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rufus/src/pki.c
Pete Batard f26fd2fbe3
[fido] add additional Authenticode validation before running the script 
* This basically means that the script is validate *TWICE*, using two
  completely independent signatures, before it is allowed to run, which
  should add another mitigation layer against TOCTOU (which we already
  friggin' mitigated against anyway) and other potential vectors of
  attack.
* Also remove -DisableFirstRunCustomize option and the associated cookie
  prompt monitoring, which the latest version of Fido no longer requires.
* Also update WDK version for signtool and flesh out PKI error messages.
2021-05-27 00:19:25 +01:00

747 lines
28 KiB
C
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/*
* Rufus: The Reliable USB Formatting Utility
* PKI functions (code signing, etc.)
* Copyright © 2015-2016 Pete Batard <pete@akeo.ie>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/* Memory leaks detection - define _CRTDBG_MAP_ALLOC as preprocessor macro */
#ifdef _CRTDBG_MAP_ALLOC
#include <stdlib.h>
#include <crtdbg.h>
#endif
#include <windows.h>
#include <stdio.h>
#include <wincrypt.h>
#include <wintrust.h>
#include <assert.h>
#include "rufus.h"
#include "resource.h"
#include "msapi_utf8.h"
#include "localization.h"
#define ENCODING (X509_ASN_ENCODING | PKCS_7_ASN_ENCODING)
// MinGW doesn't seem to have this one
#if !defined(szOID_NESTED_SIGNATURE)
#define szOID_NESTED_SIGNATURE "1.3.6.1.4.1.311.2.4.1"
#endif
// Signatures names we accept. Must be the the exact name, including capitalization,
// that CertGetNameStringA(CERT_NAME_ATTR_TYPE, szOID_COMMON_NAME) returns.
const char* cert_name[3] = { "Akeo Consulting", "Akeo Systems", "Pete Batard" };
// For added security, we also validate the country code of the certificate recipient.
const char* cert_country = "IE";
typedef struct {
LPWSTR lpszProgramName;
LPWSTR lpszPublisherLink;
LPWSTR lpszMoreInfoLink;
} SPROG_PUBLISHERINFO, *PSPROG_PUBLISHERINFO;
// https://msdn.microsoft.com/en-us/library/ee442238.aspx
typedef struct {
BLOBHEADER BlobHeader;
RSAPUBKEY RsaHeader;
BYTE Modulus[256]; // 2048 bit modulus
} RSA_2048_PUBKEY;
// The RSA public key modulus for the private key we use to sign the files on the server.
// NOTE 1: This openssl modulus must be *REVERSED* to be usable with Microsoft APIs
// NOTE 2: Also, this modulus is 2052 bits, and not 2048, because openssl adds an extra
// 0x00 at the beginning to force an integer sign. These extra 8 bits *MUST* be removed.
static uint8_t rsa_pubkey_modulus[] = {
/*
$ openssl genrsa -aes256 -out private.pem 2048
$ openssl rsa -in private.pem -pubout -out public.pem
$ openssl rsa -pubin -inform PEM -text -noout < public.pem
Public-Key: (2048 bit)
Modulus:
00:b6:40:7d:d1:98:7b:81:9e:be:23:0f:32:5d:55:
60:c6:bf:b4:41:bb:43:1b:f1:e1:e6:f9:2b:d6:dd:
11:50:e8:b9:3f:19:97:5e:a7:8b:4a:30:c6:76:58:
72:1c:ac:ff:a1:f8:96:6c:51:5d:13:11:e3:5b:11:
82:f5:9a:69:e4:28:97:0f:ca:1f:02:ea:1f:7d:dc:
f9:fc:79:2f:61:ff:8e:45:60:65:ba:37:9b:de:49:
05:6a:a8:fd:70:d0:0c:79:b6:d7:81:aa:54:c3:c6:
4a:87:a0:45:ee:ca:d5:d5:c5:c2:ac:86:42:b3:58:
27:d2:43:b9:37:f2:e6:75:66:17:53:d0:38:d0:c6:
57:c2:55:36:a2:43:87:ea:24:f0:96:ec:34:dd:79:
4d:80:54:9d:84:81:a7:cf:0c:a5:7c:d6:63:fa:7a:
66:30:a9:50:ee:f0:e5:f8:a2:2d:ac:fc:24:21:fe:
ef:e8:d3:6f:0e:27:b0:64:22:95:3e:6d:a6:66:97:
c6:98:c2:47:b3:98:69:4d:b1:b5:d3:6f:43:f5:d7:
a5:13:5e:8c:28:4f:62:4e:01:48:0a:63:89:e7:ca:
34:aa:7d:2f:bb:70:e0:31:bb:39:49:a3:d2:c9:2e:
a6:30:54:9a:5c:4d:58:17:d9:fc:3a:43:e6:8e:2a:
18:e9
Exponent: 65537 (0x10001)
*/
0x00, 0xb6, 0x40, 0x7d, 0xd1, 0x98, 0x7b, 0x81, 0x9e, 0xbe, 0x23, 0x0f, 0x32, 0x5d, 0x55,
0x60, 0xc6, 0xbf, 0xb4, 0x41, 0xbb, 0x43, 0x1b, 0xf1, 0xe1, 0xe6, 0xf9, 0x2b, 0xd6, 0xdd,
0x11, 0x50, 0xe8, 0xb9, 0x3f, 0x19, 0x97, 0x5e, 0xa7, 0x8b, 0x4a, 0x30, 0xc6, 0x76, 0x58,
0x72, 0x1c, 0xac, 0xff, 0xa1, 0xf8, 0x96, 0x6c, 0x51, 0x5d, 0x13, 0x11, 0xe3, 0x5b, 0x11,
0x82, 0xf5, 0x9a, 0x69, 0xe4, 0x28, 0x97, 0x0f, 0xca, 0x1f, 0x02, 0xea, 0x1f, 0x7d, 0xdc,
0xf9, 0xfc, 0x79, 0x2f, 0x61, 0xff, 0x8e, 0x45, 0x60, 0x65, 0xba, 0x37, 0x9b, 0xde, 0x49,
0x05, 0x6a, 0xa8, 0xfd, 0x70, 0xd0, 0x0c, 0x79, 0xb6, 0xd7, 0x81, 0xaa, 0x54, 0xc3, 0xc6,
0x4a, 0x87, 0xa0, 0x45, 0xee, 0xca, 0xd5, 0xd5, 0xc5, 0xc2, 0xac, 0x86, 0x42, 0xb3, 0x58,
0x27, 0xd2, 0x43, 0xb9, 0x37, 0xf2, 0xe6, 0x75, 0x66, 0x17, 0x53, 0xd0, 0x38, 0xd0, 0xc6,
0x57, 0xc2, 0x55, 0x36, 0xa2, 0x43, 0x87, 0xea, 0x24, 0xf0, 0x96, 0xec, 0x34, 0xdd, 0x79,
0x4d, 0x80, 0x54, 0x9d, 0x84, 0x81, 0xa7, 0xcf, 0x0c, 0xa5, 0x7c, 0xd6, 0x63, 0xfa, 0x7a,
0x66, 0x30, 0xa9, 0x50, 0xee, 0xf0, 0xe5, 0xf8, 0xa2, 0x2d, 0xac, 0xfc, 0x24, 0x21, 0xfe,
0xef, 0xe8, 0xd3, 0x6f, 0x0e, 0x27, 0xb0, 0x64, 0x22, 0x95, 0x3e, 0x6d, 0xa6, 0x66, 0x97,
0xc6, 0x98, 0xc2, 0x47, 0xb3, 0x98, 0x69, 0x4d, 0xb1, 0xb5, 0xd3, 0x6f, 0x43, 0xf5, 0xd7,
0xa5, 0x13, 0x5e, 0x8c, 0x28, 0x4f, 0x62, 0x4e, 0x01, 0x48, 0x0a, 0x63, 0x89, 0xe7, 0xca,
0x34, 0xaa, 0x7d, 0x2f, 0xbb, 0x70, 0xe0, 0x31, 0xbb, 0x39, 0x49, 0xa3, 0xd2, 0xc9, 0x2e,
0xa6, 0x30, 0x54, 0x9a, 0x5c, 0x4d, 0x58, 0x17, 0xd9, 0xfc, 0x3a, 0x43, 0xe6, 0x8e, 0x2a,
0x18, 0xe9
};
/*
* FormatMessage does not handle PKI errors
*/
const char* WinPKIErrorString(void)
{
static char error_string[64];
DWORD error_code = GetLastError();
if (((error_code >> 16) != 0x8009) && ((error_code >> 16) != 0x800B))
return WindowsErrorString();
switch (error_code) {
// See also https://docs.microsoft.com/en-gb/windows/desktop/com/com-error-codes-4
case NTE_BAD_UID:
return "Bad UID.";
case NTE_NO_KEY:
return "Key does not exist.";
case NTE_BAD_KEYSET:
return "Keyset does not exist.";
case NTE_BAD_ALGID:
return "Invalid algorithm specified.";
case NTE_BAD_VER:
return "Bad version of provider.";
case NTE_BAD_SIGNATURE:
return "Invalid Signature.";
case CRYPT_E_MSG_ERROR:
return "An error occurred while performing an operation on a cryptographic message.";
case CRYPT_E_UNKNOWN_ALGO:
return "Unknown cryptographic algorithm.";
case CRYPT_E_INVALID_MSG_TYPE:
return "Invalid cryptographic message type.";
case CRYPT_E_HASH_VALUE:
return "The hash value is not correct";
case CRYPT_E_ISSUER_SERIALNUMBER:
return "Invalid issuer and/or serial number.";
case CRYPT_E_BAD_LEN:
return "The length specified for the output data was insufficient.";
case CRYPT_E_BAD_ENCODE:
return "An error occurred during encode or decode operation.";
case CRYPT_E_FILE_ERROR:
return "An error occurred while reading or writing to a file.";
case CRYPT_E_NOT_FOUND:
return "Cannot find object or property.";
case CRYPT_E_EXISTS:
return "The object or property already exists.";
case CRYPT_E_NO_PROVIDER:
return "No provider was specified for the store or object.";
case CRYPT_E_DELETED_PREV:
return "The previous certificate or CRL context was deleted.";
case CRYPT_E_NO_MATCH:
return "Cannot find the requested object.";
case CRYPT_E_UNEXPECTED_MSG_TYPE:
case CRYPT_E_NO_KEY_PROPERTY:
case CRYPT_E_NO_DECRYPT_CERT:
return "Private key or certificate issue";
case CRYPT_E_BAD_MSG:
return "Not a cryptographic message.";
case CRYPT_E_NO_SIGNER:
return "The signed cryptographic message does not have a signer for the specified signer index.";
case CRYPT_E_REVOKED:
return "The certificate is revoked.";
case CRYPT_E_NO_REVOCATION_DLL:
case CRYPT_E_NO_REVOCATION_CHECK:
case CRYPT_E_REVOCATION_OFFLINE:
case CRYPT_E_NOT_IN_REVOCATION_DATABASE:
return "Cannot check certificate revocation.";
case CRYPT_E_INVALID_NUMERIC_STRING:
case CRYPT_E_INVALID_PRINTABLE_STRING:
case CRYPT_E_INVALID_IA5_STRING:
case CRYPT_E_INVALID_X500_STRING:
case CRYPT_E_NOT_CHAR_STRING:
return "Invalid string.";
case CRYPT_E_SECURITY_SETTINGS:
return "The cryptographic operation failed due to a local security option setting.";
case CRYPT_E_NO_VERIFY_USAGE_CHECK:
case CRYPT_E_VERIFY_USAGE_OFFLINE:
return "Cannot complete usage check.";
case CRYPT_E_NO_TRUSTED_SIGNER:
return "None of the signers of the cryptographic message or certificate trust list is trusted.";
case CERT_E_UNTRUSTEDROOT:
return "The root certificate is not trusted.";
case TRUST_E_SYSTEM_ERROR:
return "A system-level error occurred while verifying trust.";
case TRUST_E_NO_SIGNER_CERT:
return "The certificate for the signer of the message is invalid or not found.";
case TRUST_E_COUNTER_SIGNER:
return "One of the counter signatures was invalid.";
case TRUST_E_CERT_SIGNATURE:
return "The signature of the certificate cannot be verified.";
case TRUST_E_TIME_STAMP:
return "The timestamp could not be verified.";
case TRUST_E_BAD_DIGEST:
return "The file content has been altered.";
case TRUST_E_BASIC_CONSTRAINTS:
return "A certificate's basic constraint extension has not been observed.";
case TRUST_E_NOSIGNATURE:
return "Not digitally signed.";
case TRUST_E_EXPLICIT_DISTRUST:
return "One of the certificates used was marked as untrusted by the user.";
default:
static_sprintf(error_string, "Unknown PKI error 0x%08lX", error_code);
return error_string;
}
}
// Mostly from https://support.microsoft.com/en-us/kb/323809
char* GetSignatureName(const char* path, const char* country_code, BOOL bSilent)
{
static char szSubjectName[128];
char szCountry[3] = "__";
char *p = NULL, *mpath = NULL;
int i;
BOOL r;
HCERTSTORE hStore = NULL;
HCRYPTMSG hMsg = NULL;
PCCERT_CONTEXT pCertContext = NULL;
DWORD dwSize, dwEncoding, dwContentType, dwFormatType;
PCMSG_SIGNER_INFO pSignerInfo = NULL;
DWORD dwSignerInfo = 0;
CERT_INFO CertInfo = { 0 };
SPROG_PUBLISHERINFO ProgPubInfo = { 0 };
wchar_t *szFileName;
// If the path is NULL, get the signature of the current runtime
if (path == NULL) {
szFileName = calloc(MAX_PATH, sizeof(wchar_t));
if (szFileName == NULL)
return NULL;
dwSize = GetModuleFileNameW(NULL, szFileName, MAX_PATH);
if ((dwSize == 0) || ((dwSize == MAX_PATH) && (GetLastError() == ERROR_INSUFFICIENT_BUFFER))) {
uprintf("PKI: Could not get module filename: %s", WinPKIErrorString());
goto out;
}
mpath = wchar_to_utf8(szFileName);
} else {
szFileName = utf8_to_wchar(path);
}
// Get message handle and store handle from the signed file.
for (i = 0; i < 5; i++) {
r = CryptQueryObject(CERT_QUERY_OBJECT_FILE, szFileName,
CERT_QUERY_CONTENT_FLAG_PKCS7_SIGNED_EMBED, CERT_QUERY_FORMAT_FLAG_BINARY,
0, &dwEncoding, &dwContentType, &dwFormatType, &hStore, &hMsg, NULL);
if (r)
break;
if (i == 0)
uprintf("PKI: Failed to get signature for '%s': %s", (path==NULL)?mpath:path, WinPKIErrorString());
if (path == NULL)
break;
uprintf("PKI: Retrying...");
Sleep(2000);
}
if (!r)
goto out;
// Get signer information size.
r = CryptMsgGetParam(hMsg, CMSG_SIGNER_INFO_PARAM, 0, NULL, &dwSignerInfo);
if (!r) {
uprintf("PKI: Failed to get signer size: %s", WinPKIErrorString());
goto out;
}
// Allocate memory for signer information.
pSignerInfo = (PCMSG_SIGNER_INFO)calloc(dwSignerInfo, 1);
if (!pSignerInfo) {
uprintf("PKI: Could not allocate memory for signer information");
goto out;
}
// Get Signer Information.
r = CryptMsgGetParam(hMsg, CMSG_SIGNER_INFO_PARAM, 0, (PVOID)pSignerInfo, &dwSignerInfo);
if (!r) {
uprintf("PKI: Failed to get signer information: %s", WinPKIErrorString());
goto out;
}
// Search for the signer certificate in the temporary certificate store.
CertInfo.Issuer = pSignerInfo->Issuer;
CertInfo.SerialNumber = pSignerInfo->SerialNumber;
pCertContext = CertFindCertificateInStore(hStore, ENCODING, 0, CERT_FIND_SUBJECT_CERT, (PVOID)&CertInfo, NULL);
if (!pCertContext) {
uprintf("PKI: Failed to locate signer certificate in temporary store: %s", WinPKIErrorString());
goto out;
}
// If a country code is provided, validate that the certificate we have is for the same country
if (country_code != NULL) {
dwSize = CertGetNameStringA(pCertContext, CERT_NAME_ATTR_TYPE, 0, szOID_COUNTRY_NAME,
szCountry, sizeof(szCountry));
if (dwSize < 2) {
uprintf("PKI: Failed to get Country Code");
goto out;
}
if (strcmpi(country_code, szCountry) != 0) {
uprintf("PKI: Unexpected Country Code (Found '%s', expected '%s')", szCountry, country_code);
goto out;
}
}
// Isolate the signing certificate subject name
dwSize = CertGetNameStringA(pCertContext, CERT_NAME_ATTR_TYPE, 0, szOID_COMMON_NAME,
szSubjectName, sizeof(szSubjectName));
if (dwSize <= 1) {
uprintf("PKI: Failed to get Subject Name");
goto out;
}
if (szCountry[0] == '_')
suprintf("Binary executable is signed by '%s'", szSubjectName);
else
suprintf("Binary executable is signed by '%s' (%s)", szSubjectName, szCountry);
p = szSubjectName;
out:
safe_free(mpath);
safe_free(szFileName);
safe_free(ProgPubInfo.lpszProgramName);
safe_free(ProgPubInfo.lpszPublisherLink);
safe_free(ProgPubInfo.lpszMoreInfoLink);
safe_free(pSignerInfo);
if (pCertContext != NULL)
CertFreeCertificateContext(pCertContext);
if (hStore != NULL)
CertCloseStore(hStore, 0);
if (hMsg != NULL)
CryptMsgClose(hMsg);
return p;
}
// The timestamping authorities we use are RFC 3161 compliant
static uint64_t GetRFC3161TimeStamp(PCMSG_SIGNER_INFO pSignerInfo)
{
BOOL r, found = FALSE;
DWORD n, dwSize = 0;
PCRYPT_CONTENT_INFO pCounterSignerInfo = NULL;
uint64_t ts = 0ULL;
uint8_t *timestamp_token;
size_t timestamp_token_size;
char* timestamp_str;
size_t timestamp_str_size;
// Loop through unauthenticated attributes for szOID_RFC3161_counterSign OID
for (n = 0; n < pSignerInfo->UnauthAttrs.cAttr; n++) {
if (lstrcmpA(pSignerInfo->UnauthAttrs.rgAttr[n].pszObjId, szOID_RFC3161_counterSign) == 0) {
// Depending on how Microsoft implemented their timestamp checks, and the fact that we are dealing
// with UnauthAttrs, there's a possibility that an attacker may add a "fake" RFC 3161 countersigner
// to try to trick us into using their timestamp data. Detect that.
if (found) {
uprintf("PKI: Multiple RFC 3161 countersigners found. This could indicate something very nasty...");
return 0ULL;
}
found = TRUE;
// Read the countersigner message data
r = CryptDecodeObjectEx(PKCS_7_ASN_ENCODING, PKCS_CONTENT_INFO,
pSignerInfo->UnauthAttrs.rgAttr[n].rgValue[0].pbData,
pSignerInfo->UnauthAttrs.rgAttr[n].rgValue[0].cbData,
CRYPT_DECODE_ALLOC_FLAG, NULL, (PVOID)&pCounterSignerInfo, &dwSize);
if (!r) {
uprintf("PKI: Could not retrieve RFC 3161 countersigner data: %s", WinPKIErrorString());
continue;
}
// Get the RFC 3161 timestamp message
timestamp_token = get_data_from_asn1(pCounterSignerInfo->Content.pbData,
pCounterSignerInfo->Content.cbData, szOID_TIMESTAMP_TOKEN,
// 0x04 = "Octet String" ASN.1 tag
0x04, &timestamp_token_size);
if (timestamp_token) {
timestamp_str = get_data_from_asn1(timestamp_token, timestamp_token_size, NULL,
// 0x18 = "Generalized Time" ASN.1 tag
0x18, &timestamp_str_size);
if (timestamp_str) {
// As per RFC 3161 The syntax is: YYYYMMDDhhmmss[.s...]Z
if ((timestamp_str_size < 14) || (timestamp_str[timestamp_str_size - 1] != 'Z')) {
// Sanity checks
uprintf("PKI: Not an RFC 3161 timestamp");
DumpBufferHex(timestamp_str, timestamp_str_size);
} else {
ts = strtoull(timestamp_str, NULL, 10);
}
}
}
LocalFree(pCounterSignerInfo);
}
}
return ts;
}
// The following is used to get the RFP 3161 timestamp of a nested signature
static uint64_t GetNestedRFC3161TimeStamp(PCMSG_SIGNER_INFO pSignerInfo)
{
BOOL r, found = FALSE;
DWORD n, dwSize = 0;
PCRYPT_CONTENT_INFO pNestedSignature = NULL;
PCMSG_SIGNER_INFO pNestedSignerInfo = NULL;
HCRYPTMSG hMsg = NULL;
uint64_t ts = 0ULL;
// Loop through unauthenticated attributes for szOID_NESTED_SIGNATURE OID
for (n = 0; ; n++) {
if (pNestedSignature != NULL) {
LocalFree(pNestedSignature);
pNestedSignature = NULL;
}
if (hMsg != NULL) {
CryptMsgClose(hMsg);
hMsg = NULL;
}
safe_free(pNestedSignerInfo);
if (n >= pSignerInfo->UnauthAttrs.cAttr)
break;
if (lstrcmpA(pSignerInfo->UnauthAttrs.rgAttr[n].pszObjId, szOID_NESTED_SIGNATURE) == 0) {
if (found) {
uprintf("PKI: Multiple nested signatures found. This could indicate something very nasty...");
return 0ULL;
}
found = TRUE;
r = CryptDecodeObjectEx(PKCS_7_ASN_ENCODING, PKCS_CONTENT_INFO,
pSignerInfo->UnauthAttrs.rgAttr[n].rgValue[0].pbData,
pSignerInfo->UnauthAttrs.rgAttr[n].rgValue[0].cbData,
CRYPT_DECODE_ALLOC_FLAG, NULL, (PVOID)&pNestedSignature, &dwSize);
if (!r) {
uprintf("PKI: Could not retrieve nested signature data: %s", WinPKIErrorString());
continue;
}
hMsg = CryptMsgOpenToDecode(ENCODING, CMSG_DETACHED_FLAG, CMSG_SIGNED, (HCRYPTPROV)NULL, NULL, NULL);
if (hMsg == NULL) {
uprintf("PKI: Could not create nested signature message: %s", WinPKIErrorString());
continue;
}
r = CryptMsgUpdate(hMsg, pNestedSignature->Content.pbData, pNestedSignature->Content.cbData, TRUE);
if (!r) {
uprintf("PKI: Could not update message: %s", WinPKIErrorString());
continue;
}
// Get nested signer
r = CryptMsgGetParam(hMsg, CMSG_SIGNER_INFO_PARAM, 0, NULL, &dwSize);
if (!r) {
uprintf("PKI: Failed to get nested signer size: %s", WinPKIErrorString());
continue;
}
pNestedSignerInfo = (PCMSG_SIGNER_INFO)calloc(dwSize, 1);
if (!pNestedSignerInfo) {
uprintf("PKI: Could not allocate memory for nested signer");
continue;
}
r = CryptMsgGetParam(hMsg, CMSG_SIGNER_INFO_PARAM, 0, (PVOID)pNestedSignerInfo, &dwSize);
if (!r) {
uprintf("PKI: Failed to get nested signer information: %s", WinPKIErrorString());
continue;
}
ts = GetRFC3161TimeStamp(pNestedSignerInfo);
}
}
return ts;
}
// Return the signature timestamp (as a YYYYMMDDHHMMSS value) or 0 on error
uint64_t GetSignatureTimeStamp(const char* path)
{
char *mpath = NULL;
BOOL r;
HMODULE hm;
HCERTSTORE hStore = NULL;
HCRYPTMSG hMsg = NULL;
DWORD dwSize, dwEncoding, dwContentType, dwFormatType;
PCMSG_SIGNER_INFO pSignerInfo = NULL;
DWORD dwSignerInfo = 0;
wchar_t *szFileName;
uint64_t timestamp = 0ULL, nested_timestamp;
// If the path is NULL, get the signature of the current runtime
if (path == NULL) {
szFileName = calloc(MAX_PATH, sizeof(wchar_t));
if (szFileName == NULL)
goto out;
hm = GetModuleHandle(NULL);
if (hm == NULL) {
uprintf("PKI: Could not get current executable handle: %s", WinPKIErrorString());
goto out;
}
dwSize = GetModuleFileNameW(hm, szFileName, MAX_PATH);
if ((dwSize == 0) || ((dwSize == MAX_PATH) && (GetLastError() == ERROR_INSUFFICIENT_BUFFER))) {
uprintf("PKI: Could not get module filename: %s", WinPKIErrorString());
goto out;
}
mpath = wchar_to_utf8(szFileName);
} else {
szFileName = utf8_to_wchar(path);
}
// Get message handle and store handle from the signed file.
r = CryptQueryObject(CERT_QUERY_OBJECT_FILE, szFileName,
CERT_QUERY_CONTENT_FLAG_PKCS7_SIGNED_EMBED, CERT_QUERY_FORMAT_FLAG_BINARY,
0, &dwEncoding, &dwContentType, &dwFormatType, &hStore, &hMsg, NULL);
if (!r) {
uprintf("PKI: Failed to get signature for '%s': %s", (path==NULL)?mpath:path, WinPKIErrorString());
goto out;
}
// Get signer information size.
r = CryptMsgGetParam(hMsg, CMSG_SIGNER_INFO_PARAM, 0, NULL, &dwSignerInfo);
if (!r) {
uprintf("PKI: Failed to get signer size: %s", WinPKIErrorString());
goto out;
}
// Allocate memory for signer information.
pSignerInfo = (PCMSG_SIGNER_INFO)calloc(dwSignerInfo, 1);
if (!pSignerInfo) {
uprintf("PKI: Could not allocate memory for signer information");
goto out;
}
// Get Signer Information.
r = CryptMsgGetParam(hMsg, CMSG_SIGNER_INFO_PARAM, 0, (PVOID)pSignerInfo, &dwSignerInfo);
if (!r) {
uprintf("PKI: Failed to get signer information: %s", WinPKIErrorString());
goto out;
}
// Get the RFC 3161 timestamp
timestamp = GetRFC3161TimeStamp(pSignerInfo);
if (timestamp)
uprintf("Note: '%s' has timestamp %s", (path==NULL)?mpath:path, TimestampToHumanReadable(timestamp));
// Because we are currently using both SHA-1 and SHA-256 signatures, we are in the very specific
// situation that Windows may say our executable passes Authenticode validation on Windows 7 or
// later (which includes timestamp validation) even if the SHA-1 signature or timestamps have
// been altered.
// This means that, if we don't also check the nested SHA-256 signature timestamp, an attacker
// could alter the SHA-1 one (which is the one we use by default for chronology validation) and
// trick us into using an invalid timestamp value. To prevent this, we validate that, if we have
// both a regular and nested timestamp, they are within 60 seconds of each other.
nested_timestamp = GetNestedRFC3161TimeStamp(pSignerInfo);
if (nested_timestamp)
uprintf("Note: '%s' has nested timestamp %s", (path==NULL)?mpath:path, TimestampToHumanReadable(nested_timestamp));
if ((timestamp != 0ULL) && (nested_timestamp != 0ULL)) {
if (_abs64(nested_timestamp - timestamp) > 100) {
uprintf("PKI: Signature timestamp and nested timestamp differ by more than a minute. "
"This could indicate something very nasty...", timestamp, nested_timestamp);
timestamp = 0ULL;
}
}
out:
safe_free(mpath);
safe_free(szFileName);
safe_free(pSignerInfo);
if (hStore != NULL)
CertCloseStore(hStore, 0);
if (hMsg != NULL)
CryptMsgClose(hMsg);
return timestamp;
}
// From https://msdn.microsoft.com/en-us/library/windows/desktop/aa382384.aspx
LONG ValidateSignature(HWND hDlg, const char* path)
{
LONG r;
WINTRUST_DATA trust_data = { 0 };
WINTRUST_FILE_INFO trust_file = { 0 };
GUID guid_generic_verify = // WINTRUST_ACTION_GENERIC_VERIFY_V2
{ 0xaac56b, 0xcd44, 0x11d0,{ 0x8c, 0xc2, 0x0, 0xc0, 0x4f, 0xc2, 0x95, 0xee } };
char *signature_name;
size_t i;
uint64_t current_ts, update_ts;
// Check the signature name. Make it specific enough (i.e. don't simply check for "Akeo")
// so that, besides hacking our server, it'll place an extra hurdle on any malicious entity
// into also fooling a C.A. to issue a certificate that passes our test.
signature_name = GetSignatureName(path, cert_country, (hDlg == INVALID_HANDLE_VALUE));
if (signature_name == NULL) {
uprintf("PKI: Could not get signature name");
if (hDlg != INVALID_HANDLE_VALUE)
MessageBoxExU(hDlg, lmprintf(MSG_284), lmprintf(MSG_283), MB_OK | MB_ICONERROR | MB_IS_RTL, selected_langid);
return TRUST_E_NOSIGNATURE;
}
for (i = 0; i < ARRAYSIZE(cert_name); i++) {
if (strcmp(signature_name, cert_name[i]) == 0)
break;
}
if (i >= ARRAYSIZE(cert_name)) {
uprintf("PKI: Signature '%s' is unexpected...", signature_name);
if ((hDlg == INVALID_HANDLE_VALUE) || (MessageBoxExU(hDlg,
lmprintf(MSG_285, signature_name), lmprintf(MSG_283),
MB_YESNO | MB_ICONWARNING | MB_IS_RTL, selected_langid) != IDYES))
return TRUST_E_EXPLICIT_DISTRUST;
}
trust_file.cbStruct = sizeof(trust_file);
trust_file.pcwszFilePath = utf8_to_wchar(path);
if (trust_file.pcwszFilePath == NULL) {
uprintf("PKI: Unable to convert '%s' to UTF16", path);
return ERROR_SEVERITY_ERROR | FAC(FACILITY_CERT) | ERROR_NOT_ENOUGH_MEMORY;
}
trust_data.cbStruct = sizeof(trust_data);
// NB: WTD_UI_ALL can result in ERROR_SUCCESS even if the signature validation fails,
// because it still prompts the user to run untrusted software, even after explicitly
// notifying them that the signature invalid (and of course Microsoft had to make
// that UI prompt a bit too similar to the other benign prompt you get when running
// trusted software, which, as per cert.org's assessment, may confuse non-security
// conscious-users who decide to gloss over these kind of notifications).
trust_data.dwUIChoice = WTD_UI_NONE;
// We just downloaded from the Internet, so we should be able to check revocation
trust_data.fdwRevocationChecks = WTD_REVOKE_WHOLECHAIN;
// 0x400 = WTD_MOTW for Windows 8.1 or later
trust_data.dwProvFlags = WTD_REVOCATION_CHECK_CHAIN | 0x400;
trust_data.dwUnionChoice = WTD_CHOICE_FILE;
trust_data.pFile = &trust_file;
r = WinVerifyTrustEx(INVALID_HANDLE_VALUE, &guid_generic_verify, &trust_data);
safe_free(trust_file.pcwszFilePath);
switch (r) {
case ERROR_SUCCESS:
// hDlg = INVALID_HANDLE_VALUE is used when validating the Fido PS1 script
if (hDlg == INVALID_HANDLE_VALUE)
break;
// Verify that the timestamp of the downloaded update is in the future of our current one.
// This is done to prevent the use of an officially signed, but older binary, as potential attack vector.
current_ts = GetSignatureTimeStamp(NULL);
if (current_ts == 0ULL) {
uprintf("PKI: Cannot retrieve the current binary's timestamp - Aborting update");
r = TRUST_E_TIME_STAMP;
} else {
update_ts = GetSignatureTimeStamp(path);
if (update_ts < current_ts) {
uprintf("PKI: Update timestamp (%" PRIi64 ") is younger than ours (%" PRIi64 ") - Aborting update", update_ts, current_ts);
r = TRUST_E_TIME_STAMP;
}
}
if ((r != ERROR_SUCCESS) && (force_update < 2))
MessageBoxExU(hDlg, lmprintf(MSG_300), lmprintf(MSG_299), MB_OK | MB_ICONERROR | MB_IS_RTL, selected_langid);
break;
case TRUST_E_NOSIGNATURE:
// Should already have been reported, but since we have a custom message for it...
uprintf("PKI: File does not appear to be signed: %s", WinPKIErrorString());
if (hDlg != INVALID_HANDLE_VALUE)
MessageBoxExU(hDlg, lmprintf(MSG_284), lmprintf(MSG_283), MB_OK | MB_ICONERROR | MB_IS_RTL, selected_langid);
break;
default:
uprintf("PKI: Failed to validate signature: %s", WinPKIErrorString());
if (hDlg != INVALID_HANDLE_VALUE)
MessageBoxExU(hDlg, lmprintf(MSG_240), lmprintf(MSG_283), MB_OK | MB_ICONERROR | MB_IS_RTL, selected_langid);
break;
}
return r;
}
// Why-oh-why am I the only one on github doing this openssl vs MS signature validation?!?
// For once, I'd like to find code samples from *OTHER PEOPLE* who went through this ordeal first...
BOOL ValidateOpensslSignature(BYTE* pbBuffer, DWORD dwBufferLen, BYTE* pbSignature, DWORD dwSigLen)
{
HCRYPTPROV hProv = 0;
HCRYPTHASH hHash = 0;
HCRYPTKEY hPubKey;
// We could load and convert an openssl PEM, but since we know what we need...
RSA_2048_PUBKEY pbMyPubKey = {
{ PUBLICKEYBLOB, CUR_BLOB_VERSION, 0, CALG_RSA_KEYX },
// $ openssl genrsa -aes256 -out private.pem 2048
// Generating RSA private key, 2048 bit long modulus
// e is 65537 (0x010001)
// => 0x010001 below. Also 0x31415352 = "RSA1"
{ 0x31415352, sizeof(pbMyPubKey.Modulus) * 8, 0x010001 },
{ 0 } // Modulus is initialized below
};
USHORT dwMyPubKeyLen = sizeof(pbMyPubKey);
BOOL r;
BYTE t;
int i, j;
// Get a handle to the default PROV_RSA_AES provider (AES so we get SHA-256 support).
// 2 passes in case we need to create a new container.
r = CryptAcquireContext(&hProv, NULL, NULL, PROV_RSA_AES, CRYPT_NEWKEYSET | CRYPT_VERIFYCONTEXT);
if (!r) {
uprintf("PKI: Could not create the default key container: %s", WinPKIErrorString());
goto out;
}
// Reverse the modulus bytes from openssl (and also remove the extra unwanted 0x00)
assert(sizeof(rsa_pubkey_modulus) >= sizeof(pbMyPubKey.Modulus));
for (i = 0; i < sizeof(pbMyPubKey.Modulus); i++)
pbMyPubKey.Modulus[i] = rsa_pubkey_modulus[sizeof(rsa_pubkey_modulus) -1 - i];
// Import our RSA public key so that the MS API can use it
r = CryptImportKey(hProv, (BYTE*)&pbMyPubKey.BlobHeader, dwMyPubKeyLen, 0, 0, &hPubKey);
if (!r) {
uprintf("PKI: Could not import public key: %s", WinPKIErrorString());
goto out;
}
// Create the hash object.
r = CryptCreateHash(hProv, CALG_SHA_256, 0, 0, &hHash);
if (!r) {
uprintf("PKI: Could not create empty hash: %s", WinPKIErrorString());
goto out;
}
// Compute the cryptographic hash of the buffer.
r = CryptHashData(hHash, pbBuffer, dwBufferLen, 0);
if (!r) {
uprintf("PKI: Could not hash data: %s", WinPKIErrorString());
goto out;
}
// Reverse the signature bytes
for (i = 0, j = dwSigLen - 1; i < j; i++, j--) {
t = pbSignature[i];
pbSignature[i] = pbSignature[j];
pbSignature[j] = t;
}
// Now that we have all of the public key, hash and signature data in a
// format that Microsoft can handle, we can call CryptVerifySignature().
r = CryptVerifySignature(hHash, pbSignature, dwSigLen, hPubKey, NULL, 0);
if (!r) {
// If the signature is invalid, clear the buffer so that
// we don't keep potentially nasty stuff in memory.
memset(pbBuffer, 0, dwBufferLen);
uprintf("Signature validation failed: %s", WinPKIErrorString());
}
out:
if (hHash)
CryptDestroyHash(hHash);
if (hProv)
CryptReleaseContext(hProv, 0);
return r;
}
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