Humhub 0.10.0-rc.1 - XSS / SQL Injection vulnerabilities

ID 1337DAY-ID-22996
Type zdt
Reporter Jos Wetzels
Modified 2014-12-10T00:00:00


Exploit for php platform in category web applications

                                            # Exploit Author: Jos Wetzels, Emiel Florijn
# Vendor Homepage:
# Software Link:
# Version: <= 0.10.0-rc.1
The Humhub [1] social networking kit versions 0.10.0-rc.1 and prior suffer from multiple persistent Cross-Site Scripting vulnerabilities, which have now been resolved in cooperation with the vendor [2], in various parts of the codebase.
1. Post/comment persistent XSS vulnerability
In the function actionPost() in "/protected/modules_core/post/controllers/PostController.php" [3], the $_POST variable is cleaned using a now-outdated version of the Yii framework's CmsInput extension stripClean() function [4], which improperly sanitizes user-input for XSS [5]. This situation also applies to actionPost() in "/protected/modules_core/comment/controllers/CommentController.php" [6]
Proof of Concept: making a post or comment with the URL-encoded form of either:
    <a href = "data:text/html,test">test</a>
    <img src = "index.php?r=user/auth/logout">
Will insert the corresponding HTML elements into the post/comment body.
2. Humhub-modules-mail [7] persistent XSS vulnerability
Humhub-modules-mail versions 0.5.9 and prior (when used in conjunction with Humhub 0.10.0-rc.1 or prior) is affected by the same vulnerability as described above. The vulnerable code is located in the function actionCreate() in "/controllers/MailController.php" [8]. Since every private message sent to a humhub user is also sent to the user's e-mail in the form of a HTML-enabled notification e-mail, an attacker can insert custom HTML elements in the body of the e-mail with grave consequences. It should be noted that the displayed in-system private messages are not susceptible to this attack vector.
3. Admin error logging persistent XSS vulnerability
In addition to the above, the admin error logging codebase is vulnerable to a persistent XSS vulnerability (with an even less restrictive set of injectable elements) as well. In most modules' error logging functionality, there is no XSS sanitation on the error message before passing it to the database and since there is no XSS sanitation before displaying error messages in the admin error logging interface, causing an error with a URL-encoded XSS string (different modules' error logging allow for different XSS vectors) in the parameter will cause the XSS to be persistently logged in the admin error logging interface, potentially allowing an attacker, among other attack vectors, to hijack the admin's session.
Proof of Concept: performing either of the following requests:
Wil insert the corresponding script elements into the admin error logging interface.
It should be noted that all XSS attack vectors require at least regular user-level access to the humhub system.

The Humhub [1] social networking kit versions 0.10.0-rc.1 and prior suffer from an SQL injection vulnerability, which has now been resolved in cooperation with the vendor [2], in its notification listing functionality allowing an attacker to obtain backend database access. In the actionIndex() function located in "/protected/modules_core/notification/controllers/ListController.php" [3] a check is performed on the unsanitized $lastEntryId variable (which is fetched from the 'from' GET parameter) to see if it is greater than 0. However, since PHP uses type-unstrict comparisons and $lastEntryId isn't guaranteed to be an integer, this allows an attacker to prefix their string of choice with any number of integers (so that $lastEntryId gets treated as an integer during the comparison) such that the comparison evaluates to true and $criteria->condition is injected with the otherwise unsanitized $lastEntryId, which can be any SQL injection.
Proof of Concept: Performing the following request
    index.php?r=notification/list/index&from=999) AND (CASE WHEN 0x30<(SELECT substring(password,1,1) FROM user_password WHERE id = 1) THEN 1 ELSE 0 END) AND (1=1
Allows an attacker to perform a binary search SQL injection. In addition, the SQL error handling of the function in question allows the attacker to perform a reflected Cross-Site Scripting attack.
Proof of Concept: Directing any user to the following link
    index.php/?r=notification/list/index&from=999) AND ("<iframe src = 'index.php/?r=user/auth/logout'>"=""
Will perform a CSRF attack against the target user.
It should be noted that the attack requires regular user-level authentication to the humhub system.

# [2018-04-01]  #