in the middle of something, adding branch detection cod

include/vmprofiler.hpp

@@ -172,11 +172,13 @@ namespace vm
     class ctx_t
     {
       public:
-        explicit ctx_t( std::uintptr_t module_base, std::uintptr_t image_base, std::uint32_t vm_entry_rva );
-        ctx_t( std::vector< vm::handler::handler_t > &vm_handlers, zydis_routine_t &vm_entry, zydis_routine_t &calc_jmp,
-               vmp2::exec_type_t exec_type );
+        explicit ctx_t( std::uintptr_t module_base, std::uintptr_t image_base, std::uintptr_t image_size,
+                        std::uintptr_t vm_entry_rva );
+
+        // never change...
+        const std::uintptr_t module_base, image_base, vm_entry_rva, image_size;
+        const vmp2::exec_type_t exec_type;
 
-        vmp2::exec_type_t exec_type;
         zydis_routine_t vm_entry, calc_jmp;
         std::vector< vm::handler::handler_t > vm_handlers;
     };
@@ -213,17 +215,18 @@ namespace vm
             absolute
         };
 
-        struct code_block_t
+        struct jcc_data
         {
-            struct
-            {
-                bool has_jcc;
-                jcc_type type;
-                std::uint32_t block_rva[ 2 ];
-            } jcc;
+            bool has_jcc;
+            jcc_type type;
+            std::uint32_t block_rva[ 2 ];
+        };
 
-            std::uint32_t code_block_rva;
+        struct code_block_t
+        {
+            std::uintptr_t vip_begin;
             std::vector< virt_instr_t > vinstrs;
+            jcc_data jcc;
         };
 
         // decrypt transformations for encrypted virtual instruction rva...
@@ -245,6 +248,39 @@ namespace vm
         /// <param name="vip">virtual instruction pointer, linear virtual address...</param>
         /// <returns>returns immediate value if imm_size is not 0...</returns>
         std::optional< std::uint64_t > get_imm( vm::ctx_t &ctx, std::uint8_t imm_size, std::uintptr_t vip );
+
+        /// <summary>
+        /// get jcc data out of a code block... this function will loop over the code block
+        /// and look for the last two NANDW in the virtual instructions, then it will look
+        /// for the last LCONSTW which is the xor key...
+        ///
+        /// it will then loop and look for all PUSHVSP's, checking each to see if the stack
+        /// contains two encrypted rva's to each branch.. if there is not two encrypted rva's
+        /// then the virtual jmp instruction only has one dest...
+        /// </summary>
+        /// <param name="ctx">vm context</param>
+        /// <param name="code_block">code block that does not have its jcc_data yet</param>
+        /// <returns>if last lconstdw is found, return filled in jcc_data structure...</returns>
+        std::optional< jcc_data > get_jcc_data( vm::ctx_t &ctx, code_block_t &code_block );
+
+        /// <summary>
+        /// the top of the stack will contain the lower 32bits of the RVA to the virtual instructions
+        /// that will be jumping too... the RVA is image based (not module based, but optional header image
+        /// based)... this means the value ontop of the stack could be "40007fd8" with image base being
+        /// 0x140000000... as you can see the 0x100000000 is missing... the below statement deals with this...
+        /// </summary>
+        /// <param name="ctx">vm context</param>
+        /// <param name="entry">current trace entry for virtual JMP instruction</param>
+        /// <returns>returns linear virtual address of the next code block...</returns>
+        std::uintptr_t code_block_addr( const vm::ctx_t &ctx, const vmp2::v2::entry_t &entry );
+
+        /// <summary>
+        /// same routine as above except lower_32bits is passed directly and not extracted from the stack...
+        /// </summary>
+        /// <param name="ctx">vm context</param>
+        /// <param name="lower_32bits">lower 32bits of the relative virtual address...</param>
+        /// <returns>returns full linear virtual address of code block...</returns>
+        std::uintptr_t code_block_addr( const vm::ctx_t &ctx, const std::uint32_t lower_32bits );
     } // namespace instrs
 
     namespace calc_jmp

src/vmctx.cpp

@@ -2,7 +2,9 @@
 
 namespace vm
 {
-    ctx_t::ctx_t( std::uintptr_t module_base, std::uintptr_t image_base, std::uint32_t vm_entry_rva )
+    ctx_t::ctx_t( std::uintptr_t module_base, std::uintptr_t image_base, std::uintptr_t image_size,
+                  std::uintptr_t vm_entry_rva )
+        : module_base( module_base ), image_base( image_base ), image_size( image_size ), vm_entry_rva( vm_entry_rva )
     {
         vm::util::flatten( vm_entry, vm_entry_rva + module_base );
         vm::util::deobfuscate( vm_entry );
@@ -11,10 +13,4 @@ namespace vm
         auto vm_handler_table = vm::handler::table::get( vm_entry );
         vm::handler::get_all( module_base, image_base, vm_entry, vm_handler_table, vm_handlers );
     }
-
-    ctx_t::ctx_t( std::vector< vm::handler::handler_t > &vm_handlers, zydis_routine_t &vm_entry,
-                  zydis_routine_t &calc_jmp, vmp2::exec_type_t exec_type )
-        : vm_handlers( vm_handlers ), vm_entry( vm_entry ), calc_jmp( calc_jmp ), exec_type( exec_type )
-    {
-    }
 } // namespace vm

src/vminstrs.cpp

@@ -196,5 +196,78 @@ namespace vm
 
             return result;
         }
+
+        std::optional< jcc_data > get_jcc_data( vm::ctx_t &vmctx, code_block_t &code_block )
+        {
+            // there is no branch for this as this is a vmexit...
+            if ( code_block.vinstrs.back().mnemonic_t == vm::handler::VMEXIT )
+                return {};
+
+            // find the last LCONSTDW... the imm value is the JMP xor decrypt key...
+            // we loop backwards here (using rbegin and rend)...
+            auto result = std::find_if( code_block.vinstrs.rbegin(), code_block.vinstrs.rend(),
+                                        []( const vm::instrs::virt_instr_t &vinstr ) -> bool {
+                                            auto profile = vm::handler::get_profile( vinstr.mnemonic_t );
+                                            return profile && profile->mnemonic == vm::handler::LCONSTDW;
+                                        } );
+
+            jcc_data jcc;
+            const auto xor_key = static_cast< std::uint32_t >( result->operand.imm.u );
+            const auto &last_trace = code_block.vinstrs.back().trace_data;
+
+            // since result is already a variable and is a reverse itr
+            // im going to be using rbegin and rend here again...
+            //
+            // look for PUSHVSP virtual instructions with two encrypted virtual
+            // instruction rva's ontop of the virtual stack...
+            result = std::find_if( code_block.vinstrs.rbegin(), code_block.vinstrs.rend(),
+                                   [ & ]( const vm::instrs::virt_instr_t &vinstr ) -> bool {
+                                       auto profile = vm::handler::get_profile( vinstr.mnemonic_t );
+                                       if ( profile && profile->mnemonic == vm::handler::PUSHVSP )
+                                       {
+                                           const auto possible_block_1 =
+                                               code_block_addr( vmctx, vinstr.trace_data.vsp.qword[ 0 ] ^ xor_key );
+
+                                           const auto possible_block_2 =
+                                               code_block_addr( vmctx, vinstr.trace_data.vsp.qword[ 1 ] ^ xor_key );
+
+                                           // if this returns too many false positives we might have to get
+                                           // our hands dirty and look into trying to emulate each branch
+                                           // to see if the first instruction is an SREGQ...
+                                           return possible_block_1 > vmctx.module_base &&
+                                                  possible_block_1 < vmctx.module_base + vmctx.image_size &&
+                                                  possible_block_2 > vmctx.module_base &&
+                                                  possible_block_2 < vmctx.module_base + vmctx.image_size;
+                                       }
+
+                                       return false;
+                                   } );
+
+            // if there is not two branches...
+            if ( result == code_block.vinstrs.rend() )
+            {
+                jcc.block_rva[ 0 ] = code_block_addr( vmctx, last_trace );
+
+                jcc.has_jcc = false;
+                jcc.type = jcc_type::absolute;
+            }
+            // else there are two branches...
+            else
+            {
+                jcc.block_rva[ 0 ] =
+            }
+
+            return jcc;
+        }
+
+        std::uintptr_t code_block_addr( const vm::ctx_t &ctx, const vmp2::v2::entry_t &entry )
+        {
+            return ( ( entry.vsp.qword[ 0 ] + ctx.image_base & ~0xFFFFFFFFull ) - ctx.image_base ) + ctx.module_base;
+        }
+
+        std::uintptr_t code_block_addr( const vm::ctx_t &ctx, const std::uint32_t lower_32bits )
+        {
+            return ( ( lower_32bits + ctx.image_base & ~0xFFFFFFFFull ) - ctx.image_base ) + ctx.module_base;
+        }
     } // namespace instrs
 } // namespace vm