private void ValidateHttp10(Package package)
{
// We should never see Expect: for HTTP/1.0 requests
if (package.HeadersMixed.ContainsKey("Expect")
&& package.HeadersMixed["Expect"].IndexOf
("100-continue", StringComparison.InvariantCultureIgnoreCase) < 0) {
package.Raise(Errors.Http10Expect);
}
}
public RuleProcessing Validate(Package package)
{
// Enforce RFC 2965 sec 3.3.5 and 9.1
// Bots wanting new-style cookies should send Cookie2
// FIXME: Amazon Kindle is broken; Amazon has been notified 9/24/08
if (package.HeadersMixed.ContainsKey("Cookie") &&
package.HeadersMixed["Cookie"].Contains("$Version=0") &&
!package.HeadersMixed.ContainsKey("Cookie2") &&
!package.Request.UserAgent.Contains("Kindle/")) {
package.Raise(Errors.InvalidCookies);
}
return RuleProcessing.Continue;
}
public RuleProcessing Validate(Package package)
{
if (package.Request.HttpMethod != "POST" && String.IsNullOrEmpty(package.Request.UserAgent))
package.Raise(Errors.UserAgentMissing);
// Broken spambots send URLs with various invalid characters
// Some broken browsers send the #vector in the referer field :(
// Worse yet, some Javascript client-side apps do the same in
// blatant violation of the protocol and good sense.
// if (strpos($package['request_uri'], "#") !== FALSE || strpos($package['headers_mixed']['Referer'], "#") !== FALSE) {
if (package.Request.RawUrl.Contains('#'))
package.RaiseStrict(Errors.Malicious);
// A pretty nasty SQL injection attack on IIS servers
if (package.Request.RawUrl.Contains(";DECLARE%20@"))
package.Raise(Errors.Malicious);
// Range: field exists and begins with 0
// Real user-agents do not start ranges at 0
// NOTE: this blocks the whois.sc bot. No big loss.
// Exceptions: MT (not fixable); LJ (refuses to fix; may be
// blocked again in the future); Facebook
if (package.HeadersMixed.ContainsKey("Range")
&& package.HeadersMixed["Range"].Contains("=0-")) {
if (!(
package.Request.UserAgent.StartsWith("MovableType") ||
package.Request.UserAgent.StartsWith("URI::Fetch") ||
package.Request.UserAgent.StartsWith("php-openid/") ||
package.Request.UserAgent.StartsWith("facebookexternalhit")
)) {
package.RaiseStrict(Errors.RangeHeaderZero);
}
}
// Content-Range is a response header, not a request header
if (package.HeadersMixed.ContainsKey("Content-Range"))
package.Raise(Errors.InvalidRangeHeader);
// Lowercase via is used by open proxies/referrer spammers
// Exceptions: Clearswift uses lowercase via (refuses to fix;
// may be blocked again in the future)
if (package.Request.Headers["via"] != null &&
!package.Request.Headers["via"].Contains("Clearswift") &&
!package.Request.UserAgent.Contains("CoralWebPrx"))
package.Raise(Errors.InvalidVia);
// pinappleproxy is used by referrer spammers
if (package.HeadersMixed.ContainsKey("Via")) {
string via = package.HeadersMixed["Via"].ToLowerInvariant();
if (via.Contains("pinappleproxy") || via.Contains("pcnetserver") || via.Contains("invisiware"))
package.Raise(Errors.BannedProxy);
}
// TE: if present must have Connection: TE
// RFC 2616 14.39
// Blocks Microsoft ISA Server 2004 in strict mode. Contact Microsoft
// to obtain a hotfix.
if (package.HeadersMixed.ContainsKey("Te")) {
if (Regex.Match(package.HeadersMixed["Connection"], @"\bTE\b").Success)
package.RaiseStrict(Errors.TeWithoutConnectionTe);
}
if (package.HeadersMixed.ContainsKey("Connection")) {
// Connection: keep-alive and close are mutually exclusive.
// Keep-Alive shouldn't appear twice, neither should Close.
var connection = package.HeadersMixed.GetValues("Connection");
var keepAlives = connection.Sum
(x => Regex.Matches(x, @"\bKeep-Alive\b", RegexOptions.IgnoreCase).Count);
var closes = connection.Sum
(x => Regex.Matches(x, @"\bClose\b", RegexOptions.IgnoreCase).Count);
if (keepAlives + closes > 1)
package.Raise(Errors.InvalidConnectionHeader);
// Keep-Alive format in RFC 2068; some bots mangle these headers
if (connection.Any(x => x.IndexOf
("Keep-Alive: ", StringComparison.InvariantCultureIgnoreCase) >= 0))
package.Raise(Errors.MaliciousConnectionHeader);
}
// Headers which are not seen from normal user agents; only malicious bots
if (package.HeadersMixed.ContainsKey("X-Aaaaaaaaaaaa") ||
package.HeadersMixed.ContainsKey("X-Aaaaaaaaaa"))
package.Raise(Errors.ProhibitedHeader);
// Proxy-Connection does not exist and should never be seen in the wild
// http://lists.w3.org/Archives/Public/ietf-http-wg-old/1999JanApr/0032.html
// http://lists.w3.org/Archives/Public/ietf-http-wg-old/1999JanApr/0040.html
if (package.HeadersMixed.ContainsKey("Proxy-Connection"))
package.RaiseStrict(Errors.ProxyConnectionHeaderPresent);
if (package.HeadersMixed.ContainsKey("Referer")) {
string referer = package.HeadersMixed["Referer"];
// Referer, if it exists, must not be blank
if (referer == String.Empty)
package.Raise(Errors.BlankReferer);
// Referer, if it exists, must contain a :
// While a relative URL is technically valid in Referer, all known
// legitimate user-agents send an absolute URL
if (!referer.Contains(":"))
package.Raise(Errors.CorruptReferer);
}
return RuleProcessing.Continue;
}
// Validates user agents claiming to be MSIE
private void ValidateMSIE(Package package)
{
AssertAccept(package);
// MSIE does NOT send "Windows ME" or "Windows XP" in the user agent
if (package.Request.UserAgent.Contains("Windows ME") ||
package.Request.UserAgent.Contains("Windows XP") ||
package.Request.UserAgent.Contains("Windows 2000") ||
package.Request.UserAgent.Contains("Win32"))
package.Raise(Errors.InvalidMSIEWindowsVersion);
// MSIE does NOT send Connection: TE but Akamai does
// Bypass this test when Akamai detected
if (package.HeadersMixed.ContainsKey("Akamai-Origin-Hop")) return;
// The latest version of IE for Windows CE also uses Connection: TE
if (package.Request.UserAgent.Contains("IEMobile")) return;
if (package.HeadersMixed.ContainsKey("Connection")) {
if (Regex.Match(package.HeadersMixed["Connection"], @"\bTE\b").Success) {
package.Raise(Errors.InvalidMSIEWithTE);
}
}
}
/* ====== Assertions ====== */
// Assert that the "Accept" HTTP header is present. Bona fide browsers all send this.
private void AssertAccept(Package package)
{
if (!package.HeadersMixed.ContainsKey("Accept"))
package.Raise(Errors.AcceptMissing);
}
/* ====== Movable Type ====== */
// See movabletype.inc.php in BB original.
private void ValidateMovableType(Package package)
{
// Is it a trackback?
if (package.Request.HttpMethod == "POST") {
if (package.HeadersMixed.ContainsKey("Range")
&& package.HeadersMixed["Range"] == "bytes=0-99999") {
package.Raise(Errors.InvalidRangeHeader);
}
}
}