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Deprecate encrypted BLOB checksum

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The MD5 checksum was calculated on unencrypted data. This offered a
possibility for a dictionary attack.

Signed-off-by: Simon Rozman <simon@rozman.si>
This commit is contained in:
Simon Rozman 2020-05-13 08:26:07 +02:00
parent 7897d0716c
commit a6bdb42ece
3 changed files with 33 additions and 11 deletions
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3
lib/EAPBase/include/Credentials.h
View File

@ -327,7 +327,8 @@ namespace eap
enum class enc_alg_t {
unknown = -1, ///< Unknown encryption
none = 0, ///< Unencrypted
native, ///< native module encryption
native, ///< native module encryption (version 2)
native_v1, ///< native module encryption (version 1, deprecated)
kph, ///< KPH encryption
};

18
lib/EAPBase/include/Module.h
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@ -364,6 +364,7 @@ namespace eap
///
/// \returns Encrypted data with 16B MD5 hash appended
///
[[deprecated("Unencrypted hash allows dictionary attacks")]]
std::vector<unsigned char> encrypt_md5(_In_ HCRYPTPROV hProv, _In_bytecount_(size) const void *data, _In_ size_t size) const;
@ -376,6 +377,7 @@ namespace eap
/// \returns Encrypted data with 16B MD5 hash appended
///
template<class _Elem, class _Traits, class _Ax>
[[deprecated("Unencrypted hash allows dictionary attacks")]]
std::vector<unsigned char> encrypt_md5(_In_ HCRYPTPROV hProv, _In_ const std::basic_string<_Elem, _Traits, _Ax> &val) const
{
return encrypt_md5(hProv, val.c_str(), val.length()*sizeof(_Elem));
@ -391,6 +393,7 @@ namespace eap
/// \returns Encrypted data with 16B MD5 hash appended
///
template<class _Traits, class _Ax>
[[deprecated("Unencrypted hash allows dictionary attacks")]]
std::vector<unsigned char> encrypt_md5(_In_ HCRYPTPROV hProv, _In_ const std::basic_string<wchar_t, _Traits, _Ax> &val) const
{
winstd::sanitizing_string val_utf8;
@ -451,7 +454,7 @@ namespace eap
template<class _Elem, class _Traits, class _Ax>
std::basic_string<_Elem, _Traits, _Ax> decrypt_str(_In_ HCRYPTPROV hProv, _In_bytecount_(size) const void *data, _In_ size_t size, _In_opt_ HCRYPTHASH hHash = NULL) const
{
std::vector<_Elem, sanitizing_allocator<_Elem> > buf(std::move(decrypt(hProv, data, size, hHash)));
std::vector<_Elem, sanitizing_allocator<_Elem> > buf(std::move(decrypt<_Elem, sanitizing_allocator<_Elem> >(hProv, data, size, hHash)));
return std::basic_string<_Elem, _Traits, _Ax>(buf.data(), buf.size());
}
@ -469,7 +472,7 @@ namespace eap
template<class _Traits, class _Ax>
std::basic_string<wchar_t, _Traits, _Ax> decrypt_str(_In_ HCRYPTPROV hProv, _In_bytecount_(size) const void *data, _In_ size_t size, _In_opt_ HCRYPTHASH hHash = NULL) const
{
winstd::sanitizing_string buf(std::move(decrypt_str(hProv, data, size, hHash)));
winstd::sanitizing_string buf(std::move(decrypt_str<char, std::char_traits<char>, sanitizing_allocator<char> >(hProv, data, size, hHash)));
std::basic_string<wchar_t, _Traits, _Ax> dec;
MultiByteToWideChar(CP_UTF8, 0, buf, dec);
return dec;
@ -486,6 +489,7 @@ namespace eap
/// \returns Decrypted data
///
template<class _Ty, class _Ax>
[[deprecated("Unencrypted hash allows dictionary attacks")]]
std::vector<_Ty, _Ax> decrypt_md5(_In_ HCRYPTPROV hProv, _In_bytecount_(size) const void *data, _In_ size_t size) const
{
// Create hash.
@ -522,6 +526,7 @@ namespace eap
/// \returns Decrypted string
///
template<class _Elem, class _Traits, class _Ax>
[[deprecated("Unencrypted hash allows dictionary attacks")]]
std::basic_string<_Elem, _Traits, _Ax> decrypt_str_md5(_In_ HCRYPTPROV hProv, _In_bytecount_(size) const void *data, _In_ size_t size) const
{
std::vector<_Elem, sanitizing_allocator<_Elem> > buf(std::move(decrypt_md5<_Elem, sanitizing_allocator<_Elem> >(hProv, data, size)));
@ -539,6 +544,7 @@ namespace eap
/// \returns Decrypted string
///
template<class _Traits, class _Ax>
[[deprecated("Unencrypted hash allows dictionary attacks")]]
std::basic_string<wchar_t, _Traits, _Ax> decrypt_str_md5(_In_ HCRYPTPROV hProv, _In_bytecount_(size) const void *data, _In_ size_t size) const
{
winstd::sanitizing_string buf(std::move(decrypt_str_md5<char, std::char_traits<char>, sanitizing_allocator<char> >(hProv, data, size)));
@ -573,7 +579,7 @@ namespace eap
throw winstd::win_runtime_error(__FUNCTION__ " CryptAcquireContext failed.");
// Decrypt data.
return std::move(decrypt_md5<unsigned char, winstd::sanitizing_allocator<unsigned char> >(cp, pDataIn, dwDataInSize));
return std::move(decrypt<unsigned char, winstd::sanitizing_allocator<unsigned char> >(cp, pDataIn, dwDataInSize));
#else
return sanitizing_blob(pDataIn, pDataIn + dwDataInSize);
#endif
@ -602,7 +608,7 @@ namespace eap
throw winstd::win_runtime_error(__FUNCTION__ " CryptAcquireContext failed.");
// Decrypt data.
std::vector<unsigned char, winstd::sanitizing_allocator<unsigned char> > data(std::move(decrypt_md5<unsigned char, winstd::sanitizing_allocator<unsigned char> >(cp, pDataIn, dwDataInSize)));
std::vector<unsigned char, winstd::sanitizing_allocator<unsigned char> > data(std::move(decrypt<unsigned char, winstd::sanitizing_allocator<unsigned char> >(cp, pDataIn, dwDataInSize)));
cursor_in cursor = { data.data(), data.data() + data.size() };
#else
@ -637,7 +643,7 @@ namespace eap
throw winstd::win_runtime_error(__FUNCTION__ " CryptAcquireContext failed.");
// Encrypt BLOB.
std::vector<unsigned char> data_enc(std::move(encrypt_md5(cp, data.data(), data.size())));
std::vector<unsigned char> data_enc(std::move(encrypt(cp, data.data(), data.size())));
// Copy encrypted BLOB to output.
*pdwDataOutSize = (DWORD)data_enc.size();
@ -685,7 +691,7 @@ namespace eap
throw winstd::win_runtime_error(__FUNCTION__ " CryptAcquireContext failed.");
// Encrypt BLOB.
std::vector<unsigned char> data_enc(std::move(encrypt_md5(cp, data.data(), data.size())));
std::vector<unsigned char> data_enc(std::move(encrypt(cp, data.data(), data.size())));
// Copy encrypted BLOB to output.
*pdwDataOutSize = (DWORD)data_enc.size();

23
lib/EAPBase/src/Credentials.cpp
View File

@ -436,12 +436,12 @@ void eap::credentials_pass::save(_In_ IXMLDOMDocument *pDoc, _In_ IXMLDOMNode *p
default:
// Use default encryption method for all others (including unencrypted).
vector<unsigned char> password_enc(std::move(m_module.encrypt_md5(cp, m_password)));
vector<unsigned char> password_enc(std::move(m_module.encrypt(cp, m_password)));
com_obj<IXMLDOMElement> pXmlElPassword;
if (FAILED(hr = eapxml::put_element_base64(pDoc, pConfigRoot, bstr(L"Password"), namespace_eapmetadata, password_enc.data(), password_enc.size(), std::addressof(pXmlElPassword))))
throw com_runtime_error(hr, __FUNCTION__ " Error creating <Password> element.");
pXmlElPassword->setAttribute(bstr(L"encryption"), variant(_L(PRODUCT_NAME_STR)));
pXmlElPassword->setAttribute(bstr(L"encryption"), variant(_L(PRODUCT_NAME_STR) _L(" v2")));
}
}
@ -464,7 +464,7 @@ void eap::credentials_pass::load(_In_ IXMLDOMNode *pConfigRoot)
if (FAILED(eapxml::get_attrib_value(pXmlElPassword, bstr(L"encryption"), encryption)))
encryption = NULL;
if (encryption && CompareStringEx(LOCALE_NAME_INVARIANT, NORM_IGNORECASE, encryption, encryption.length(), _L(PRODUCT_NAME_STR), -1, NULL, NULL, 0) == CSTR_EQUAL) {
if (encryption && CompareStringEx(LOCALE_NAME_INVARIANT, NORM_IGNORECASE, encryption, encryption.length(), _L(PRODUCT_NAME_STR) _L(" v2"), -1, NULL, NULL, 0) == CSTR_EQUAL) {
// Decode Base64.
winstd::base64_dec dec;
bool is_last;
@ -476,8 +476,23 @@ void eap::credentials_pass::load(_In_ IXMLDOMNode *pConfigRoot)
if (!cp.create(NULL, NULL, PROV_RSA_AES, CRYPT_VERIFYCONTEXT))
throw win_runtime_error(__FUNCTION__ " CryptAcquireContext failed.");
m_password = m_module.decrypt_str_md5<char_traits<wchar_t>, sanitizing_allocator<wchar_t> >(cp, password_enc.data(), password_enc.size());
m_password = m_module.decrypt_str<char_traits<wchar_t>, sanitizing_allocator<wchar_t> >(cp, password_enc.data(), password_enc.size());
m_enc_alg = enc_alg_t::native;
} else if (encryption && CompareStringEx(LOCALE_NAME_INVARIANT, NORM_IGNORECASE, encryption, encryption.length(), _L(PRODUCT_NAME_STR), -1, NULL, NULL, 0) == CSTR_EQUAL) {
// Decode Base64.
winstd::base64_dec dec;
bool is_last;
vector<unsigned char> password_enc;
dec.decode(password_enc, is_last, (BSTR)password, password.length());
// Prepare cryptographics provider.
crypt_prov cp;
if (!cp.create(NULL, NULL, PROV_RSA_AES, CRYPT_VERIFYCONTEXT))
throw win_runtime_error(__FUNCTION__ " CryptAcquireContext failed.");
#pragma warning(suppress: 4996) // Support for backward compatibility.
m_password = m_module.decrypt_str_md5<char_traits<wchar_t>, sanitizing_allocator<wchar_t> >(cp, password_enc.data(), password_enc.size());
m_enc_alg = enc_alg_t::native_v1;
} else if (encryption && CompareStringEx(LOCALE_NAME_INVARIANT, NORM_IGNORECASE, encryption, encryption.length(), _L("KPH"), -1, NULL, NULL, 0) == CSTR_EQUAL) {
// Decrypt password.
sanitizing_string password_utf8(std::move(kph_decrypt<OLECHAR>(password)));