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Can decrypt the user privatekey (and files) if malware privatekey (!)…
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… and user encrypted privatekey are provided
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@gentilkiwi
gentilkiwi committed May 17, 2017
1 parent 959bcf0 commit 6d639a0
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170 changes: 133 additions & 37 deletions wanadecrypt.c
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Original file line number Diff line number Diff line change
Expand Up @@ -12,10 +12,14 @@
Licence : https://creativecommons.org/licenses/by/4.0/
*/
#include <Windows.h>
#include <Shlwapi.h>
#include <stdio.h>

#define RSA_2048_ENC 256 // 2048 / 8
#define WANA_MAGIC ((ULONGLONG) 0x21595243414e4157) // WANACRY!
#define RSA_ENC_SIZE (RSA_2048_ENC * 5)
#define RSA_DEC_SIZE 1172
#define RSA_BAD_PAD 1225

typedef struct _WANA_FORMAT {
ULONGLONG magic; // WANA_MAGIC
Expand All @@ -31,76 +35,168 @@ typedef struct _GENERICKEY_BLOB {
DWORD dwKeyLen;
} GENERICKEY_BLOB, *PGENERICKEY_BLOB;

typedef struct _ENC_PRIV_KEY {
DWORD totalBytes;
BYTE data[ANYSIZE_ARRAY][RSA_2048_ENC];
} ENC_PRIV_KEY, *PENC_PRIV_KEY;

typedef struct _DEC_PRIV_KEY {
DWORD totalBytes;
BYTE data[ANYSIZE_ARRAY];
} DEC_PRIV_KEY, *PDEC_PRIV_KEY;

BOOL SIMPLE_kull_m_crypto_hkey(HCRYPTPROV hProv, ALG_ID calgid, LPCVOID key, DWORD keyLen, DWORD flags, HCRYPTKEY *hKey);
BOOL SIMPLE_kull_m_file_readData(PCWCHAR fileName, PBYTE * data, PDWORD lenght);
BOOL SIMPLE_kull_m_file_writeData(PCWCHAR fileName, LPCVOID data, DWORD lenght);
void decryptFileWithKey(HCRYPTPROV hProv, HCRYPTKEY hUserRsaKey, int argc, wchar_t * argv[]);

int wmain(int argc, wchar_t * argv[])
{
HCRYPTPROV hProv;
HCRYPTKEY hRsaKey, hAesKey;
HCRYPTKEY hMalwareRsaKey, hUserRsaKey;
PBYTE pbRsaKey;
PWANA_FORMAT pbEncData;
DWORD cbRsaKey, cbEncData, cbRealDataLen, cryptoMode = CRYPT_MODE_CBC;
PWCHAR p;
DWORD cbRsaKey, cbData, i, dataLen;
PENC_PRIV_KEY pEnc;
PDEC_PRIV_KEY pDec;
PWSTR ext;

if(argc > 2)
{
wprintf(L"Using \'%s\' to decrypt \'%s\' file...\n\n", argv[1], argv[2]);
if(SIMPLE_kull_m_file_readData(argv[1], &pbRsaKey, &cbRsaKey))
if(CryptAcquireContext(&hProv, NULL, NULL, PROV_RSA_AES, CRYPT_VERIFYCONTEXT)) // we'll do RSA / AES stuff
{
if(SIMPLE_kull_m_file_readData(argv[2], (PBYTE *) &pbEncData, &cbEncData))
ext = PathFindExtension(argv[2]);
if(ext && (_wcsicmp(ext, L".eky") == 0))
{
if(p = wcsrchr(argv[2], L'.'))
wprintf(L"Malware PK: %s\nUser EncPK: %s\n", argv[1], argv[2]);
if(SIMPLE_kull_m_file_readData(argv[1], &pbRsaKey, &cbRsaKey))
{
*p = L'\0'; // 'delete' the WNCRY extension
if(pbEncData->magic == WANA_MAGIC)
if(CryptImportKey(hProv, pbRsaKey, cbRsaKey, 0, 0, &hMalwareRsaKey)) // let's import the malware PrivateKey - We all hope you have it :(
{
wprintf(L"Mode(?) : %u\nFilesize : %llu\n", pbEncData->unkOperation, pbEncData->qwDataSize);
if(CryptAcquireContext(&hProv, NULL, NULL, PROV_RSA_AES, CRYPT_VERIFYCONTEXT)) // we'll do RSA / AES stuff
if(SIMPLE_kull_m_file_readData(argv[2], (PBYTE *) &pEnc, &cbData))
{
if(CryptImportKey(hProv, pbRsaKey, cbRsaKey, 0, 0, &hRsaKey)) // let's import the user PrivateKey - I hope you have it :(
if((pEnc->totalBytes == RSA_ENC_SIZE) && (cbData == (pEnc->totalBytes + FIELD_OFFSET(ENC_PRIV_KEY, data))))
{
if(CryptDecrypt(hRsaKey, 0, TRUE, 0, pbEncData->key, &pbEncData->enc_keysize)) // decrypt the raw AES key from your RSA key
if(pDec = (PDEC_PRIV_KEY) LocalAlloc(LPTR, FIELD_OFFSET(DEC_PRIV_KEY, data) + pEnc->totalBytes)) // 0
{
if(SIMPLE_kull_m_crypto_hkey(hProv, CALG_AES_128, pbEncData->key, pbEncData->enc_keysize, 0, &hAesKey)) // let's make a AES 128 Windows key from raw bytes
for(i = 0; i < pEnc->totalBytes / RSA_2048_ENC; i++)
{
RtlCopyMemory(pDec->data + pDec->totalBytes, pEnc->data[i], RSA_2048_ENC);
dataLen = RSA_2048_ENC;
if(CryptDecrypt(hMalwareRsaKey, 0, TRUE, 0, pDec->data + pDec->totalBytes, &dataLen))
pDec->totalBytes += dataLen;
else wprintf(L"ERROR: CryptDecrypt(user - %u): %u\n", i, GetLastError());
}

switch(pDec->totalBytes)
{
case RSA_BAD_PAD:
wprintf(L"WARNING: user privatekey was encrypted with bad data at the end, fixed from %u to %u\n", RSA_BAD_PAD, RSA_DEC_SIZE);
pDec->totalBytes = RSA_DEC_SIZE;
break;
case RSA_DEC_SIZE:
wprintf(L"W00T: user privatekey good size ?\n");
break;
default:
wprintf(L"ERROR: Invalid user privatekey size: %u\n", pDec->totalBytes);
}

if(pDec->totalBytes == RSA_DEC_SIZE)
{
if(CryptSetKeyParam(hAesKey, KP_MODE, (PBYTE) &cryptoMode, 0)) // we'll do CBC
if(CryptImportKey(hProv, pDec->data, pDec->totalBytes, 0, 0, &hUserRsaKey))
{
cbRealDataLen = cbEncData - FIELD_OFFSET(WANA_FORMAT, data);
if(CryptDecrypt(hAesKey, 0, FALSE, 0, pbEncData->data, &cbRealDataLen)) // decrypt final data (padding issue, so 'FALSE' arg)
{
if(SIMPLE_kull_m_file_writeData(argv[2], pbEncData->data, (ULONG) pbEncData->qwDataSize))
wprintf(L"Final file: %s\n", argv[2]);
else wprintf(L"ERROR: writing final file \'%s\': %u\n", argv[2], GetLastError());
}
else wprintf(L"ERROR: CryptDecrypt: %u\n", GetLastError());
ext[1] = L'p';
wprintf(L"\nSave DecPK: %s\n", argv[2]);
if(!SIMPLE_kull_m_file_writeData(argv[2], pDec->data, pDec->totalBytes))
wprintf(L"ERROR: saving raw user privatekey file \'%s\': %u\n", argv[2], GetLastError());
decryptFileWithKey(hProv, hUserRsaKey, argc - 3, &argv[3]);
CryptDestroyKey(hUserRsaKey);
}
CryptDestroyKey(hAesKey);
else wprintf(L"ERROR: CryptImportKey(user): %u\n", GetLastError());
}
LocalFree(pDec);
}
else wprintf(L"ERROR: CryptDecrypt: %u\n", GetLastError());
CryptDestroyKey(hRsaKey);
}
else wprintf(L"ERROR: CryptImportKey: %u\n", GetLastError());
CryptReleaseContext(hProv, 0);
else wprintf(L"ERROR: abnormal encrypted size (H:%08x, D:%08x, N:%08x)\n", pEnc->totalBytes, cbData - FIELD_OFFSET(ENC_PRIV_KEY, data), RSA_ENC_SIZE);
LocalFree(pEnc);
}
else wprintf(L"ERROR: CryptAcquireContext: %u\n", GetLastError());
else wprintf(L"ERROR: reading user encrypted privatekey file \'%s\': %u\n", argv[2], GetLastError());
}
else wprintf(L"ERROR: CryptImportKey(malware): %u\n", GetLastError());
LocalFree(pbRsaKey);
}
else wprintf(L"ERROR: reading malware privatekey file \'%s\': %u\n", argv[1], GetLastError());
}
else
{
wprintf(L"Using raw user private key: \'%s\' to decrypt\n", argv[1]);
if(SIMPLE_kull_m_file_readData(argv[1], &pbRsaKey, &cbRsaKey))
{
if(CryptImportKey(hProv, pbRsaKey, cbRsaKey, 0, 0, &hUserRsaKey)) // let's import the user PrivateKey - I hope you have it :(
{
decryptFileWithKey(hProv, hUserRsaKey, argc - 2, &argv[2]);
CryptDestroyKey(hUserRsaKey);
}
else wprintf(L"ERROR: WANACRY! magic number not found\n");
else wprintf(L"ERROR: CryptImportKey: %u\n", GetLastError());
LocalFree(pbRsaKey);
}
else wprintf(L"ERROR: no \'.\' at the end of the user file ?\n");
LocalFree(pbEncData);
else wprintf(L"ERROR: reading user privatekey file \'%s\': %u\n", argv[1], GetLastError());
}
else wprintf(L"ERROR: reading userfile \'%s\': %u\n", argv[2], GetLastError());
LocalFree(pbRsaKey);
CryptReleaseContext(hProv, 0);
}
else wprintf(L"ERROR: reading privatekey file \'%s\': %u\n", argv[1], GetLastError());
else wprintf(L"ERROR: CryptAcquireContext: %u\n", GetLastError());
}
else wprintf(L"ERROR: program needs two arguments: <userprivatekey> <userfile.WNCRY>\n");
else wprintf(L"ERROR: program needs at least two arguments:\n %s <userprivatekey> <userfile.WNCRY> ...\n %s <malwareprivatekey> <encrypteduserprivatekey.eky> <userfile.WNCRY> ...\n", argv[0], argv[0]);
return 0;
}

void decryptFileWithKey(HCRYPTPROV hProv, HCRYPTKEY hUserRsaKey, int argc, wchar_t * argv[])
{
HCRYPTKEY hUserFileAesKey;
PWANA_FORMAT pbEncData;
PWCHAR p;
DWORD cbEncData, cbRealDataLen, cryptoMode = CRYPT_MODE_CBC;
int i;

for(i = 0; i < argc; i++)
{
wprintf(L"\nFilename : %s\n", argv[i]);
if(SIMPLE_kull_m_file_readData(argv[i], (PBYTE *) &pbEncData, &cbEncData))
{
if(p = wcsrchr(argv[i], L'.'))
{
*p = L'\0'; // 'delete' the WNCRY extension
if(pbEncData->magic == WANA_MAGIC)
{
wprintf(L"Mode(?) : %u\nFilesize : %llu\n", pbEncData->unkOperation, pbEncData->qwDataSize);
if(CryptDecrypt(hUserRsaKey, 0, TRUE, 0, pbEncData->key, &pbEncData->enc_keysize)) // decrypt the raw AES key from your RSA key
{
if(SIMPLE_kull_m_crypto_hkey(hProv, CALG_AES_128, pbEncData->key, pbEncData->enc_keysize, 0, &hUserFileAesKey)) // let's make a AES 128 Windows key from raw bytes
{
if(CryptSetKeyParam(hUserFileAesKey, KP_MODE, (PBYTE) &cryptoMode, 0)) // we'll do CBC
{
cbRealDataLen = cbEncData - FIELD_OFFSET(WANA_FORMAT, data);
if(CryptDecrypt(hUserFileAesKey, 0, FALSE, 0, pbEncData->data, &cbRealDataLen)) // decrypt final data (padding issue, so 'FALSE' arg)
{
if(SIMPLE_kull_m_file_writeData(argv[i], pbEncData->data, (ULONG) pbEncData->qwDataSize))
wprintf(L"Final file: %s\n", argv[i]);
else wprintf(L"ERROR: writing final file \'%s\': %u\n", argv[i], GetLastError());
}
else wprintf(L"ERROR: CryptDecrypt: %u\n", GetLastError());
}
CryptDestroyKey(hUserFileAesKey);
}
}
else wprintf(L"ERROR: CryptDecrypt: %u\n", GetLastError());
}
else wprintf(L"ERROR: WANACRY! magic number not found\n");
}
else wprintf(L"ERROR: no \'.\' at the end of the user file ?\n");
LocalFree(pbEncData);
}
else wprintf(L"ERROR: reading input file \'%s\': %u\n", argv[i], GetLastError());
}
}

BOOL SIMPLE_kull_m_crypto_hkey(HCRYPTPROV hProv, ALG_ID calgid, LPCVOID key, DWORD keyLen, DWORD flags, HCRYPTKEY *hKey)
{
BOOL status = FALSE;
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1 change: 1 addition & 0 deletions wanadecrypt.vcxproj
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Expand Up @@ -44,6 +44,7 @@
<GenerateDebugInformation>true</GenerateDebugInformation>
<EnableCOMDATFolding>true</EnableCOMDATFolding>
<OptimizeReferences>true</OptimizeReferences>
<AdditionalDependencies>shlwapi.lib;%(AdditionalDependencies)</AdditionalDependencies>
</Link>
</ItemDefinitionGroup>
<ItemGroup>
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