Personal commit

shellcode-util/src/lib.rs

@@ -0,0 +1,128 @@
+#![no_std]
+#![feature(core_intrinsics)]
+#![allow(internal_features)]
+#![allow(unused_imports)]
+
+use core::{arch::asm, ffi::CStr, intrinsics, slice};
+use windows_sys::{
+    core::PCSTR,
+    Win32::{
+        Foundation::{HMODULE, UNICODE_STRING},
+        System::{
+            Diagnostics::Debug::{
+                IMAGE_DIRECTORY_ENTRY_EXPORT, IMAGE_NT_HEADERS32, IMAGE_NT_HEADERS64,
+            },
+            SystemServices::{IMAGE_DOS_HEADER, IMAGE_EXPORT_DIRECTORY},
+            Threading::TEB,
+            WindowsProgramming::LDR_DATA_TABLE_ENTRY,
+        },
+    },
+};
+
+pub unsafe fn get_module_handle_from_peb(module_name: &[u16]) -> Option<HMODULE> {
+    // Start at the top boys
+    let mut teb: *mut TEB;
+    #[cfg(target_arch = "x86")]
+    asm!(
+        "mov {}, fs:[0x18]",
+        out(reg) teb
+    );
+    #[cfg(target_arch = "x86_64")]
+    asm!(
+        "mov {}, gs:[0x30]",
+        out(reg) teb
+    );
+
+    // I will dereference every pointer
+    let teb = *teb;
+    let peb = *(teb.ProcessEnvironmentBlock);
+    let ldr_data = *(peb.Ldr);
+
+    // Hidden fields of PEB_LDR_DATA and LDR_DATA_TABLE_ENTRY abound
+    // Reserved2[0] = SsHandle, Reserved[1] = InLoadOrderLinks.Flink, Reserved[2] = InLoadOrderLinks.Blink
+    let mut module_list = *(ldr_data.Reserved2[1] as *mut LDR_DATA_TABLE_ENTRY);
+
+    while !module_list.DllBase.is_null() {
+        // BaseDllName
+        let base_dll_name = *(module_list.Reserved4.as_ptr() as *mut UNICODE_STRING);
+        let base_dll_name = slice::from_raw_parts(
+            base_dll_name.Buffer,
+            base_dll_name.Length as usize / size_of::<u16>(),
+        );
+
+        if module_name == base_dll_name {
+            return Some(module_list.DllBase as HMODULE);
+        }
+
+        // Reserved1[0] = InLoadOrderLinks.Flink, Reserved1[1] = InLoadOrderLinks.Blink
+        module_list = *(module_list.Reserved1[0] as *mut LDR_DATA_TABLE_ENTRY);
+    }
+    None
+}
+
+pub unsafe fn get_procedure_from_edt<F>(module: HMODULE, proc_name: &str) -> Option<F> {
+    let module = module as usize;
+    let proc_name = CStr::from_ptr(proc_name.as_ptr() as *const _);
+
+    let dos_headers = *(module as *const IMAGE_DOS_HEADER);
+
+    #[cfg(target_arch = "x86")]
+    let nt_headers = *((module + dos_headers.e_lfanew as usize) as *const IMAGE_NT_HEADERS32);
+    #[cfg(target_arch = "x86_64")]
+    let nt_headers = *((module + dos_headers.e_lfanew as usize) as *const IMAGE_NT_HEADERS64);
+
+    let export_directory = *((module
+        + nt_headers.OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_EXPORT as usize]
+            .VirtualAddress as usize)
+        as *const IMAGE_EXPORT_DIRECTORY);
+
+    let functions_table_ptr =
+        (module + export_directory.AddressOfFunctions as usize) as *const usize;
+    let names_table_ptr = (module + export_directory.AddressOfNames as usize) as *const usize;
+    let ordinals_table_ptr =
+        (module + export_directory.AddressOfNameOrdinals as usize) as *const u16;
+
+    let functions_table = slice::from_raw_parts(
+        functions_table_ptr,
+        export_directory.NumberOfFunctions as usize,
+    );
+    let names_table =
+        slice::from_raw_parts(names_table_ptr, export_directory.NumberOfNames as usize);
+    let ordinals_table =
+        slice::from_raw_parts(ordinals_table_ptr, export_directory.NumberOfNames as usize);
+
+    for i in 0..names_table.len() {
+        let name = CStr::from_ptr((module + names_table[i]) as *const _);
+        let ordinal = ordinals_table[i];
+        let address = functions_table[ordinal as usize];
+
+        if name == proc_name {
+            return Some(intrinsics::transmute_unchecked(module + address));
+        }
+    }
+    None
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use utf16_lit::utf16;
+
+    fn get_module_test() {
+        let module = unsafe { get_module_handle_from_peb(&utf16!("KERNEL32.DLL")) };
+        assert!(!module.is_some());
+    }
+
+    fn get_procedure_test() {
+        let module = unsafe { get_module_handle_from_peb(&utf16!("KERNEL32.DLL")) };
+        assert!(module.is_some());
+
+        let procedure = unsafe {
+            get_procedure_from_edt::<extern "system" fn() -> u32>(module.unwrap(), "GetProcessId\0")
+        };
+        assert!(procedure.is_some());
+
+        let procedure = procedure.unwrap();
+        assert_ne!(procedure(), 0)
+    }
+}