MicroCorruption/18-Chernobyl/Notes

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Hash Table, plus one full box:
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0 1 2 3 4 5 6 7 8 9 a b c d e f
5000:[0050 1050 1500]0b00 0300 0500 1650 2c50 .P.P.........P,P
5010:[0050 2650 2100]4250 a250 0251 6251 c251 .P&P!.BP.P.QbQ.Q
5020: 2252 8252 e252[1050 3c50 2100]0b00 0000 "R.R.R.P<P!.....
5030: 0000 0000 0000 0000 0000 0000[2650 9c50 ............&P.P
5040: b500]4141 4141 4141 4141 4141 4141 4141 ..AAAAAAAAAAAAAA
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5050: 4100 e004 4141 4141 4141 4141 4141 4141 A...AAAAAAAAAAAA
5060: 4141 4100 e004 4141 4141 4141 4141 4141 AAA...AAAAAAAAAA
5070: 4141 4141 4100 e004 4141 4141 4141 4141 AAAAA...AAAAAAAA
5080: 4141 4141 4141 4100 e004 4141 4141 4141 AAAAAAA...AAAAAA
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5090: 4141 4141 4141 4141 4100 e004[4141 4141 AAAAAAAAA...AAAA ; wait a second
50a0: 4141]4141 4141 4141 4141 4100 e004 4141 AAAAAAAAAAA...AA
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50b0: 4141 4141 4141 4141 4141 4141 4100 e004 AAAAAAAAAAAAA...
50c0: 4141 4141 4141 4141 4141 4141 4141 4100 AAAAAAAAAAAAAAA.
50d0: e004 4141 4141 4141 4141 4141 4141 4141 ..AAAAAAAAAAAAAA
50e0: 4100 e004 4141 4141 4141 4141 4141 4141 A...AAAAAAAAAAAA
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50f0: 4141 4100 e004 4141 4141 4800[9c50 5c51 AAA...AAAAH..P\Q
5100: b500]0000 0000 e004 0000 0000 0000 0000 ................
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Heap metadata @ 2400: 0050 0080 0000
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Heap start: 0x5000
Heap size: 0x8000 (0x5000-0xD000)
Hash Table Header:
Hash table header metadata @ 5000: 0050 1050 1500
[ Prev: 0x5000, Next: 0x5010, Size: 0x000a ] ; malloc block-header ({size:15,status:1})
Data: 0b00 0300 0500 1650 2c50
00: 000b: Number of registered users(?)
02: 0003: Parameter 1 (Box bitmask = 2^(<3>+1) - 1)
04: 0005: Parameter 2 (Rightshift?)
06: 5016: & Box Pointer List
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08: 502c: & Per-box User Count List
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Box Pointer List:
Box list header metadata @ 5010: 0050 2650 2100
[ Prev: 5000, Next: 5026, Size: 0010 ]
Data: 4250 a250 0251 6251 c251 2252 8252 e252
00: 5042 & Box 0
02: 50a2 & Box 1
04: 5102 & Box 2
06: 5162 & Box 3
08: 51c2 & Box 4
0a: 52c2 & Box 5
0c: 5282 & Box 6
0e: 52e2 & Box 7
Other Data Section (?)
Section header metadata @ 5026: 1050 3c50 2100
[ Prev: 5010, Next: 503c, Size: 0010 ]
Data: 0a00 0000 0000 0000 0000 0000 0000 0000
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for c in ['1', '9', 'A', 'I', 'Q', '0', '8', '@', 'H', 'P', 'AAAAAAAAAAAAAAAA', '']:
print(f'new {c} ;',end="")
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Malloc:
- Checks to make sure next pointer is always ASCENDING
- Does not check prev pointer!!!!
The Exploit:
- Overwrite the prev pointer of a block so that it points to ~ the return address on stack
- Overwrite the size parameter so that, when added to the return address, it places pc somewhere nice
- Place pc into a payload on the stack
- INT 0x7f