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-rw-r--r--includes/account_stuff.php357
1 files changed, 357 insertions, 0 deletions
diff --git a/includes/account_stuff.php b/includes/account_stuff.php
index caa7dc7..b6fdd7a 100644
--- a/includes/account_stuff.php
+++ b/includes/account_stuff.php
@@ -284,4 +284,361 @@ function hideall() {
</body>
</html><?
}
+
+ /**
+ * Produces a log entry with the error message with log level E_USER_WARN
+ * and a random ID an returns a message that can be displayed to the user
+ * including the generated ID
+ *
+ * @param $errormessage string
+ * The error message that should be logged
+ * @return string containing the generated ID that can be displayed to the
+ * user
+ */
+ function failWithId($errormessage) {
+ $errorId = rand();
+ trigger_error("$errormessage. ID: $errorId", E_USER_WARNING);
+ return sprintf(_("Something went wrong when processing your request. ".
+ "Please contact %s for help and provide them with the ".
+ "following ID: %d"),
+ "<a href='mailto:support@cacert.org?subject=System%20Error%20-%20".
+ "ID%3A%20$errorId'>support@cacert.org</a>",
+ $errorId);
+ }
+
+ /**
+ * Checks whether the given CSR contains a vulnerable key
+ *
+ * @param $csr string
+ * The CSR to be checked
+ * @param $encoding string [optional]
+ * The encoding the CSR is in (for the "-inform" parameter of OpenSSL,
+ * currently only "PEM" (default) or "DER" allowed)
+ * @return string containing the reason if the key is considered weak,
+ * empty string otherwise
+ */
+ function checkWeakKeyCSR($csr, $encoding = "PEM")
+ {
+ // non-PEM-encodings may be binary so don't use echo
+ $descriptorspec = array(
+ 0 => array("pipe", "r"), // STDIN for child
+ 1 => array("pipe", "w"), // STDOUT for child
+ );
+ $encoding = escapeshellarg($encoding);
+ $proc = proc_open("openssl req -inform $encoding -text -noout",
+ $descriptorspec, $pipes);
+
+ if (is_resource($proc))
+ {
+ fwrite($pipes[0], $csr);
+ fclose($pipes[0]);
+
+ $csrText = "";
+ while (!feof($pipes[1]))
+ {
+ $csrText .= fread($pipes[1], 8192);
+ }
+ fclose($pipes[1]);
+
+ if (($status = proc_close($proc)) !== 0 || $csrText === "")
+ {
+ return _("I didn't receive a valid Certificate Request, hit ".
+ "the back button and try again.");
+ }
+ } else {
+ return failWithId("checkWeakKeyCSR(): Failed to start OpenSSL");
+ }
+
+
+ return checkWeakKeyText($csrText);
+ }
+
+ /**
+ * Checks whether the given X509 certificate contains a vulnerable key
+ *
+ * @param $cert string
+ * The X509 certificate to be checked
+ * @param $encoding string [optional]
+ * The encoding the certificate is in (for the "-inform" parameter of
+ * OpenSSL, currently only "PEM" (default), "DER" or "NET" allowed)
+ * @return string containing the reason if the key is considered weak,
+ * empty string otherwise
+ */
+ function checkWeakKeyX509($cert, $encoding = "PEM")
+ {
+ // non-PEM-encodings may be binary so don't use echo
+ $descriptorspec = array(
+ 0 => array("pipe", "r"), // STDIN for child
+ 1 => array("pipe", "w"), // STDOUT for child
+ );
+ $encoding = escapeshellarg($encoding);
+ $proc = proc_open("openssl x509 -inform $encoding -text -noout",
+ $descriptorspec, $pipes);
+
+ if (is_resource($proc))
+ {
+ fwrite($pipes[0], $cert);
+ fclose($pipes[0]);
+
+ $certText = "";
+ while (!feof($pipes[1]))
+ {
+ $certText .= fread($pipes[1], 8192);
+ }
+ fclose($pipes[1]);
+
+ if (($status = proc_close($proc)) !== 0 || $certText === "")
+ {
+ return _("I didn't receive a valid Certificate Request, hit ".
+ "the back button and try again.");
+ }
+ } else {
+ return failWithId("checkWeakKeyCSR(): Failed to start OpenSSL");
+ }
+
+
+ return checkWeakKeyText($certText);
+ }
+
+ /**
+ * Checks whether the given SPKAC contains a vulnerable key
+ *
+ * @param $spkac string
+ * The SPKAC to be checked
+ * @param $spkacname string [optional]
+ * The name of the variable that contains the SPKAC. The default is
+ * "SPKAC"
+ * @return string containing the reason if the key is considered weak,
+ * empty string otherwise
+ */
+ function checkWeakKeySPKAC($spkac, $spkacname = "SPKAC")
+ {
+ /* Check for the debian OpenSSL vulnerability */
+
+ $spkac = escapeshellarg($spkac);
+ $spkacname = escapeshellarg($spkacname);
+ $spkacText = `echo $spkac | openssl spkac -spkac $spkacname`;
+ if ($spkacText === null) {
+ return _("I didn't receive a valid Certificate Request, hit the ".
+ "back button and try again.");
+ }
+
+ return checkWeakKeyText($spkacText);
+ }
+
+ /**
+ * Checks whether the given text representation of a CSR or a SPKAC contains
+ * a weak key
+ *
+ * @param $text string
+ * The text representation of a key as output by the
+ * "openssl <foo> -text -noout" commands
+ * @return string containing the reason if the key is considered weak,
+ * empty string otherwise
+ */
+ function checkWeakKeyText($text)
+ {
+ /* Which public key algorithm? */
+ if (!preg_match('/^\s*Public Key Algorithm: ([^\s]+)$/m', $text,
+ $algorithm))
+ {
+ return failWithId("checkWeakKeyText(): Couldn't extract the ".
+ "public key algorithm used");
+ } else {
+ $algorithm = $algorithm[1];
+ }
+
+
+ if ($algorithm === "rsaEncryption")
+ {
+ if (!preg_match('/^\s*RSA Public Key: \((\d+) bit\)$/m', $text,
+ $keysize))
+ {
+ return failWithId("checkWeakKeyText(): Couldn't parse the RSA ".
+ "key size");
+ } else {
+ $keysize = intval($keysize[1]);
+ }
+
+ if ($keysize < 1024)
+ {
+ return sprintf(_("The keys that you use are very small ".
+ "and therefore insecure. Please generate stronger ".
+ "keys. More information about this issue can be ".
+ "found in %sthe wiki%s"),
+ "<a href='//wiki.cacert.org/WeakKeys#SmallKey'>",
+ "</a>");
+ } elseif ($keysize < 2048) {
+ // not critical but log so we have some statistics about
+ // affected users
+ trigger_error("checkWeakKeyText(): Certificate for small ".
+ "key (< 2048 bit) requested", E_USER_NOTICE);
+ }
+
+
+ $debianVuln = checkDebianVulnerability($text, $keysize);
+ if ($debianVuln === true)
+ {
+ return sprintf(_("The keys you use have very likely been ".
+ "generated with a vulnerable version of OpenSSL which ".
+ "was distributed by debian. Please generate new keys. ".
+ "More information about this issue can be found in ".
+ "%sthe wiki%s"),
+ "<a href='//wiki.cacert.org/WeakKeys#DebianVulnerability'>",
+ "</a>");
+ } elseif ($debianVuln === false) {
+ // not vulnerable => do nothing
+ } else {
+ return failWithId("checkWeakKeyText(): Something went wrong in".
+ "checkDebianVulnerability()");
+ }
+
+ if (!preg_match('/^\s*Exponent: (\d+) \(0x[0-9a-fA-F]+\)$/m', $text,
+ $exponent))
+ {
+ return failWithId("checkWeakKeyText(): Couldn't parse the RSA ".
+ "exponent");
+ } else {
+ $exponent = $exponent[1]; // exponent might be very big =>
+ //handle as string using bc*()
+
+ if (bccomp($exponent, "3") === 0)
+ {
+ return sprintf(_("The keys you use might be insecure. ".
+ "Although there is currently no known attack for ".
+ "reasonable encryption schemes, we're being ".
+ "cautious and don't allow certificates for such ".
+ "keys. Please generate stronger keys. More ".
+ "information about this issue can be found in ".
+ "%sthe wiki%s"),
+ "<a href='//wiki.cacert.org/WeakKeys#SmallExponent'>",
+ "</a>");
+ } elseif (!(bccomp($exponent, "65537") >= 0 &&
+ (bccomp($exponent, "100000") === -1 ||
+ // speed things up if way smaller than 2^256
+ bccomp($exponent, bcpow("2", "256")) === -1) )) {
+ // 65537 <= exponent < 2^256 recommended by NIST
+ // not critical but log so we have some statistics about
+ // affected users
+ trigger_error("checkWeakKeyText(): Certificate for ".
+ "unsuitable exponent '$exponent' requested",
+ E_USER_NOTICE);
+ }
+ }
+ }
+
+ /* No weakness found */
+ return "";
+ }
+
+ /**
+ * Reimplement the functionality of the openssl-vulnkey tool
+ *
+ * @param $text string
+ * The text representation of a key as output by the
+ * "openssl <foo> -text -noout" commands
+ * @param $keysize int [optional]
+ * If the key size is already known it can be provided so it doesn't
+ * have to be parsed again. This also skips the check whether the key
+ * is an RSA key => use wisely
+ * @return TRUE if key is vulnerable, FALSE otherwise, NULL in case of error
+ */
+ function checkDebianVulnerability($text, $keysize = 0)
+ {
+ $keysize = intval($keysize);
+
+ if ($keysize === 0)
+ {
+ /* Which public key algorithm? */
+ if (!preg_match('/^\s*Public Key Algorithm: ([^\s]+)$/m', $text,
+ $algorithm))
+ {
+ trigger_error("checkDebianVulnerability(): Couldn't extract ".
+ "the public key algorithm used", E_USER_WARNING);
+ return null;
+ } else {
+ $algorithm = $algorithm[1];
+ }
+
+ if ($algorithm !== "rsaEncryption") return false;
+
+ /* Extract public key size */
+ if (!preg_match('/^\s*RSA Public Key: \((\d+) bit\)$/m', $text,
+ $keysize))
+ {
+ trigger_error("checkDebianVulnerability(): Couldn't parse the ".
+ "RSA key size", E_USER_WARNING);
+ return null;
+ } else {
+ $keysize = intval($keysize[1]);
+ }
+ }
+
+ // $keysize has been made sure to contain an int
+ $blacklist = "/usr/share/openssl-blacklist/blacklist.RSA-$keysize";
+ if (!(is_file($blacklist) && is_readable($blacklist)))
+ {
+ if (in_array($keysize, array(512, 1024, 2048, 4096)))
+ {
+ trigger_error("checkDebianVulnerability(): Blacklist for ".
+ "$keysize bit keys not accessible. Expected at ".
+ "$blacklist", E_USER_ERROR);
+ return null;
+ }
+
+ trigger_error("checkDebianVulnerability(): $blacklist is not ".
+ "readable. Unsupported key size?", E_USER_WARNING);
+ return false;
+ }
+
+
+ /* Extract RSA modulus */
+ if (!preg_match('/^\s*Modulus \(\d+ bit\):\n'.
+ '((?:\s*[0-9a-f][0-9a-f]:(?:\n)?)+[0-9a-f][0-9a-f])$/m',
+ $text, $modulus))
+ {
+ trigger_error("checkDebianVulnerability(): Couldn't extract the ".
+ "RSA modulus", E_USER_WARNING);
+ return null;
+ } else {
+ $modulus = $modulus[1];
+ // strip whitespace and colon leftovers
+ $modulus = str_replace(array(" ", "\t", "\n", ":"), "", $modulus);
+
+ // when using "openssl xxx -text" first byte was 00 in all my test
+ // cases but 00 not present in the "openssl xxx -modulus" output
+ if ($modulus[0] === "0" && $modulus[1] === "0")
+ {
+ $modulus = substr($modulus, 2);
+ } else {
+ trigger_error("checkDebianVulnerability(): First byte is not ".
+ "zero", E_USER_NOTICE);
+ }
+
+ $modulus = strtoupper($modulus);
+ }
+
+
+ /* calculate checksum and look it up in the blacklist */
+ $checksum = substr(sha1("Modulus=$modulus\n"), 20);
+
+ // $checksum and $blacklist should be safe, but just to make sure
+ $checksum = escapeshellarg($checksum);
+ $blacklist = escapeshellarg($blacklist);
+ exec("grep $checksum $blacklist", $dummy, $debianVuln);
+ if ($debianVuln === 0) // grep returned something => it is on the list
+ {
+ return true;
+ } elseif ($debianVuln === 1) { // grep returned nothing
+ return false;
+ } else {
+ trigger_error("checkDebianVulnerability(): Something went wrong ".
+ "when looking up the key with checksum $checksum in the ".
+ "blacklist $blacklist", E_USER_ERROR);
+ return null;
+ }
+
+ // Should not get here
+ return null;
+ }
?>