [ecx + 0x18], eax
pop ebp
mov dword [ecx + 0x1c], eax
mov eax, ecx
pop ebx
add esp, 0x40
ret