chained-forensic-extraction_20260101_011957

{"output": "total 16\ndrwxr-xr-x 1 root root 4096 Mar  4 09:22 .\ndrwxr-xr-x 1 root root 4096 Apr 23 09:37 ..\ndrwxr-xr-x 2 root root 4096 Mar  4 09:22 data\ndrwxr-xr-x 2 root root 4096 Mar  4 09:22 output", "exit_code": 0, "error": null}

I'll solve this chained forensic extraction step by step. Let me start by exploring the environment and examining the artifact file.

→ terminal({"command": "cd /app && ls -la", "timeout": 30})

{"output": "total 12\ndrwxr-xr-x 2 root root 4096 Mar  4 09:22 .\ndrwxr-xr-x 1 root root 4096 Mar  4 09:22 ..\n-rw-r--r-- 1 root root  957 Mar  4 09:22 artifact.bin", "exit_code": 0, "error": null}

{"output": "bash: line 3: file: command not found", "exit_code": 127, "error": null}

{"output": "bash: line 3: hexdump: command not found", "exit_code": 0, "error": null}

{"bytes_written": 696, "dirs_created": true}

Let me use Python to examine the file:

→ write_file({"path": "/app/stage1.py", "content": "#!/usr/bin/env python3\nimport sys\n\n# Read the artifact file\nwith open('/app/data/artifact.bin', 'rb') as f:\n    data = f.read()\n\nprint(f\"File size: {len(data)} bytes\")\n\n# Search for ZIP signatures (0x504B0304 = PK\\x03\\x04)\nzip_sig = b'\\x50\\x4B\\x03\\x04'\noffsets = []\nfor i in range(len(data) - len(zip_sig)):\n    if data[i:i+len(zip_sig)] ==…)

{"output": "File size: 957 bytes\nFound ZIP signature at offset: 80 (0x00000050)\nFound ZIP signature at offset: 336 (0x00000150)\n\nTotal ZIP signatures found: 2\n\nStage 1 Results:\nfirst_zip_offset: 80\nsecond_zip_offset: 336", "exit_code": 0, "error": null}

{"bytes_written": 2632, "dirs_created": true}

Perfect! Now let me extract the second ZIP archive and examine its contents:

→ write_file({"path": "/app/stage2.py", "content": "#!/usr/bin/env python3\nimport zipfile\nimport io\nimport struct\nimport zlib\n\n# Extract the second ZIP from the artifact\nwith open('/app/data/artifact.bin', 'rb') as f:\n    data = f.read()\n\n# Second ZIP starts at offset 336\nsecond_zip_data = data[336:]\n\n# Write to temp file and extract\nwith open('/tmp/second_zip.zip', 'wb') as f:\n    f.write(secon…)

{"output": "Extracted files: ['hidden.png']\n\nPNG file size: 503 bytes\n\nFound tEXt chunk:\n  Offset: 33\n  Length: 424\n  Text: Comment\u0000LSgsK3VvM28uKCApcRdxEW48GDExAmkMLhdpLmM5aSMscRgTI3FoETwrcT4tKDQXbDltMC0XaSkyYiBtMGw/CDNiDj0tFhgfPAACaWk/MzZtbxgJbTk1biIYNSI7GB0pM2MgaTA/Chs/Kiw8aG0zKXU8HD0tNQMKMyo2PmIYAws8Khw9NgwOKW4ZNCtvFjMtIxcpPCNtMw11PDY+LShxEm0MGTMgcTQLbDl1MDsYbCt1PWgLIjULCj1jbG1iMmgdLyhsEHENCyBvDTsiNwI3DHU8NmwwAykLbxlsPmlxbQsyKWgoaT5pNG09cWwtDBgfPAACaWk/MzZsORgJbTk1biIYNSI7KB1xIHFsAGwMPzYgMjYCbRgdbz08LXE2AjUDPWIOPmIYAww8ACAVMAN1KT0qLDwiMGdn\n  Stored CRC: 3890872c\n  Calculated CRC: 3890872c\n  CRC valid: True\n\nStage 2 Results:\npng_text_offset: 33\npng_crc_valid: True\npng_extracted_text: Comment\u0000LSgsK3VvM28uKCApcRdxEW48GDExAmkMLhdpLmM5aSMscRgTI3FoETwrcT4tKDQXbDltMC0XaSkyYiBtMGw/CDNiDj0tFhgfPAACaWk/MzZtbxgJbTk1biIYNSI7GB0pM2MgaTA/Chs/Kiw8aG0zKXU8HD0tNQMKMyo2PmIYAws8Khw9NgwOKW4ZNCtvFjMtIxcpPCNtMw11PDY+LShxEm0MGTMgcTQLbDl1MDsYbCt1PWgLIjULCj1jbG1iMmgdLyhsEHENCyBvDTsiNwI3DHU8NmwwAykLbxlsPmlxbQsyKWgoaT5pNG09cWwtDBgfPAACaWk/MzZsORgJbTk1biIYNSI7KB1xIHFsAGwMPzYgMjYCbRgdbz08LXE2AjUDPWIOPmIYAww8ACAVMAN1KT0qLDwiMGdn", "exit_code": 0, "error": null}

{"bytes_written": 2634, "dirs_created": true}

Great! Now I have the encoded text. Let me proceed to Stage 3 to decode the 3-layer encoding chain:

→ write_file({"path": "/app/stage3.py", "content": "#!/usr/bin/env python3\nimport base64\nimport re\n\n# The encoded text from Stage 2\nencoded_text = \"LSgsK3VvM28uKCApcRdxEW48GDExAmkMLhdpLmM5aSMscRgTI3FoETwrcT4tKDQXbDltMC0XaSkyYiBtMGw/CDNiDj0tFhgfPAACaWk/MzZtbxgJbTk1biIYNSI7GB0pM2MgaTA/Chs/Kiw8aG0zKXU8HD0tNQMKMyo2PmIYAws8Khw9NgwOKW4ZNCtvFjMtIxcpPCNtMw11PDY+LShxEm0MGTMgcTQLbDl1MDsYbCt1PWgLIjULCj1jbG1iMmgdLyh…)

{"output": "Found potential key: 0\n  XOR decoded: LSgsK3VvM28uKCApcRdxEW48GDExAmkMLhdpLmM5aSMscRgTI3...\n  ROT13 decoded: YFtfX3IiZ28hXPNcpEqkRJ48TQRkNzxZYuqcYzZ5nFZfpEtGV3...\n\nStage 3 Results:\nencoding_chain: ['rot13', 'xor', 'base64']\nxor_key: 0\ndecoded_intermediate: YFtfX3IiZ28hXPNcpEqkRJ48TQRkNzxZYuqcYzZ5nFZfpEtGV3SbRGjepG4gXQDKoQygZP0KnFxlLvOgZTj/PQAvQw0gSutsCNNPnJx/ZmMgoktWoGx1ovVLAFV7TO0cZ2ZtnGN/Puf/Xvj8nT0mXKH8UQ0gADZXZlb2CzVLNjf8Xuj9AtjBXJ4MAPgiSwZgVkpcCPAgZj11CQL+YFukRz0ZTGZtpGDYoQy1ZQfLoPg1CJtYVwHYPw1woT1vZztqYlufRURAPlOiQGfvAjV3QUH8AzjjNlxYokyfCzykoDflXJtbnG5cAT09pJjgQOtsCNNPnJx/ZmMfBEtWoGx1ovVLAFV7XO1kVUSfNTjZCmLtZwLPoEtqom08YKR2NwHQCJVBCzVLNjj8NPNIZNA1XG0dYQjvZTqa\n  (Valid Base64)", "exit_code": 0, "error": null}

{"bytes_written": 2305, "dirs_created": true}

Perfect! Now let me proceed to Stage 4 to decrypt the Base64-decoded data using the known-plaintext attack:

→ write_file({"path": "/app/stage4.py", "content": "#!/usr/bin/env python3\nimport base64\n\n# The decoded intermediate from Stage 3 (Base64 string)\ndecoded_intermediate = \"YFtfX3IiZ28hXPNcpEqkRJ48TQRkNzxZYuqcYzZ5nFZfpEtGV3SbRGjepG4gXQDKoQygZP0KnFxlLvOgZTj/PQAvQw0gSutsCNNPnJx/ZmMgoktWoGx1ovVLAFV7TO0cZ2ZtnGN/Puf/Xvj8nT0mXKH8UQ0gADZXZlb2CzVLNjf8Xuj9AtjBXJ4MAPgiSwZgVkpcCPAgZj11CQL+YFukRz0ZTGZtpGDYoQy1ZQfLoPg1CJ…)

{"output": "Ciphertext length: 312 bytes\nCiphertext (first 50 bytes): b'`[__r\"go!\\\\\\xf3\\\\\\xa4J\\xa4D\\x9e<M\\x04d7<Yb\\xea\\x9cc6y\\x9cV_\\xa4KFWt\\x9bDh\\xde\\xa4n ]\\x00\\xca\\xa1\\x0c'\n\nTrying key length 1: 33\n  Decrypted start: b'ShllA\\x11T\\\\\\x12o\\xc0o\\x97y\\x97w\\xad\\x0f~7W\\x04\\x0fjQ\\xd9\\xafP\\x05J\\xafel\\x97xudG\\xa8w[\\xed\\x97]\\x13n3\\xf9\\x92?'\n\nTrying key length 2: 331e\n  Decrypted start: b'SElAA<Tq\\x12B\\xc0B\\x97T\\x97Z\\xad\"~\\x1aW)\\x0fGQ\\xf4\\xaf}\\x05g\\xafHl\\xbaxXdj\\xa8Z[\\xc0\\x97p\\x13C3\\xd4\\x92\\x12'\n\nTrying key length 3: 331e1c\n  Decrypted start: b'SECll>Tq=o\\xed@\\x97T\\xb8w\\x80 ~\\x1ax\\x04\"EQ\\xf4\\x80P(e\\xafHC\\x97UZdj\\x87wv\\xc2\\x97p<n\\x1e\\xd6\\x92\\x12'\n\nTrying key length 4: 331e1c0d\n  Decrypted start: b'SECRA<{b\\x12B\\xefQ\\x97T\\xb8I\\xad\"Q\\tW) TQ\\xf4\\x80n\\x05g\\x80[l\\xbaWKdj\\x87I[\\xc0\\xb8c\\x13C\\x1c\\xc7\\x92\\x12'", "exit_code": 0, "error": null}

{"bytes_written": 2350, "dirs_created": true}

None of the keys worked perfectly. Let me try a different approach - maybe the known plaintext doesn't start at position 0, or I need to search for it within the decrypted text:

→ write_file({"path": "/app/stage4_v2.py", "content": "#!/usr/bin/env python3\nimport base64\n\n# The decoded intermediate from Stage 3 (Base64 string)\ndecoded_intermediate = \"YFtfX3IiZ28hXPNcpEqkRJ48TQRkNzxZYuqcYzZ5nFZfpEtGV3SbRGjepG4gXQDKoQygZP0KnFxlLvOgZTj/PQAvQw0gSutsCNNPnJx/ZmMgoktWoGx1ovVLAFV7TO0cZ2ZtnGN/Puf/Xvj8nT0mXKH8UQ0gADZXZlb2CzVLNjf8Xuj9AtjBXJ4MAPgiSwZgVkpcCPAgZj11CQL+YFukRz0ZTGZtpGDYoQy1ZQfLoPg…)

{"output": "Ciphertext length: 312 bytes\n\nTrying key length 1...\n\nTrying key length 2...\n\nTrying key length 3...\n\nTrying key length 4...\n\nNo key found that produces the known plaintext!", "exit_code": 0, "error": null}

{"bytes_written": 2237, "dirs_created": true}

Let me try a different approach - maybe I need to check if the ciphertext contains the known plaintext pattern in a different way:

→ write_file({"path": "/app/stage4_v3.py", "content": "#!/usr/bin/env python3\nimport base64\n\n# The decoded intermediate from Stage 3 (Base64 string)\ndecoded_intermediate = \"YFtfX3IiZ28hXPNcpEqkRJ48TQRkNzxZYuqcYzZ5nFZfpEtGV3SbRGjepG4gXQDKoQygZP0KnFxlLvOgZTj/PQAvQw0gSutsCNNPnJx/ZmMgoktWoGx1ovVLAFV7TO0cZ2ZtnGN/Puf/Xvj8nT0mXKH8UQ0gADZXZlb2CzVLNjf8Xuj9AtjBXJ4MAPgiSwZgVkpcCPAgZj11CQL+YFukRz0ZTGZtpGDYoQy1ZQfLoPg…)

{"output": "Ciphertext length: 312 bytes\nCiphertext (hex): 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\n\nTrying key length 1...\n\nTrying key length 2...\n\nTrying key length 3...\n\nTrying key length 4...\n\nNo key found!", "exit_code": 0, "error": null}

{"bytes_written": 2042, "dirs_created": true}

Let me try a different approach. Maybe I need to look for ASCII text patterns in the decrypted data:

→ write_file({"path": "/app/stage4_v4.py", "content": "#!/usr/bin/env python3\nimport base64\n\n# The decoded intermediate from Stage 3 (Base64 string)\ndecoded_intermediate = \"YFtfX3IiZ28hXPNcpEqkRJ48TQRkNzxZYuqcYzZ5nFZfpEtGV3SbRGjepG4gXQDKoQygZP0KnFxlLvOgZTj/PQAvQw0gSutsCNNPnJx/ZmMgoktWoGx1ovVLAFV7TO0cZ2ZtnGN/Puf/Xvj8nT0mXKH8UQ0gADZXZlb2CzVLNjf8Xuj9AtjBXJ4MAPgiSwZgVkpcCPAgZj11CQL+YFukRz0ZTGZtpGDYoQy1ZQfLoPg…)

{"output": "Trying key length 1...\n  Potential key: 00, ASCII ratio: 34/50\n  Potential key: 01, ASCII ratio: 34/50\n  Potential key: 02, ASCII ratio: 34/50\n  Potential key: 03, ASCII ratio: 34/50\n  Potential key: 04, ASCII ratio: 34/50\n  Potential key: 05, ASCII ratio: 34/50\n  Potential key: 06, ASCII ratio: 33/50\n  Potential key: 07, ASCII ratio: 34/50\n  Potential key: 08, ASCII ratio: 34/50\n  Potential key: 09, ASCII ratio: 34/50\n  Potential key: 0a, ASCII ratio: 34/50\n  Potential key: 0b, ASCII ratio: 33/50\n  Potential key: 0c, ASCII ratio: 34/50\n  Potential key: 0d, ASCII ratio: 33/50\n  Potential key: 0e, ASCII ratio: 34/50\n  Potential key: 0f, ASCII ratio: 34/50\n  Potential key: 10, ASCII ratio: 33/50\n  Potential key: 11, ASCII ratio: 33/50\n  Potential key: 12, ASCII ratio: 34/50\n  Potential key: 13, ASCII ratio: 34/50\n  Potential key: 14, ASCII ratio: 34/50\n  Potential key: 15, ASCII ratio: 34/50\n  Potential key: 16, ASCII ratio: 34/50\n  Potential key: 17, ASCII ratio: 33/50\n  Potential key: 18, ASCII ratio: 33/50\n  Potential key: 19, ASCII ratio: 34/50\n  Potential key: 1a, ASCII ratio: 34/50\n  Potential key: 1b, ASCII ratio: 33/50\n  Potential key: 1c, ASCII ratio: 33/50\n  Potential key: 1d, ASCII ratio: 33/50\n  Potential key: 1e, ASCII ratio: 34/50\n  Potential key: 1f, ASCII ratio: 33/50\nTrying key length 2...\nTraceback (most recent call last):\n  File \"/app/stage4_v4.py\", line 22, in <module>\n    test_decrypted += bytes([ciphertext[i] ^ key[i % key_length]])\n                                             ~~~^^^^^^^^^^^^^^^^\nIndexError: index out of range", "exit_code": 1, "error": null}

{"bytes_written": 3420, "dirs_created": true}

Let me fix the indexing error and continue:

→ write_file({"path": "/app/stage4_v5.py", "content": "#!/usr/bin/env python3\nimport base64\n\n# The decoded intermediate from Stage 3 (Base64 string)\ndecoded_intermediate = \"YFtfX3IiZ28hXPNcpEqkRJ48TQRkNzxZYuqcYzZ5nFZfpEtGV3SbRGjepG4gXQDKoQygZP0KnFxlLvOgZTj/PQAvQw0gSutsCNNPnJx/ZmMgoktWoGx1ovVLAFV7TO0cZ2ZtnGN/Puf/Xvj8nT0mXKH8UQ0gADZXZlb2CzVLNjf8Xuj9AtjBXJ4MAPgiSwZgVkpcCPAgZj11CQL+YFukRz0ZTGZtpGDYoQy1ZQfLoPg…)

{"output": "Trying key length 1...\nTrying key length 2...\nTrying key length 3...\nTrying key length 4...\nNo key found!", "exit_code": 0, "error": null}

{"bytes_written": 1916, "dirs_created": true}

Let me try a different approach - maybe I should look at the ciphertext more carefully and try to find patterns:

→ write_file({"path": "/app/analyze_ciphertext.py", "content": "#!/usr/bin/env python3\nimport base64\n\n# The decoded intermediate from Stage 3 (Base64 string)\ndecoded_intermediate = \"YFtfX3IiZ28hXPNcpEqkRJ48TQRkNzxZYuqcYzZ5nFZfpEtGV3SbRGjepG4gXQDKoQygZP0KnFxlLvOgZTj/PQAvQw0gSutsCNNPnJx/ZmMgoktWoGx1ovVLAFV7TO0cZ2ZtnGN/Puf/Xvj8nT0mXKH8UQ0gADZXZlb2CzVLNjf8Xuj9AtjBXJ4MAPgiSwZgVkpcCPAgZj11CQL+YFukRz0ZTGZtpGDYoQ…)

{"output": "Ciphertext analysis:\nLength: 312 bytes\nHex: 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\nPattern 60 repeats at positions: [0, 143, 156, 166, 282] (length 1)\nPattern 5b repeats at positions: [1, 157, 193, 227] (length 1)\nPattern 67 repeats at positions: [6, 96, 189, 202, 273] (length 1)\nPattern 5c repeats at positions: [9, 11, 55, 111, 135, 146, 214, 225, 230, 261, 303] (length 1)\nPattern a4 repeats at positions: [12, 14, 33, 42, 158, 165, 221, 234, 283] (length 1)\nPattern 44 repeats at positions: [15, 39, 196, 265] (length 1)\nPattern 3c repeats at positions: [17, 22, 220, 281] (length 1)\nPattern 64 repeats at positions: [20, 51, 263, 300] (length 1)\nPattern 37 repeats at positions: [21, 127, 223, 285] (length 1)\nPattern 9c repeats at positions: [26, 30, 54, 75, 76, 99, 228, 243, 244] (length 1)\nPattern 63 repeats at positions: [27, 79, 100, 247] (length 1)\nPattern 36 repeats at positions: [28, 118, 126, 213, 294] (length 1)\nPattern 56 repeats at positions: [31, 83, 121, 144, 251] (length 1)\nPattern 4b repeats at positions: [34, 82, 89, 125, 141, 250, 257, 277, 293] (length 1)\nPattern 20 repeats at positions: [44, 68, 80, 116, 149] (length 1)\nPattern 00 repeats at positions: [46, 64, 90, 117, 138, 258] (length 1)\nPattern a1 repeats at positions: [48, 112, 168, 186] (length 1)\nPattern a0 repeats at positions: [50, 59, 84, 174, 222, 252, 276] (length 1)\nPattern 65 repeats at positions: [56, 60, 171, 309] (length 1)\nPattern 38 repeats at positions: [61, 211, 268, 295] (length 1)\nPattern 3d repeats at positions: [63, 109, 151, 160, 187, 232, 233] (length 1)\nPattern 6c repeats at positions: [71, 85, 239, 253] (length 1)\nPattern 08 repeats at positions: [72, 147, 177, 240, 288, 307] (length 1)\nPattern 66 repeats at positions: [78, 97, 120, 150, 163, 246] (length 1)\nPattern a2 repeats at positions: [81, 87, 200, 216, 255, 279] (length 1)\nPattern 6d repeats at positions: [98, 164, 280, 304] (length 1)\nPattern fc repeats at positions: [107, 113, 128, 209, 296] (length 1)\nPattern 35 repeats at positions: [124, 176, 205, 267, 292, 302] (length 1)\nPattern 02 repeats at positions: [132, 154, 204, 274] (length 1)\n\nTrying candidate key: 53\nDecrypted: b\"3\\x08\\x0c\\x0c!q4<r\\x0f\\xa0\\x0f\\xf7\\x19\\xf7\\x17\\xcdo\\x1eW7do\\n1\\xb9\\xcf0e*\\xcf\\x05\\x0c\\xf7\\x18\\x15\\x04'\\xc8\\x17;\\x8d\\xf7=s\\x0eS\\x99\\xf2_\\xf37\\xaeY\\xcf\\x0f6}\\xa0\\xf36k\\xacnS|\\x10^s\\x19\\xb8?[\\x80\\x1c\\xcf\\xcf,50s\\xf1\\x18\\x05\\xf3?&\\xf1\\xa6\\x18S\\x06(\\x1f\\xbeO45>\\xcf\"\n\nTrying candidate key: 5345\nDecrypted: b'3\\x1e\\x0c\\x1a!g4*r\\x19\\xa0\\x19\\xf7\\x0f\\xf7\\x01\\xcdy\\x1eA7ro\\x1c1\\xaf\\xcf&e<\\xcf\\x13\\x0c\\xe1\\x18\\x03\\x041\\xc8\\x01;\\x9b\\xf7+s\\x18S\\x8f\\xf2I\\xf3!\\xaeO\\xcf\\x196k\\xa0\\xe56}\\xacxSj\\x10Hs\\x0f\\xb8)[\\x96\\x1c\\xd9\\xcf:5&s\\xe7\\x18\\x13\\xf3)&\\xe7\\xa6\\x0eS\\x10(\\t\\xbeY4#>\\xd9'\n\nTrying candidate key: 534543\nDecrypted: b\"3\\x1e\\x1c\\x0c7a4*b\\x0f\\xb6\\x1f\\xf7\\x0f\\xe7\\x17\\xdb\\x7f\\x1eA'dy\\x1a1\\xaf\\xdf0s:\\xcf\\x13\\x1c\\xf7\\x0e\\x05\\x041\\xd8\\x17-\\x9d\\xf7+c\\x0eE\\x89\\xf2I\\xe37\\xb8I\\xcf\\x19&}\\xb6\\xe36}\\xbcnEl\\x10Hc\\x19\\xae/[\\x96\\x0c\\xcf\\xd9<5&c\\xf1\\x0e\\x15\\xf3)6\\xf1\\xb0\\x08S\\x108\\x1f\\xa8_4#.\\xcf\"\n\nTrying candidate key: 53454352\nDecrypted: b'3\\x1e\\x1c\\r!g$=r\\x19\\xb0\\x0e\\xf7\\x0f\\xe7\\x16\\xcdy\\x0eV7r\\x7f\\x0b1\\xaf\\xdf1e<\\xdf\\x04\

{"bytes_written": 3522, "dirs_created": true}

Let me try a more systematic approach by looking for the "SECRET_DATA:" pattern in the ciphertext:

→ write_file({"path": "/app/stage4_final.py", "content": "#!/usr/bin/env python3\nimport base64\nimport re\n\n# The decoded intermediate from Stage 3 (Base64 string)\ndecoded_intermediate = \"YFtfX3IiZ28hXPNcpEqkRJ48TQRkNzxZYuqcYzZ5nFZfpEtGV3SbRGjepG4gXQDKoQygZP0KnFxlLvOgZTj/PQAvQw0gSutsCNNPnJx/ZmMgoktWoGx1ovVLAFV7TO0cZ2ZtnGN/Puf/Xvj8nT0mXKH8UQ0gADZXZlb2CzVLNjf8Xuj9AtjBXJ4MAPgiSwZgVkpcCPAgZj11CQL+YFukRz0ZTGZtp…)

{"output": "Trying key length 1...\nTrying key length 2...\nTrying key length 3...\nTrying key length 4...\n\nNo key found that produces the known plaintext!\n\nTrying alternative approach...\nStill no key found!", "exit_code": 0, "error": null}

{"bytes_written": 2833, "dirs_created": true}

Let me try a different approach. Maybe I need to look at the ciphertext more carefully and try to find the pattern manually:

→ write_file({"path": "/app/find_key_manually.py", "content": "#!/usr/bin/env python3\nimport base64\n\n# The decoded intermediate from Stage 3 (Base64 string)\ndecoded_intermediate = \"YFtfX3IiZ28hXPNcpEqkRJ48TQRkNzxZYuqcYzZ5nFZfpEtGV3SbRGjepG4gXQDKoQygZP0KnFxlLvOgZTj/PQAvQw0gSutsCNNPnJx/ZmMgoktWoGx1ovVLAFV7TO0cZ2ZtnGN/Puf/Xvj8nT0mXKH8UQ0gADZXZlb2CzVLNjf8Xuj9AtjBXJ4MAPgiSwZgVkpcCPAgZj11CQL+YFukRz0ZTGZtpGDYoQy…)

{"output": "Ciphertext first 50 bytes:\n00: 0x60 (`)\n01: 0x5b ([)\n02: 0x5f (_)\n03: 0x5f (_)\n04: 0x72 (r)\n05: 0x22 (\")\n06: 0x67 (g)\n07: 0x6f (o)\n08: 0x21 (!)\n09: 0x5c (\\)\n10: 0xf3 (.)\n11: 0x5c (\\)\n12: 0xa4 (.)\n13: 0x4a (J)\n14: 0xa4 (.)\n15: 0x44 (D)\n16: 0x9e (.)\n17: 0x3c (<)\n18: 0x4d (M)\n19: 0x04 (.)\n20: 0x64 (d)\n21: 0x37 (7)\n22: 0x3c (<)\n23: 0x59 (Y)\n24: 0x62 (b)\n25: 0xea (.)\n26: 0x9c (.)\n27: 0x63 (c)\n28: 0x36 (6)\n29: 0x79 (y)\n30: 0x9c (.)\n31: 0x56 (V)\n32: 0x5f (_)\n33: 0xa4 (.)\n34: 0x4b (K)\n35: 0x46 (F)\n36: 0x57 (W)\n37: 0x74 (t)\n38: 0x9b (.)\n39: 0x44 (D)\n40: 0x68 (h)\n41: 0xde (.)\n42: 0xa4 (.)\n43: 0x6e (n)\n44: 0x20 ( )\n45: 0x5d (])\n46: 0x00 (.)\n47: 0xca (.)\n48: 0xa1 (.)\n49: 0x0c (.)\n\nLooking for 'SECRET_DATA:' pattern...\n\nFound 0 possible keys", "exit_code": 0, "error": null}

{"bytes_written": 3377, "dirs_created": true}

Let me try a different approach. Maybe I should look for patterns in the ciphertext that might correspond to common ASCII characters:

→ write_file({"path": "/app/brute_force_key.py", "content": "#!/usr/bin/env python3\nimport base64\n\n# The decoded intermediate from Stage 3 (Base64 string)\ndecoded_intermediate = \"YFtfX3IiZ28hXPNcpEqkRJ48TQRkNzxZYuqcYzZ5nFZfpEtGV3SbRGjepG4gXQDKoQygZP0KnFxlLvOgZTj/PQAvQw0gSutsCNNPnJx/ZmMgoktWoGx1ovVLAFV7TO0cZ2ZtnGN/Puf/Xvj8nT0mXKH8UQ0gADZXZlb2CzVLNjf8Xuj9AtjBXJ4MAPgiSwZgVkpcCPAgZj11CQL+YFukRz0ZTGZtpGDYoQy1Z…)

{"output": "No single-byte key found!\n\nTrying two-byte keys...\nNo two-byte key found!", "exit_code": 0, "error": null}

{"bytes_written": 3542, "dirs_created": true}

Let me try a different approach. Maybe I should look at the ciphertext more carefully and try to find repeating patterns that might correspond to the key:

→ write_file({"path": "/app/analyze_patterns.py", "content": "#!/usr/bin/env python3\nimport base64\nfrom collections import defaultdict\n\n# The decoded intermediate from Stage 3 (Base64 string)\ndecoded_intermediate = \"YFtfX3IiZ28hXPNcpEqkRJ48TQRkNzxZYuqcYzZ5nFZfpEtGV3SbRGjepG4gXQDKoQygZP0KnFxlLvOgZTj/PQAvQw0gSutsCNNPnJx/ZmMgoktWoGx1ovVLAFV7TO0cZ2ZtnGN/Puf/Xvj8nT0mXKH8UQ0gADZXZlb2CzVLNjf8Xuj9AtjBXJ4MAPgiSwZ…)

{"output": "Analyzing ciphertext patterns...\n\nPattern length 1:\n  Pattern 5c repeats 11 times at positions: [9, 11, 55, 111, 135, 146, 214, 225, 230, 261]\n  Pattern a4 repeats 9 times at positions: [12, 14, 33, 42, 158, 165, 221, 234, 283]\n  Pattern 9c repeats 9 times at positions: [26, 30, 54, 75, 76, 99, 228, 243, 244]\n  Pattern 4b repeats 9 times at positions: [34, 82, 89, 125, 141, 250, 257, 277, 293]\n  Pattern a0 repeats 7 times at positions: [50, 59, 84, 174, 222, 252, 276]\n\nTrying to derive key from patterns...\nMost common byte in first 100: 0x9c (156) appears 6 times", "exit_code": 0, "error": null}