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| import os | |
| import sys | |
| ''' | |
| Decodes PST encoded .txt attachments from Exchange Mailbox | |
| RULE: WEBSHELL_ASPX_Exchange_Encoded_Mailbox_Attachment_Aug21 | |
| ''' | |
| def decode(payload): | |
| mpbbCryptFrom512 = [ | |
| 65, 54, 19, 98, 168, 33, 110, 187, 244, 22, 204, 4, 127, 100, 232, 93, | |
| 30, 242, 203, 42, 116, 197, 94, 53, 210, 149, 71, 158, 150, 45, 154, 136, | |
| 76, 125, 132, 63, 219, 172, 49, 182, 72, 95, 246, 196, 216, 57, 139, 231, | |
| 35, 59, 56, 142, 200, 193, 223, 37, 177, 32, 165, 70, 96, 78, 156, 251, | |
| 170, 211, 86, 81, 69, 124, 85, 0, 7, 201, 43, 157, 133, 155, 9, 160, | |
| 143, 173, 179, 15, 99, 171, 137, 75, 215, 167, 21, 90, 113, 102, 66, 191, | |
| 38, 74, 107, 152, 250, 234, 119, 83, 178, 112, 5, 44, 253, 89, 58, 134, | |
| 126, 206, 6, 235, 130, 120, 87, 199, 141, 67, 175, 180, 28, 212, 91, 205, | |
| 226, 233, 39, 79, 195, 8, 114, 128, 207, 176, 239, 245, 40, 109, 190, 48, | |
| 77, 52, 146, 213, 14, 60, 34, 50, 229, 228, 249, 159, 194, 209, 10, 129, | |
| 18, 225, 238, 145, 131, 118, 227, 151, 230, 97, 138, 23, 121, 164, 183, 220, | |
| 144, 122, 92, 140, 2, 166, 202, 105, 222, 80, 26, 17, 147, 185, 82, 135, | |
| 88, 252, 237, 29, 55, 73, 27, 106, 224, 41, 51, 153, 189, 108, 217, 148, | |
| 243, 64, 84, 111, 240, 198, 115, 184, 214, 62, 101, 24, 68, 31, 221, 103, | |
| 16, 241, 12, 25, 236, 174, 3, 161, 20, 123, 169, 11, 255, 248, 163, 192, | |
| 162, 1, 247, 46, 188, 36, 104, 117, 13, 254, 186, 47, 181, 208, 218, 61 | |
| ] | |
| return bytes(mpbbCryptFrom512[i] for i in payload) | |
| if len(sys.argv) != 2: | |
| print('Provide folder with encoded .txt attachments') | |
| exit(1) | |
| for root, dirs, files in os.walk(sys.argv[1]): | |
| for file in files: | |
| if file.endswith('.txt'): | |
| full_path = os.path.join(root, file) | |
| with open(full_path, 'rb') as f: | |
| payload = f.read() | |
| with open(full_path + '_decoded', 'wb') as d: | |
| d.write(decode(payload)) | |
| print('Decoded file', file) |
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