[pki] add country code validation on signature check

* Also validate against the CN rather than the simple name, and require an exact match

src/pki.c

@@ -40,8 +40,11 @@
 #define szOID_NESTED_SIGNATURE "1.3.6.1.4.1.311.2.4.1"
 #endif
 
-// Signatures names we accept (may be suffixed, but the signature should start with one of those)
+// 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;
@@ -133,16 +136,17 @@ const char* WinPKIErrorString(void)
 }
 
 // Mostly from https://support.microsoft.com/en-us/kb/323809
-char* GetSignatureName(const char* path)
+char* GetSignatureName(const char* path, const char* country_code)
 {
 	static char szSubjectName[128];
+	static char szCountry[3];
 	char *p = NULL, *mpath = NULL;
 	BOOL r;
 	HMODULE hm;
 	HCERTSTORE hStore = NULL;
 	HCRYPTMSG hMsg = NULL;
 	PCCERT_CONTEXT pCertContext = NULL;
-	DWORD dwSize, dwEncoding, dwContentType, dwFormatType, dwSubjectSize;
+	DWORD dwSize, dwEncoding, dwContentType, dwFormatType;
 	PCMSG_SIGNER_INFO pSignerInfo = NULL;
 	DWORD dwSignerInfo = 0;
 	CERT_INFO CertInfo = { 0 };
@@ -209,15 +213,29 @@ char* GetSignatureName(const char* path)
 		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
-	dwSubjectSize = CertGetNameStringA(pCertContext, CERT_NAME_SIMPLE_DISPLAY_TYPE, 0, NULL,
+	dwSize = CertGetNameStringA(pCertContext, CERT_NAME_ATTR_TYPE, 0, szOID_COMMON_NAME,
 		szSubjectName, sizeof(szSubjectName));
-	if (dwSubjectSize <= 1) {
+	if (dwSize <= 1) {
 		uprintf("PKI: Failed to get Subject Name");
 		goto out;
 	}
 
-	uprintf("Downloaded executable is signed by '%s'", szSubjectName);
+	uprintf("Binary executable is signed by '%s' (%s)", szSubjectName, szCountry);
 	p = szSubjectName;
 
 out:
@@ -473,25 +491,21 @@ LONG ValidateSignature(HWND hDlg, const char* path)
 	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, len;
+	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);
+	signature_name = GetSignatureName(path, cert_country);
 	if (signature_name == NULL) {
 		uprintf("PKI: Could not get signature name");
 		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++) {
-		len = strlen(cert_name[i]);
-		if (strncmp(signature_name, cert_name[i], len) == 0) {
-			// Test for whitespace after the part we match, for added safety
-			if ((len >= strlen(signature_name)) || isspace(signature_name[len]))
-				break;
-		}
+		if (strcmp(signature_name, cert_name[i]) == 0)
+			break;
 	}
 	if (i >= ARRAYSIZE(cert_name)) {
 		uprintf("PKI: Signature '%s' is unexpected...", signature_name);

src/rufus.c

@@ -3166,7 +3166,7 @@ int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine
 	// Look for a .ini file in the current app directory
 	static_sprintf(ini_path, "%s\\rufus.ini", app_dir);
 	fd = fopenU(ini_path, ini_flags);	// Will create the file if portable mode is requested
-	vc |= (safe_strcmp(GetSignatureName(NULL), cert_name[0]) == 0);
+	vc |= (safe_strcmp(GetSignatureName(NULL, NULL), cert_name[0]) == 0);
 	if (fd != NULL) {
 		ini_file = ini_path;
 		fclose(fd);

src/rufus.h

@@ -488,7 +488,7 @@ extern BOOL IsBootableImage(const char* path);
 extern BOOL AppendVHDFooter(const char* vhd_path);
 extern int SetWinToGoIndex(void);
 extern int IsHDD(DWORD DriveIndex, uint16_t vid, uint16_t pid, const char* strid);
-extern char* GetSignatureName(const char* path);
+extern char* GetSignatureName(const char* path, const char* country_code);
 extern uint64_t GetSignatureTimeStamp(const char* path);
 extern LONG ValidateSignature(HWND hDlg, const char* path);
 extern BOOL IsFontAvailable(const char* font_name);

src/rufus.rc

@@ -33,7 +33,7 @@ LANGUAGE LANG_NEUTRAL, SUBLANG_NEUTRAL
 IDD_DIALOG DIALOGEX 12, 12, 242, 376
 STYLE DS_SETFONT | DS_MODALFRAME | DS_CENTER | WS_MINIMIZEBOX | WS_POPUP | WS_CAPTION | WS_SYSMENU
 EXSTYLE WS_EX_ACCEPTFILES
-CAPTION "Rufus 2.17.1195"
+CAPTION "Rufus 2.17.1196"
 FONT 8, "Segoe UI Symbol", 400, 0, 0x0
 BEGIN
     LTEXT           "Device",IDS_DEVICE_TXT,9,6,200,8
@@ -366,8 +366,8 @@ END
 //
 
 VS_VERSION_INFO VERSIONINFO
- FILEVERSION 2,17,1195,0
- PRODUCTVERSION 2,17,1195,0
+ FILEVERSION 2,17,1196,0
+ PRODUCTVERSION 2,17,1196,0
  FILEFLAGSMASK 0x3fL
 #ifdef _DEBUG
  FILEFLAGS 0x1L
@@ -384,13 +384,13 @@ BEGIN
         BEGIN
             VALUE "CompanyName", "Akeo Consulting (http://akeo.ie)"
             VALUE "FileDescription", "Rufus"
-            VALUE "FileVersion", "2.17.1195"
+            VALUE "FileVersion", "2.17.1196"
             VALUE "InternalName", "Rufus"
             VALUE "LegalCopyright", "� 2011-2017 Pete Batard (GPL v3)"
             VALUE "LegalTrademarks", "http://www.gnu.org/copyleft/gpl.html"
             VALUE "OriginalFilename", "rufus.exe"
             VALUE "ProductName", "Rufus"
-            VALUE "ProductVersion", "2.17.1195"
+            VALUE "ProductVersion", "2.17.1196"
         END
     END
     BLOCK "VarFileInfo"