Windows: Fix vulnerability inherited from TrueCrypt that allows an attacker to detect with high probability if a hidden volume is present. Vulnerability reported by Ivanov Alexey Mikhailovich.

2024-11-10 13:13:34 +01:00 · 2016-08-08 00:49:00 +02:00 · 2016-08-08 00:49:00 +02:00 · 5b381ce7d7
commit 5b381ce7d7
parent 3fb2eedab8
5 changed files with 286 additions and 30 deletions
--- a/src/Common/Format.c
+++ b/src/Common/Format.c
@ -566,10 +566,63 @@ int TCFormatVolume (volatile FORMAT_VOL_PARAMETERS *volParams)
 	// Fill reserved header sectors (including the backup header area) with random data
 	if (!volParams->hiddenVol)
 	{
+		BOOL bUpdateBackup = FALSE;
+
 		nStatus = WriteRandomDataToReservedHeaderAreas (hwndDlg, dev, cryptoInfo, dataAreaSize, FALSE, FALSE);

 		if (nStatus != ERR_SUCCESS)
 			goto error;
+
+		// write fake hidden volume header to protect against attacks that use statistical entropy
+		// analysis to detect presence of hidden volumes.
+		
+		while (TRUE)
+		{
+			PCRYPTO_INFO dummyInfo = NULL;
+			LARGE_INTEGER hiddenOffset;
+
+			hiddenOffset.QuadPart = bUpdateBackup ? dataAreaSize + TC_VOLUME_HEADER_GROUP_SIZE + TC_HIDDEN_VOLUME_HEADER_OFFSET: TC_HIDDEN_VOLUME_HEADER_OFFSET;
+
+			nStatus = CreateVolumeHeaderInMemory (hwndDlg, FALSE,
+				header,
+				volParams->ea,
+				FIRST_MODE_OF_OPERATION_ID,
+				NULL,
+				0,
+				0,
+				NULL,
+				&dummyInfo,
+				dataAreaSize,
+				dataAreaSize,
+				dataOffset,
+				dataAreaSize,
+				0,
+				volParams->headerFlags,
+				FormatSectorSize,
+				FALSE);
+
+			if (nStatus != ERR_SUCCESS)
+				goto error;
+
+			crypto_close (dummyInfo);
+
+			if (!SetFilePointerEx ((HANDLE) dev, hiddenOffset, NULL, FILE_BEGIN))
+			{
+				nStatus = ERR_OS_ERROR;
+				goto error;
+			}
+
+			if (!WriteEffectiveVolumeHeader (volParams->bDevice, dev, header))
+			{
+				nStatus = ERR_OS_ERROR;
+				goto error;
+			}
+
+			if (bUpdateBackup)
+				break;
+
+			bUpdateBackup = TRUE;
+		}
 	}

 #ifndef DEBUG
--- a/src/Common/Password.c
+++ b/src/Common/Password.c
@ -437,9 +437,51 @@ int ChangePwd (const wchar_t *lpszVolume, Password *oldPassword, int old_pkcs5,
 				&& (cryptoInfo->HeaderFlags & TC_HEADER_FLAG_NONSYS_INPLACE_ENC) != 0
 				&& (cryptoInfo->HeaderFlags & ~TC_HEADER_FLAG_NONSYS_INPLACE_ENC) == 0)
 			{
+				PCRYPTO_INFO dummyInfo = NULL;
+				LARGE_INTEGER hiddenOffset;
+
 				nStatus = WriteRandomDataToReservedHeaderAreas (hwndDlg, dev, cryptoInfo, cryptoInfo->VolumeSize.Value, !backupHeader, backupHeader);
 				if (nStatus != ERR_SUCCESS)
 					goto error;
+
+				// write fake hidden volume header to protect against attacks that use statistical entropy
+				// analysis to detect presence of hidden volumes
+				hiddenOffset.QuadPart = backupHeader ? cryptoInfo->VolumeSize.Value + TC_VOLUME_HEADER_GROUP_SIZE + TC_HIDDEN_VOLUME_HEADER_OFFSET: TC_HIDDEN_VOLUME_HEADER_OFFSET;
+
+				nStatus = CreateVolumeHeaderInMemory (hwndDlg, FALSE,
+					buffer,
+					cryptoInfo->ea,
+					cryptoInfo->mode,
+					NULL,
+					0,
+					0,
+					NULL,
+					&dummyInfo,
+					cryptoInfo->VolumeSize.Value,
+					cryptoInfo->VolumeSize.Value,
+					cryptoInfo->EncryptedAreaStart.Value,
+					cryptoInfo->EncryptedAreaLength.Value,
+					truecryptMode? 0 : cryptoInfo->RequiredProgramVersion,
+					cryptoInfo->HeaderFlags,
+					cryptoInfo->SectorSize,
+					wipePass < wipePassCount - 1);
+
+				if (nStatus != ERR_SUCCESS)
+					goto error;
+
+				crypto_close (dummyInfo);
+
+				if (!SetFilePointerEx ((HANDLE) dev, hiddenOffset, NULL, FILE_BEGIN))
+				{
+					nStatus = ERR_OS_ERROR;
+					goto error;
+				}
+
+				if (!WriteEffectiveVolumeHeader (bDevice, dev, buffer))
+				{
+					nStatus = ERR_OS_ERROR;
+					goto error;
+				}
 			}

 			FlushFileBuffers (dev);
--- a/src/Common/Volumes.c
+++ b/src/Common/Volumes.c
@ -809,7 +809,7 @@ int CreateVolumeHeaderInMemory (HWND hwndDlg, BOOL bBoot, char *header, int ea,
 	unsigned char *p = (unsigned char *) header;
 	static CRYPTOPP_ALIGN_DATA(16) KEY_INFO keyInfo;

-	int nUserKeyLen = password->Length;
+	int nUserKeyLen = password? password->Length : 0;
 	PCRYPTO_INFO cryptoInfo = crypto_open ();
 	static char dk[MASTER_KEYDATA_SIZE];
 	int x;
@ -844,7 +844,10 @@ int CreateVolumeHeaderInMemory (HWND hwndDlg, BOOL bBoot, char *header, int ea,
 		}

 		if (!RandgetBytes (hwndDlg, keyInfo.master_keydata, bytesNeeded, TRUE))
+		{
+			crypto_close (cryptoInfo);
 			return ERR_CIPHER_INIT_WEAK_KEY;
+		}
 	}
 	else
 	{
@ -853,9 +856,17 @@ int CreateVolumeHeaderInMemory (HWND hwndDlg, BOOL bBoot, char *header, int ea,
 	}

 	// User key
-	memcpy (keyInfo.userKey, password->Text, nUserKeyLen);
-	keyInfo.keyLength = nUserKeyLen;
-	keyInfo.noIterations = get_pkcs5_iteration_count (pkcs5_prf, pim, FALSE, bBoot);
+	if (password)
+	{
+		memcpy (keyInfo.userKey, password->Text, nUserKeyLen);
+		keyInfo.keyLength = nUserKeyLen;
+		keyInfo.noIterations = get_pkcs5_iteration_count (pkcs5_prf, pim, FALSE, bBoot);
+	}
+	else
+	{
+		keyInfo.keyLength = 0;
+		keyInfo.noIterations = 0;
+	}

 	// User selected encryption algorithm
 	cryptoInfo->ea = ea;
@ -871,34 +882,51 @@ int CreateVolumeHeaderInMemory (HWND hwndDlg, BOOL bBoot, char *header, int ea,

 	// Salt for header key derivation
 	if (!RandgetBytes (hwndDlg, keyInfo.salt, PKCS5_SALT_SIZE, !bWipeMode))
-		return ERR_CIPHER_INIT_WEAK_KEY;
-
-	// PBKDF2 (PKCS5) is used to derive primary header key(s) and secondary header key(s) (XTS) from the password/keyfiles
-	switch (pkcs5_prf)
 	{
-	case SHA512:
-		derive_key_sha512 (keyInfo.userKey, keyInfo.keyLength, keyInfo.salt,
-			PKCS5_SALT_SIZE, keyInfo.noIterations, dk, GetMaxPkcs5OutSize());
-		break;
+		crypto_close (cryptoInfo);
+		return ERR_CIPHER_INIT_WEAK_KEY; 
+	}

-	case SHA256:
-		derive_key_sha256 (keyInfo.userKey, keyInfo.keyLength, keyInfo.salt,
-			PKCS5_SALT_SIZE, keyInfo.noIterations, dk, GetMaxPkcs5OutSize());
-		break;
+	if (password)
+	{
+		// PBKDF2 (PKCS5) is used to derive primary header key(s) and secondary header key(s) (XTS) from the password/keyfiles
+		switch (pkcs5_prf)
+		{
+		case SHA512:
+			derive_key_sha512 (keyInfo.userKey, keyInfo.keyLength, keyInfo.salt,
+				PKCS5_SALT_SIZE, keyInfo.noIterations, dk, GetMaxPkcs5OutSize());
+			break;

-	case RIPEMD160:
-		derive_key_ripemd160 (keyInfo.userKey, keyInfo.keyLength, keyInfo.salt,
-			PKCS5_SALT_SIZE, keyInfo.noIterations, dk, GetMaxPkcs5OutSize());
-		break;
+		case SHA256:
+			derive_key_sha256 (keyInfo.userKey, keyInfo.keyLength, keyInfo.salt,
+				PKCS5_SALT_SIZE, keyInfo.noIterations, dk, GetMaxPkcs5OutSize());
+			break;

-	case WHIRLPOOL:
-		derive_key_whirlpool (keyInfo.userKey, keyInfo.keyLength, keyInfo.salt,
-			PKCS5_SALT_SIZE, keyInfo.noIterations, dk, GetMaxPkcs5OutSize());
-		break;
+		case RIPEMD160:
+			derive_key_ripemd160 (keyInfo.userKey, keyInfo.keyLength, keyInfo.salt,
+				PKCS5_SALT_SIZE, keyInfo.noIterations, dk, GetMaxPkcs5OutSize());
+			break;

-	default:
-		// Unknown/wrong ID
-		TC_THROW_FATAL_EXCEPTION;
+		case WHIRLPOOL:
+			derive_key_whirlpool (keyInfo.userKey, keyInfo.keyLength, keyInfo.salt,
+				PKCS5_SALT_SIZE, keyInfo.noIterations, dk, GetMaxPkcs5OutSize());
+			break;
+
+
+		default:
+			// Unknown/wrong ID
+			crypto_close (cryptoInfo);
+			TC_THROW_FATAL_EXCEPTION;
+		}
+	}
+	else
+	{
+		// generate a random key
+		if (!RandgetBytes(hwndDlg, dk, GetMaxPkcs5OutSize(), !bWipeMode))
+		{
+			crypto_close (cryptoInfo);
+			return ERR_CIPHER_INIT_WEAK_KEY; 
+		}
 	}

 	/* Header setup */
@ -950,6 +978,7 @@ int CreateVolumeHeaderInMemory (HWND hwndDlg, BOOL bBoot, char *header, int ea,
 		|| sectorSize > TC_MAX_VOLUME_SECTOR_SIZE
 		|| sectorSize % ENCRYPTION_DATA_UNIT_SIZE != 0)
 	{
+		crypto_close (cryptoInfo);
 		TC_THROW_FATAL_EXCEPTION;
 	}

@ -978,11 +1007,17 @@ int CreateVolumeHeaderInMemory (HWND hwndDlg, BOOL bBoot, char *header, int ea,

 	retVal = EAInit (cryptoInfo->ea, dk + primaryKeyOffset, cryptoInfo->ks);
 	if (retVal != ERR_SUCCESS)
+	{
+		crypto_close (cryptoInfo);
 		return retVal;
+	}

 	// Mode of operation
 	if (!EAInitMode (cryptoInfo))
+	{
+		crypto_close (cryptoInfo);
 		return ERR_OUTOFMEMORY;
+	}


 	// Encrypt the entire header (except the salt)
@ -996,7 +1031,10 @@ int CreateVolumeHeaderInMemory (HWND hwndDlg, BOOL bBoot, char *header, int ea,
 	// Init with the master key(s)
 	retVal = EAInit (cryptoInfo->ea, keyInfo.master_keydata + primaryKeyOffset, cryptoInfo->ks);
 	if (retVal != ERR_SUCCESS)
+	{
+		crypto_close (cryptoInfo);
 		return retVal;
+	}

 	memcpy (cryptoInfo->master_keydata, keyInfo.master_keydata, MASTER_KEYDATA_SIZE);

@ -1010,7 +1048,10 @@ int CreateVolumeHeaderInMemory (HWND hwndDlg, BOOL bBoot, char *header, int ea,

 	// Mode of operation
 	if (!EAInitMode (cryptoInfo))
+	{
+		crypto_close (cryptoInfo);
 		return ERR_OUTOFMEMORY;
+	}


 #ifdef VOLFORMAT
--- a/src/ExpandVolume/ExpandVolume.c
+++ b/src/ExpandVolume/ExpandVolume.c
@ -804,7 +804,7 @@ static int ExpandVolume (HWND hwndDlg, wchar_t *lpszVolume, Password *pVolumePas
 			cryptoInfo->RequiredProgramVersion,
 			cryptoInfo->HeaderFlags,
 			cryptoInfo->SectorSize,
-			TRUE ); // use slow poll
+			FALSE ); // use slow poll

 		if (ci != NULL)
 			crypto_close (ci);
@ -818,8 +818,7 @@ static int ExpandVolume (HWND hwndDlg, wchar_t *lpszVolume, Password *pVolumePas
 			goto error;
 		}

-		nStatus = _lwrite ((HFILE) dev, buffer, TC_VOLUME_HEADER_EFFECTIVE_SIZE);
-		if (nStatus != TC_VOLUME_HEADER_EFFECTIVE_SIZE)
+		if (!WriteEffectiveVolumeHeader (bDevice, dev, buffer))
 		{
 			nStatus = ERR_OS_ERROR;
 			goto error;
@ -835,9 +834,51 @@ static int ExpandVolume (HWND hwndDlg, wchar_t *lpszVolume, Password *pVolumePas
 			)
 		{
 			//DebugAddProgressDlgStatus(hwndDlg, L"WriteRandomDataToReservedHeaderAreas() ...\r\n");
+			PCRYPTO_INFO dummyInfo = NULL;
+			LARGE_INTEGER hiddenOffset;
+
 			nStatus = WriteRandomDataToReservedHeaderAreas (hwndDlg, dev, cryptoInfo, newDataAreaSize, !backupHeader, backupHeader);
 			if (nStatus != ERR_SUCCESS)
 				goto error;
+
+			// write fake hidden volume header to protect against attacks that use statistical entropy
+			// analysis to detect presence of hidden volumes
+			hiddenOffset.QuadPart = headerOffset.QuadPart + TC_HIDDEN_VOLUME_HEADER_OFFSET;
+
+			nStatus = CreateVolumeHeaderInMemory (hwndDlg, FALSE,
+				buffer,
+				cryptoInfo->ea,
+				cryptoInfo->mode,
+				NULL,
+				0,
+				0,
+				NULL,
+				&dummyInfo,
+				newDataAreaSize,
+				newDataAreaSize, // hiddenVolumeSize
+				cryptoInfo->EncryptedAreaStart.Value,
+				newDataAreaSize,
+				cryptoInfo->RequiredProgramVersion,
+				cryptoInfo->HeaderFlags,
+				cryptoInfo->SectorSize,
+				FALSE ); // use slow poll
+
+			if (nStatus != ERR_SUCCESS)
+				goto error;
+
+			crypto_close (dummyInfo);
+
+			if (!SetFilePointerEx ((HANDLE) dev, hiddenOffset, NULL, FILE_BEGIN))
+			{
+				nStatus = ERR_OS_ERROR;
+				goto error;
+			}
+
+			if (!WriteEffectiveVolumeHeader (bDevice, dev, buffer))
+			{
+				nStatus = ERR_OS_ERROR;
+				goto error;
+			}
 		}

 		FlushFileBuffers (dev);
--- a/src/Format/InPlace.c
+++ b/src/Format/InPlace.c
@ -566,6 +566,8 @@ int EncryptPartitionInPlaceBegin (volatile FORMAT_VOL_PARAMETERS *volParams, vol
 	// Prepare the backup header
 	for (int wipePass = 0; wipePass < (wipeAlgorithm == TC_WIPE_NONE ? 1 : PRAND_HEADER_WIPE_PASSES); wipePass++)
 	{
+		PCRYPTO_INFO dummyInfo = NULL;
+
 		nStatus = CreateVolumeHeaderInMemory (hwndDlg, FALSE,
 			header,
 			volParams->ea,
@ -607,6 +609,47 @@ int EncryptPartitionInPlaceBegin (volatile FORMAT_VOL_PARAMETERS *volParams, vol

 		if (nStatus != ERR_SUCCESS)
 			goto closing_seq;
+
+		// write fake hidden volume header to protect against attacks that use statistical entropy
+		// analysis to detect presence of hidden volumes
+		nStatus = CreateVolumeHeaderInMemory (hwndDlg, FALSE,
+			header,
+			volParams->ea,
+			FIRST_MODE_OF_OPERATION_ID,
+			NULL,
+			0,
+			0,
+			NULL,
+			&dummyInfo,
+			dataAreaSize,
+			dataAreaSize,
+			TC_VOLUME_DATA_OFFSET + dataAreaSize,	// Start of the encrypted area = the first byte of the backup heeader (encrypting from the end)
+			dataAreaSize,	// No data is encrypted yet
+			0,
+			volParams->headerFlags | TC_HEADER_FLAG_NONSYS_INPLACE_ENC,
+			volParams->sectorSize,
+			wipeAlgorithm == TC_WIPE_NONE ? FALSE : (wipePass < PRAND_HEADER_WIPE_PASSES - 1));
+
+		if (nStatus != ERR_SUCCESS)
+			goto closing_seq;
+
+		crypto_close (dummyInfo);
+
+		offset.QuadPart += TC_HIDDEN_VOLUME_HEADER_OFFSET;
+
+		if (!SetFilePointerEx (dev, offset, NULL, FILE_BEGIN))
+		{
+			nStatus = ERR_OS_ERROR;
+			goto closing_seq;
+		}
+
+		// Write the fake hidden backup header to the partition
+		if (!WriteEffectiveVolumeHeader (TRUE, dev, (byte *) header))
+		{
+			nStatus = ERR_OS_ERROR;
+			goto closing_seq;
+		}
+
 	}


@ -1045,6 +1088,8 @@ int EncryptPartitionInPlaceResume (HANDLE dev,

 		for (int wipePass = 0; wipePass < (wipeAlgorithm == TC_WIPE_NONE ? 1 : PRAND_HEADER_WIPE_PASSES); wipePass++)
 		{
+			PCRYPTO_INFO dummyInfo = NULL;
+
 			nStatus = CreateVolumeHeaderInMemory (hwndDlg, FALSE,
 				header,
 				headerCryptoInfo->ea,
@ -1081,6 +1126,40 @@ int EncryptPartitionInPlaceResume (HANDLE dev,

 			if (nStatus != ERR_SUCCESS)
 				goto closing_seq;
+
+			// write fake hidden volume header to protect against attacks that use statistical entropy
+			// analysis to detect presence of hidden volumes
+			nStatus = CreateVolumeHeaderInMemory (hwndDlg, FALSE,
+				header,
+				headerCryptoInfo->ea,
+				headerCryptoInfo->mode,
+				NULL,
+				0,
+				0,
+				NULL,
+				&dummyInfo,
+				masterCryptoInfo->VolumeSize.Value,
+				masterCryptoInfo->VolumeSize.Value,
+				masterCryptoInfo->EncryptedAreaStart.Value,
+				masterCryptoInfo->EncryptedAreaLength.Value,
+				masterCryptoInfo->RequiredProgramVersion,
+				masterCryptoInfo->HeaderFlags | TC_HEADER_FLAG_NONSYS_INPLACE_ENC,
+				masterCryptoInfo->SectorSize,
+				wipeAlgorithm == TC_WIPE_NONE ? FALSE : (wipePass < PRAND_HEADER_WIPE_PASSES - 1));
+
+			if (nStatus != ERR_SUCCESS)
+				goto closing_seq;
+
+			crypto_close (dummyInfo);
+
+			offset.QuadPart += TC_HIDDEN_VOLUME_HEADER_OFFSET;
+
+			if (SetFilePointerEx (dev, offset, NULL, FILE_BEGIN) == 0
+				|| !WriteEffectiveVolumeHeader (TRUE, dev, (byte *) header))
+			{
+				nStatus = ERR_OS_ERROR;
+				goto closing_seq;
+			}
 		}

 		// Update the configuration files