CVE-2019-25095 (published 2023-01-05T08:15Z)

A vulnerability, which was classified as problematic, was found in kakwa LdapCherry up to 0.x. Affected is an unknown function of the component URL Handler. The manipulation leads to cross site scripting. It is possible to launch the attack remotely. Upgrading to version 1.0.0 is able to address this issue. The patch is identified as 6f98076281e9452fdb1adcd1bcbb70a6f968ade9. It is recommended to upgrade the affected component. VDB-217434 is the identifier assigned to this vulnerability.

CVSS v3 base score: 6.1, MEDIUM (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N)

Weakness information:
cwe_id: CWE-79
cwe_name: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
description: The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
extended_description: 
            Cross-site scripting (XSS) vulnerabilities occur when:
            
               Untrusted data enters a web application, typically from a web request.
               The web application dynamically generates a web page that contains this untrusted data.
               During page generation, the application does not prevent the data from containing content that is executable by a web browser, such as JavaScript, HTML tags, HTML attributes, mouse events, Flash, ActiveX, etc.
               A victim visits the generated web page through a web browser, which contains malicious script that was injected using the untrusted data.
               Since the script comes from a web page that was sent by the web server, the victim's web browser executes the malicious script in the context of the web server's domain.
               This effectively violates the intention of the web browser's same-origin policy, which states that scripts in one domain should not be able to access resources or run code in a different domain.
            
            There are three main kinds of XSS:
            
               
                  Type 1: Reflected XSS (or Non-Persistent) - 
         			The server reads data directly from the HTTP request and reflects it back in the HTTP response. Reflected XSS exploits occur when an attacker causes a victim to supply dangerous content to a vulnerable web application, which is then reflected back to the victim and executed by the web browser. The most common mechanism for delivering malicious content is to include it as a parameter in a URL that is posted publicly or e-mailed directly to the victim. URLs constructed in this manner constitute the core of many phishing schemes, whereby an attacker convinces a victim to visit a URL that refers to a vulnerable site. After the site reflects the attacker's content back to the victim, the content is executed by the victim's browser.
               
                  Type 2: Stored XSS (or Persistent) - 
               The application stores dangerous data in a database, message forum, visitor log, or other trusted data store. At a later time, the dangerous data is subsequently read back into the application and included in dynamic content. From an attacker's perspective, the optimal place to inject malicious content is in an area that is displayed to either many users or particularly interesting users. Interesting users typically have elevated privileges in the application or interact with sensitive data that is valuable to the attacker. If one of these users executes malicious content, the attacker may be able to perform privileged operations on behalf of the user or gain access to sensitive data belonging to the user. For example, the attacker might inject XSS into a log message, which might not be handled properly when an administrator views the logs.
            
               
                  Type 0: DOM-Based XSS - 
               In DOM-based XSS, the client performs the injection of XSS into the page; in the other types, the server performs the injection. DOM-based XSS generally involves server-controlled, trusted script that is sent to the client, such as Javascript that performs sanity checks on a form before the user submits it. If the server-supplied script processes user-supplied data and then injects it back into the web page (such as with dynamic HTML), then DOM-based XSS is possible.
            
            
            Once the malicious script is injected, the attacker can perform a variety of malicious activities. The attacker could transfer private information, such as cookies that may include session information, from the victim's machine to the attacker. The attacker could send malicious requests to a web site on behalf of the victim, which could be especially dangerous to the site if the victim has administrator privileges to manage that site. Phishing attacks could be used to emulate trusted web sites and trick the victim into entering a password, allowing the attacker to compromise the victim's account on that web site. Finally, the script could exploit a vulnerability in the web browser itself possibly taking over the victim's machine, sometimes referred to as "drive-by hacking."
            In many cases, the attack can be launched without the victim even being aware of it. Even with careful users, attackers frequently use a variety of methods to encode the malicious portion of the attack, such as URL encoding or Unicode, so the request looks less suspicious.
         
         

Fix information:
repo_url: https://github.com/kakwa/ldapcherry
commit_details: repo_url: https://github.com/kakwa/ldapcherry
author: John Thiltges
author_date: 2019-01-02 14:31:10-06:00
msg: Protect against XSS vulnerabilities in URL redirection

- Switch from base64 to URL encoding for the passing the URL, using the built-in Mako filtering
- Apply HTML filtering to Mako output by default
- Disable HTML filtering for nested templates in adduser, modify, and selfmodify
repository: repo_url: https://github.com/kakwa/ldapcherry
repo_name: kakwa/ldapcherry
description: Web UI for managing users and groups in multiple directory services.
repo_language: Python
owner: kakwa
file_changes: filename: __init__.py
change_type: ModificationType.MODIFY
diff: @@ -15,7 +15,7 @@ import logging
 import logging.handlers
 from operator import itemgetter
 from socket import error as socket_error
-import base64
+import urllib
 import cgi
 
 from exceptions import *
@@ -387,7 +387,8 @@ class LdapCherry(object):
         )
         # preload templates
         self.temp_lookup = lookup.TemplateLookup(
-            directories=self.template_dir, input_encoding='utf-8'
+            directories=self.template_dir, input_encoding='utf-8',
+            default_filters=['unicode', 'h']
             )
         # load each template
         self.temp = {}
@@ -573,7 +574,7 @@ class LdapCherry(object):
 
     def _check_auth(self, must_admin, redir_login=True):
         """ check if a user is autheticated and, optionnaly an administrator
-        if user not authentifaced -> redirection to login page (with base64
+        if user not authenticated -> redirect to login page (with escaped URL
             of the originaly requested page (redirection after login)
         if user authenticated, not admin and must_admin enabled -> 403 error
         @boolean must_admin: flag "user must be an administrator to access
@@ -588,13 +589,13 @@ class LdapCherry(object):
             qs = ''
         else:
             qs = '?' + cherrypy.request.query_string
-        # base64 of the requested URL
-        b64requrl = base64.b64encode(cherrypy.url() + qs)
+        # Escaped version of the requested URL
+        quoted_requrl = urllib.quote_plus(cherrypy.url() + qs)
         if not username:
-            # return to login page (with base64 of the url in query string
+            # return to login page (with quoted url in query string)
             if redir_login:
                 raise cherrypy.HTTPRedirect(
-                    "/signin?url=%(url)s" % {'url': b64requrl},
+                    "/signin?url=%(url)s" % {'url': quoted_requrl},
                     )
             else:
                 raise cherrypy.HTTPError(
@@ -606,7 +607,7 @@ class LdapCherry(object):
                 or not cherrypy.session['connected']:
             if redir_login:
                 raise cherrypy.HTTPRedirect(
-                    "/signin?url=%(url)s" % {'url': b64requrl},
+                    "/signin?url=%(url)s" % {'url': quoted_requrl},
                     )
             else:
                 raise cherrypy.HTTPError(
@@ -631,7 +632,7 @@ class LdapCherry(object):
         else:
             if redir_login:
                 raise cherrypy.HTTPRedirect(
-                    "/signin?url=%(url)s" % {'url': b64requrl},
+                    "/signin?url=%(url)s" % {'url': quoted_requrl},
                     )
             else:
                 raise cherrypy.HTTPError(
@@ -919,7 +920,7 @@ class LdapCherry(object):
             if url is None:
                 redirect = "/"
             else:
-                redirect = base64.b64decode(url)
+                redirect = url
             raise cherrypy.HTTPRedirect(redirect)
         else:
             message = "login failed for user '%(user)s'" % {
@@ -932,7 +933,7 @@ class LdapCherry(object):
             if url is None:
                 qs = ''
             else:
-                qs = '?url=' + url
+                qs = '?url=' + urllib.quote_plus(url)
             raise cherrypy.HTTPRedirect("/signin" + qs)
 
     @cherrypy.expose

programming_language: Python
filename: adduser.tmpl
change_type: ModificationType.MODIFY
diff: @@ -9,11 +9,11 @@
               <form method='POST' autocomplete="off" action='/adduser' role="form" class="form-signin" id=form>
               <fieldset>
               <legend>Fill new user's attributes:</legend>
-              ${form}
+              ${form | n}
               </fieldset>
               <fieldset>
               <legend>Enable/Disable user's roles:</legend>
-              ${roles}
+              ${roles | n}
               </fieldset>
               <div class="form-group">
                 <div class="input-group">

programming_language: HTML
filename: login.tmpl
change_type: ModificationType.MODIFY
diff: @@ -4,13 +4,13 @@
     <div class="row clearfix" style="margin-top:30px">
         <div class="col-md-4 column"></div>
         <div class="col-md-4 column well">
-<%
-if url is None:
-    qs=''
-else:
-    qs='?url=' + url
-%>
-            <form method='POST' action='/login${qs}' role="form" class="form-signin">
+            <form method='POST' role="form" class="form-signin"
+% if url:
+                action='login?url=${url | u}'
+% else:
+                action='login'
+% endif
+            >
               <div class="form-group">
               <h2 class="form-signin-heading">Please sign in</h2>
                 <div class="input-group">

programming_language: HTML
filename: modify.tmpl
change_type: ModificationType.MODIFY
diff: @@ -9,11 +9,11 @@
               <form method='POST' action='/modify' role="form" class="form-signin" id="form">
               <fieldset>
               <legend>Modify user's attributes:</legend>
-              ${form}
+              ${form | n}
               </fieldset>
               <fieldset>
               <legend>Enable/Disable user's roles:</legend>
-              ${roles}
+              ${roles | n}
               </fieldset>
               % if len(standalone_groups) != 0:
               <fieldset>

programming_language: HTML
filename: selfmodify.tmpl
change_type: ModificationType.MODIFY
diff: @@ -8,7 +8,7 @@
             <div class="well well-sm">
               <form method='POST' action='/selfmodify' autocomplete="off" role="form" class="form-signin" id="form">
               <legend>Modify your attributes:</legend>
-              ${form}
+              ${form | n}
               </fieldset>
               <div class="form-group">
                 <div class="input-group">

programming_language: HTML