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2020-10-11 00:35:02 -05:00 · 2020-10-11 00:35:02 -05:00 · e16e932b83
parent a447a29113
commit e16e932b83
1 changed files with 112 additions and 0 deletions
--- a/Trick.txt
+++ b/Trick.txt
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+;%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+; Fake EP trick
+;%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+; The idea is simple: After loading our program, we change the loaded PE image entry point 
+; dynamically to another routine inside our code (In this example is a simple messagebox).
+;
+; So, when the reverse guy dumps it will get the changed EP and change the PE behaviour 
+; when the dumped file run. This is just an educational trick with PE headers for my 
+; students understand better the PE Format in a practical way on malware analysis classes.
+;
+; This trick defeats: 
+;       - Process Dump v2.1 (https://github.com/glmcdona/Process-Dump)
+;       - OllyDumpEx
+;       - Every dumper that grabs info from loaded PE header
+; 
+; We move the file location to defeat Scylla too.
+;
+; SWaNk 2020 - VX 
+;%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+format PE GUI 4.0
+
+entry start
+
+;%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+; includes
+;%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+include '%fasm%\INCLUDE\win32a.inc'
+
+;%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+section '.text' code readable writeable executable
+;%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+        ; if the file was dumped from memory, with one tool that grab the loaded image, 
+        ; the EP will chage to this instruction
+        push    0
+        push    szTitle
+        push    szFuckOff
+        push    0
+        call    [MessageBoxA]
+
+        push    0
+        call    [ExitProcess]
+
+start:
+        invoke GetModuleHandleA, 0                              ;get imageBase
+        mov     [mHandle], eax
+        
+        mov     ebx, eax                                        ;save into ebx
+        add     ebx, 0xa8                                       ;EP 
+
+        invoke VirtualProtect, ebx, 4, PAGE_EXECUTE_READWRITE, Old
+        mov     byte[ebx], 0x00                                 ;Change EP to our joke payload
+        invoke VirtualProtect, ebx, 4, PAGE_EXECUTE_READ, Old
+
+        ;Now we rename the file so Scylla can't find it on disk (MoveFileA)
+
+        invoke GetModuleFileNameA,0,szfileName, 255             ; return length in eax
+        add eax, szfileName                                     ; eax now is in the end of the PE filename
+
+        ;Find for the first '\' from backwards to grab the filename
+        @@:
+        dec     eax
+        cmp     byte[eax],'\'             
+        jne     @B
+        inc     eax                                             ;skip slash 
+        mov     ebx, eax                                        ;save to rename file back
+
+        invoke MoveFileA, eax, tmpName, NULL
+
+        ;normal behaviour, just a messagebox, if the file is dumped here the trap is set
+        push    0
+        push    szTitle
+        push    szExample
+        push    0
+        call    [MessageBoxA]
+
+        ;rename to the original name
+
+        invoke MoveFileA, tmpName, ebx, NULL
+
+        push    0
+        call    [ExitProcess]
+
+error:
+        push    0
+        call    [ExitProcess]
+
+;%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+section '.data' data readable writeable
+;%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+szExample       db      'Original file',0
+szFuckOff       db      'Hands off asshole',0
+szTitle         db      'Fake EP trick',0
+mHandle         dd      ?
+szfileName      rb      250
+tmpName         db      "1.exe",0
+Old             dd      ?
+
+;%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+data import
+        library kernel,'KERNEL32.DLL',\
+                user32,'USER32.DLL'
+
+        import user32,  MessageBoxA,'MessageBoxA'
+        import kernel,  ExitProcess,'ExitProcess',\
+                        GetModuleHandleA,'GetModuleHandleA',\
+                        GetModuleFileNameA,'GetModuleFileNameA',\
+                        MoveFileA,'MoveFileA',\
+                        VirtualProtect,'VirtualProtect'
+ 
+end data