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| 1 | *** DLL operations *** | |
| 2 | ||
| 3 | 1] Checks to see if task already running by attempting to open mutex with name MsWinZonesCacheCounterMutexA | |
| 4 | If already exists, app exits | |
| 5 | ||
| 6 | 2] Obtains name of current directory. | |
| 7 | ||
| 8 | 3] Reads 780 bytes of information from c.wnry which it expects in current directory. This has | |
| 9 | bitcoin and TOR info. | |
| 10 | ||
| 11 | 4] Checks if running as LocalSystem. Sets a flag used later when running @[email protected] | |
| 12 | ||
| 13 | 5] Resolves api from advapi32.dll | |
| 14 | ||
| 15 | CryptAcquireContextA | |
| 16 | CryptImportKey | |
| 17 | CryptDestroyKey | |
| 18 | CryptEncrypt | |
| 19 | CryptDecrypt | |
| 20 | CryptGenKey | |
| 21 | ||
| 22 | 6] Resolves api from kernel32.dll | |
| 23 | ||
| 24 | CreateFileW | |
| 25 | WriteFile | |
| 26 | ReadFile | |
| 27 | MoveFileW | |
| 28 | MoveFileExW | |
| 29 | DeleteFileW | |
| 30 | CloseHandle | |
| 31 | ||
| 32 | 7] Initializes names of files | |
| 33 | ||
| 34 | 00000000.res - C2 communications | |
| 35 | 00000000.pky - Public key used by the ransomware to encrypt the generated AES keys that are used to encrypt the user’s files | |
| 36 | 00000000.eky - Encryption key for the t.wnry file which stores the actual file encryption component used by the ransomware. | |
| 37 | It is encrypted using the public key that belongs to a private key embedded inside the ransomware. | |
| 38 | ||
| 39 | ||
| 40 | 8] creates mutex with name MsWinZonesCacheCounterMutexA and sets the security | |
| 41 | ACL to allow EVERYONE full access | |
| 42 | ||
| 43 | ||
| 44 | 9] tries to open 00000000.dky. if available, will import key into Crypto API object. | |
| 45 | presumably this would be decryption key from the authors of ransomware.. | |
| 46 | ||
| 47 | ||
| 48 | 10] if cannot open *.dky file, will generate new RSA key pair of 2048-bits. | |
| 49 | Public key is exported as blob and saved to 00000000.pky | |
| 50 | Private key is exported as blob and encrypted with ransomware public key before being saved to 00000000.eky | |
| 51 | ||
| 52 | The RSA public key used to encrypt the users RSA key pair is embedded inside the DLL. | |
| 53 | ||
| 54 | unsigned char wc_key1[] = | |
| 55 | {
| |
| 56 | 0x06, 0x02, 0x00, 0x00, 0x00, 0xA4, 0x00, 0x00, 0x52, 0x53, | |
| 57 | 0x41, 0x31, 0x00, 0x08, 0x00, 0x00, 0x01, 0x00, 0x01, 0x00, | |
| 58 | 0x75, 0x97, 0x4C, 0x3B, 0x84, 0x46, 0xDE, 0x2C, 0x2A, 0xF4, | |
| 59 | 0x95, 0xA8, 0x5D, 0xC0, 0xCD, 0x6D, 0xDA, 0xD7, 0xD4, 0x92, | |
| 60 | 0x1E, 0x13, 0x82, 0x34, 0x6A, 0x70, 0x8D, 0x8F, 0x7C, 0xF7, | |
| 61 | 0x04, 0x92, 0x55, 0x7F, 0xF1, 0xA2, 0x27, 0xB2, 0x9E, 0x41, | |
| 62 | 0xAC, 0x90, 0x80, 0x91, 0x18, 0x93, 0xC2, 0xB1, 0x7B, 0xAD, | |
| 63 | 0x2B, 0xF3, 0xFF, 0xAF, 0xDB, 0x2B, 0x51, 0xBE, 0x1D, 0xA3, | |
| 64 | 0x27, 0xE3, 0xA7, 0x57, 0x08, 0x5A, 0xBE, 0xC1, 0x1D, 0xF6, | |
| 65 | 0x04, 0xF8, 0x1C, 0xBE, 0x5B, 0xB1, 0x67, 0xFB, 0xE4, 0xC8, | |
| 66 | 0xDA, 0x75, 0x00, 0x70, 0xB1, 0x17, 0x70, 0x24, 0x6C, 0x09, | |
| 67 | 0x63, 0x74, 0xAC, 0x4B, 0x0A, 0x1D, 0x71, 0xAE, 0x7F, 0xAE, | |
| 68 | 0x65, 0xB8, 0xC5, 0x86, 0x79, 0xC5, 0x7E, 0x9F, 0x98, 0x60, | |
| 69 | 0x4C, 0x52, 0xB9, 0x29, 0x62, 0xCB, 0x23, 0x29, 0xED, 0x31, | |
| 70 | 0x91, 0x74, 0x7B, 0x7B, 0x0B, 0x26, 0x1B, 0xF2, 0x7D, 0x67, | |
| 71 | 0xBF, 0xDA, 0x7A, 0x40, 0xDA, 0xF2, 0x61, 0x4D, 0x94, 0xA5, | |
| 72 | 0x7D, 0xAD, 0x59, 0x6B, 0xAD, 0x9E, 0xA3, 0x3A, 0x39, 0xC6, | |
| 73 | 0x5B, 0x6E, 0x9F, 0xD2, 0xBB, 0x36, 0xB5, 0xF5, 0xD2, 0x65, | |
| 74 | 0xF5, 0x2C, 0x30, 0xD8, 0xC1, 0x17, 0xBD, 0xAF, 0x28, 0x00, | |
| 75 | 0x96, 0x20, 0x46, 0xA7, 0x2D, 0x62, 0x03, 0x0C, 0xD7, 0xD0, | |
| 76 | 0x75, 0xA0, 0x0B, 0x07, 0xEA, 0xD4, 0x1F, 0xCA, 0xE8, 0xD9, | |
| 77 | 0x4E, 0xDB, 0x38, 0xF2, 0x26, 0x75, 0xCB, 0x12, 0xA6, 0x88, | |
| 78 | 0x70, 0x9B, 0xE1, 0xEA, 0x32, 0xDC, 0xF8, 0x71, 0x72, 0x50, | |
| 79 | 0x41, 0xE6, 0x17, 0x81, 0x68, 0x27, 0x42, 0x8E, 0xDF, 0xE5, | |
| 80 | 0xDE, 0xA1, 0x72, 0xD9, 0x3B, 0xFB, 0xE5, 0x9D, 0x30, 0x11, | |
| 81 | 0x69, 0x92, 0xCD, 0x60, 0x2B, 0xE2, 0xD5, 0x46, 0x3C, 0x28, | |
| 82 | 0xCF, 0x9D, 0x30, 0x4A, 0xF7, 0xAD, 0xB9, 0xFB, 0x0F, 0x91, | |
| 83 | 0xFE, 0x2E, 0xBE, 0x18, 0xF1, 0xCE | |
| 84 | }; | |
| 85 | ||
| 86 | The AES-128 key generated for each file is derived from CryptGenRandom which | |
| 87 | is cryptographically secure and is not known to have any weakness. | |
| 88 | ||
| 89 | The AES keys are encrypted using the users public key in *.pky. | |
| 90 | In order to decrypt, we need the users private key which is | |
| 91 | encrypted using a public key owned by the ransomware authors. | |
| 92 | ||
| 93 | Presumably what authors do is decrypt the users private key in *.eky file | |
| 94 | using their private key and then send the user a *.dky file | |
| 95 | to decrypt files. |
