diff options
Diffstat (limited to 'system')
| -rw-r--r-- | system/core/Security.php | 158 |
1 files changed, 66 insertions, 92 deletions
diff --git a/system/core/Security.php b/system/core/Security.php index 4b42ed448..08cfcbe8f 100644 --- a/system/core/Security.php +++ b/system/core/Security.php @@ -492,16 +492,16 @@ class CI_Security { * Becomes: <blink> */ $pattern = '#' - .'<((/*\s*)([a-z0-9]+)(?=[^a-z0-9])' // tag start and name, followed by a non-tag character - .'[^>a-z0-9]*' // a valid attribute character immediately after the tag would count as a separator + .'<((?<closeTag>/*\s*)(?<tagName>[a-z0-9]+)(?=[^a-z0-9])' // tag start and name, followed by a non-tag character + .'[^\s\042\047a-z0-9>/=]*' // a valid attribute character immediately after the tag would count as a separator // optional attributes - .'([\s\042\047/=]+' // non-attribute characters, excluding > (tag close) for obvious reasons + .'(?<attributes>(?:[\s\042\047/=]*' // non-attribute characters, excluding > (tag close) for obvious reasons .'[^\s\042\047>/=]+' // attribute characters - // optional attribue-value - .'(\s*=\s*' // attribute-value separator - .'(\042[^\042]*\042|\047[^\047]*\047|[^\s\042\047=><`]*)' // single, double or non-quoted value - .')?' // end optional attribute-value group - .')*' // end optional attributes group + // optional attribute-value + .'(?:\s*=\s*' // attribute-value separator + .'(?:\042[^\042]*\042|\047[^\047]*\047|[^\s\042\047=><`]*)' // single, double or non-quoted value + .')?' // end optional attribute-value group + .')*)' // end optional attributes group .'[^>]*)>#isS'; // Note: It would be nice to optimize this for speed, BUT @@ -515,9 +515,6 @@ class CI_Security { while ($old_str !== $str); unset($old_str); - // Remove evil attributes such as style, onclick and xmlns - $str = $this->_remove_evil_attributes($str, $is_image); - /* * Sanitize naughty scripting elements * @@ -530,9 +527,11 @@ class CI_Security { * For example: eval('some code') * Becomes: eval('some code') */ - $str = preg_replace('#(alert|prompt|confirm|cmd|passthru|eval|exec|expression|system|fopen|fsockopen|file|file_get_contents|readfile|unlink)(\s*)\((.*?)\)#si', - '\\1\\2(\\3)', - $str); + $str = preg_replace( + '#(alert|prompt|confirm|cmd|passthru|eval|exec|expression|system|fopen|fsockopen|file|file_get_contents|readfile|unlink)(\s*)\((.*?)\)#si', + '\\1\\2(\\3)', + $str + ); // Final clean up // This adds a bit of extra precaution in case @@ -770,72 +769,6 @@ class CI_Security { // -------------------------------------------------------------------- /** - * Remove Evil HTML Attributes (like event handlers and style) - * - * It removes the evil attribute and either: - * - * - Everything up until a space. For example, everything between the pipes: - * - * <code> - * <a |style=document.write('hello');alert('world');| class=link> - * </code> - * - * - Everything inside the quotes. For example, everything between the pipes: - * - * <code> - * <a |style="document.write('hello'); alert('world');"| class="link"> - * </code> - * - * @param string $str The string to check - * @param bool $is_image Whether the input is an image - * @return string The string with the evil attributes removed - */ - protected function _remove_evil_attributes($str, $is_image) - { - $evil_attributes = array('on\w*', 'style', 'xmlns', 'formaction', 'form', 'xlink:href', 'FSCommand', 'seekSegmentTime'); - - if ($is_image === TRUE) - { - /* - * Adobe Photoshop puts XML metadata into JFIF images, - * including namespacing, so we have to allow this for images. - */ - unset($evil_attributes[array_search('xmlns', $evil_attributes)]); - } - - $pattern = '#(' // catch everything in the tag preceeding the evil attribute - .'<[a-z0-9]+(?=[^>a-z0-9])' // tag start and name, followed by a non-tag character - .'[^>a-z0-9]*' // a valid attribute character immediately after the tag would count as a separator - // optional attributes - .'([\s\042\047/=]+' // non-attribute characters, excluding > (tag close) for obvious reasons - .'[^\s\042\047>/=]+' // attribute characters - // optional attribue-value - .'(\s*=\s*' // attribute-value separator - .'(\042[^\042]*\042|\047[^\047]*\047|[^\s\042\047=><`]*)' // single, double or non-quoted value - .')?' // end optional attribute-value group - .')*' // end optional attributes group - .')' // end catching evil attribute prefix - // evil attribute starts here - .'([\s\042\047/=]+' // non-attribute characters (we'll replace that with a single space), again excluding '>' - .'('.implode('|', $evil_attributes).')' - .'\s*=\s*' // attribute-value separator - .'(\042[^\042]+\042|\047[^\047]+\047|[^\s\042\047=><`]+)' // attribute value; single, double or non-quotes - .')' // end evil attribute - .'#isS'; - - do - { - $count = 0; - $str = preg_replace($pattern, '$1 [removed]', $str, -1, $count); - } - while ($count); - - return $str; - } - - // -------------------------------------------------------------------- - - /** * Sanitize Naughty HTML * * Callback method for xss_clean() to remove naughty HTML elements. @@ -846,21 +779,59 @@ class CI_Security { */ protected function _sanitize_naughty_html($matches) { - static $naughty = array( + static $naughty_tags = array( 'alert', 'prompt', 'confirm', 'applet', 'audio', 'basefont', 'base', 'behavior', 'bgsound', 'blink', 'body', 'embed', 'expression', 'form', 'frameset', 'frame', 'head', 'html', 'ilayer', 'iframe', 'input', 'button', 'select', 'isindex', 'layer', 'link', 'meta', 'keygen', 'object', 'plaintext', 'style', 'script', 'textarea', 'title', 'math', 'video', 'svg', 'xml', 'xss' ); - // Is the element that we caught naughty? - // If not, just return it back. - if ( ! in_array(strtolower($matches[3]), $naughty, TRUE)) + static $evil_attributes = array( + 'on\w+', 'style', 'xmlns', 'formaction', 'form', 'xlink:href', 'FSCommand', 'seekSegmentTime' + ); + + // Is the element that we caught naughty? If so, escape it + if (in_array(strtolower($matches['tagName']), $naughty_tags, TRUE)) { - return $matches[0]; + return '<'.$matches[1].'>'; } + // For other tags, see if their attributes are "evil" and strip those + elseif (isset($matches['attributes'])) + { + // We'll need to catch all attributes separately first + $pattern = '#' + .'([\s\042\047/=]*)' // non-attribute characters, excluding > (tag close) for obvious reasons + .'(?<name>[^\s\042\047>/=]+)' // attribute characters + // optional attribute-value + .'(?:\s*=\s*\042[^\042]+\042|\s*=\s*\047[^\047]+\047|\s*=\s*[^\s\042\047=><`]+)?' // attribute-value separator + .'#i'; + + if ($count = preg_match_all($pattern, $matches['attributes'], $attributes, PREG_SET_ORDER | PREG_OFFSET_CAPTURE)) + { + // Since we'll be using substr_replace() below, we + // need to handle the attributes in reverse order, + // so we don't damage the string. + for ($i = $count - 1; $i > -1; $i--) + { + // Is it indeed an "evil" attribute? + if (preg_match('#^('.implode('|', $evil_attributes).')$#i', $attributes[$i]['name'][0])) + { + $matches['attributes'] = substr_replace( + $matches['attributes'], + ' [removed]', + $attributes[$i][0][1], + strlen($attributes[$i][0][0]) + ); + } + } - return '<'.$matches[1].'>'; + // Note: This will strip some non-space characters and/or + // reduce multiple spaces between attributes. + return '<'.$matches['closeTag'].$matches['tagName'].' '.trim($matches['attributes']).'>'; + } + } + + return $matches[0]; } // -------------------------------------------------------------------- @@ -880,12 +851,15 @@ class CI_Security { */ protected function _js_link_removal($match) { - return str_replace($match[1], - preg_replace('#href=.*?(?:(?:alert|prompt|confirm)(?:\(|&\#40;)|javascript:|livescript:|mocha:|charset=|window\.|document\.|\.cookie|<script|<xss|data\s*:)#si', - '', - $this->_filter_attributes(str_replace(array('<', '>'), '', $match[1])) - ), - $match[0]); + return str_replace( + $match[1], + preg_replace( + '#href=.*?(?:(?:alert|prompt|confirm)(?:\(|&\#40;)|javascript:|livescript:|mocha:|charset=|window\.|document\.|\.cookie|<script|<xss|data\s*:)#si', + '', + $this->_filter_attributes(str_replace(array('<', '>'), '', $match[1])) + ), + $match[0] + ); } // -------------------------------------------------------------------- |