WordPress Better WP Security Cross Site Scripting

2012-05-10 / 2012-05-11
Risk: Low
Local: No
Remote: Yes

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Wordpress Security audit better_wp_security 1. Cross-site scripting (reflected) Summary Severity: High Confidence: Certain Host: Path: /wp-admin/admin.php?page=better_wp_security Issue detail The value of the User-Agent HTTP header is copied into the HTML document as plain text between tags. The payload a7123<script>alert(1)</script>78089b4648b was submitted in the User-Agent HTTP header. This input was echoed unmodified in the application's response. This proof-of-concept attack demonstrates that it is possible to inject arbitrary JavaScript into the application's response. Issue background Reflected cross-site scripting vulnerabilities arise when data is copied from a request and echoed into the application's immediate response in an unsafe way. An attacker can use the vulnerability to construct a request which, if issued by another application user, will cause JavaScript code supplied by the attacker to execute within the user's browser in the context of that user's session with the application. The attacker-supplied code can perform a wide variety of actions, such as stealing the victim's session token or login credentials, performing arbitrary actions on the victim's behalf, and logging their keystrokes. Users can be induced to issue the attacker's crafted request in various ways. For example, the attacker can send a victim a link containing a malicious URL in an email or instant message. They can submit the link to popular web sites that allow content authoring, for example in blog comments. And they can create an innocuous looking web site which causes anyone viewing it to make arbitrary cross-domain requests to the vulnerable application (using either the GET or the POST method). The security impact of cross-site scripting vulnerabilities is dependent upon the nature of the vulnerable application, the kinds of data and functionality which it contains, and the other applications which belong to the same domain and organisation. If the application is used only to display non-sensitive public content, with no authentication or access control functionality, then a cross-site scripting flaw may be considered low risk. However, if the same application resides on a domain which can access cookies for other more security-critical applications, then the vulnerability could be used to attack those other applications, and so may be considered high risk. Similarly, if the organisation which owns the application is a likely target for phishing attacks, then the vulnerability could be leveraged to lend credibility to such attacks, by injecting Trojan functionality into the vulnerable application, and exploiting users' trust in the organisation in order to capture credentials for other applications which it owns. In many kinds of application, such as those providing online banking functionality, cross-site scripting should always be considered high risk. Issue remediation In most situations where user-controllable data is copied into application responses, cross-site scripting attacks can be prevented using two layers of defences: Input should be validated as strictly as possible on arrival, given the kind of content which it is expected to contain. For example, personal names should consist of alphabetical and a small range of typographical characters, and be relatively short; a year of birth should consist of exactly four numerals; email addresses should match a well-defined regular expression. Input which fails the validation should be rejected, not sanitised. User input should be HTML-encoded at any point where it is copied into application responses. All HTML metacharacters, including < > " ' and =, should be replaced with the corresponding HTML entities (&lt; &gt; etc). In cases where the application's functionality allows users to author content using a restricted subset of HTML tags and attributes (for example, blog comments which allow limited formatting and linking), it is necessary to parse the supplied HTML to validate that it does not use any dangerous syntax; this is a non-trivial task. Request GET /wp-admin/admin.php?page=better_wp_security HTTP/1.1 Host: User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:11.0) Gecko/20100101 Firefox/11.0a7123<script>alert(1)</script>78089b4648b Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip, deflate Proxy-Connection: keep-alive Referer: Cookie: wordpress_5c016e8f0f95f039102cbe8366c5c7f3=admin%7C1333587813%7C73fe3e4d525d2460588947c4b7a03114; wp-settings-1=widgets_access%3Doff%26uploader%3D1; wp-settings-time-1=1333368822; wordpress_test_cookie=WP+Cookie+check; wordpress_logged_in_5c016e8f0f95f039102cbe8366c5c7f3=admin%7C1333587813%7C7b961d6e5caea2c784f282c5ed426964; bb2_screener_=1333415711+; PHPSESSID=j3l493obmauq7akebg8g3jb4k3 Response HTTP/1.1 200 OK Date: Tue, 03 Apr 2012 02:05:00 GMT Server: Apache/2.2.20 (Ubuntu) X-Powered-By: PHP/5.3.6-13ubuntu3.6 Expires: Wed, 11 Jan 1984 05:00:00 GMT Last-Modified: Tue, 03 Apr 2012 02:05:00 GMT Cache-Control: no-cache, must-revalidate, max-age=0 Pragma: no-cache X-Frame-Options: SAMEORIGIN Vary: Accept-Encoding Content-Length: 35849 Content-Type: text/html; charset=UTF-8 <!DOCTYPE html> <!--[if IE 8]> <html xmlns="http://www.w3.org/1999/xhtml" class="ie8" dir="ltr" lang="en-US"> <![endif]--> <!--[if !(IE 8) ]><!--> <html xmlns="http://www.w3.org/1999/xhtml" dir="ltr ...[SNIP]... <strong>Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:11.0) Gecko/20100101 Firefox/11.0a7123<script>alert(1)</script>78089b4648b</strong> ...[SNIP]... -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iQIcBAEBAgAGBQJPrDiKAAoJEJPBwXYLR9Vt/hkQAKNGQhkWEzZA8t3+HmC6Japy /YbUa+YEBjo9tBMU6fVVkmprl4kTAFUxXkecxHO7nac6OEtW5NqskZkikywn4x7n /I5ZP+M8uns9pB0FXbhK9SR80BlRnvwcMGlJi7fqf83zi2A1NAbzhBUX48Ibk45C jqT5OGBE7Ktg9MRL3GxfZeSvcmfooczhGipvHBFUOkv1sy/vlKOQJdqliAnWod1/ /gWY42dbkgDEI62ddVdF6s1BSoenMIbNFJSXpdSuz0DBm7soliKwxFmSK613o53O BJ4+YQOCLeuQwnW7Jsf4v6u8XhgW+EBPkBk+jdR6Bg1DaDOICkyvWNu07xZpJWtP ijFUovpl3PM3HgyEpoRJR2355TAoOLjkifxm2fO8FEp/TxuQdCT33Gr5UcuA6hnp v7FZPcfDofYJm+EQgzIwdxv4NuC88EW1+WddO+t9MXTY/fi87oD3Aqgv+guXuyMp J3kcwqzPKQXYlauQRq4V/RlUClrwCk9qDqa2ihan7Axl8XIfaP+ECyAasqAUl/Uh OUZMxJNxzsKBv6BYlOOp4ipuVzBxO1KKOldJrTzV5VcwtQ5HZMoX+Lrv4BpCzxwB 1jL5SkuxP7zyJZrO6X/Comn41Wos/JFnXMvFWy1UyaEsQFC5NmkOsv5OEwKtiBQR Jv/axPAeo7/88PR2ZrGY =0weS -----END PGP SIGNATURE-----

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