Monday, 29 December 2014

CVE-2014-7292 Newtelligence dasBlog Dest Redirect Privilege Escalation Web Application Zero Day Bug

Exploit Title: Newtelligence dasBlog Dest Redirect Privilege Escalation Vulnerability
Product: dasBlog
Vendor:  Newtelligence
Vulnerable Versions: 2.3 (2.3.9074.18820) 2.2 (2.2.8279.16125) 2.1(2.1.8102.813)
Tested Version: 2.3 (2.3.9074.18820)
Advisory Publication: OCT 15, 2014
Latest Update:   OCT 15, 2014
Vulnerability Type: URL Redirection to Untrusted Site ('Open Redirect') [CWE-601]
CVE Reference: *
Impact CVSS Severity (version 2.0):
CVSS v2 Base Score: 5.8 (MEDIUM) (AV:N/AC:M/Au:N/C:P/I:P/A:N) (legend)
Impact Subscore: 4.9
Exploitability Subscore: 8.6
CVSS Version 2 Metrics:
Access Vector: Network exploitable; Victim must voluntarily interact with attack mechanism
Access Complexity: Medium
Authentication: Not required to exploit
Impact Type: Allows unauthorized disclosure of information; Allows unauthorized modification
Writer and Reporter: Jing Wang [School of Physical and Mathematical Sciences (SPMS), Nanyang Technological University (NTU), Singapore] (@justqdjing)

Proposition Details:

(1) Vendor & Product Description:



Product & Vulnerable Versions:


2.3 (2.3.9074.18820) 2.2 (2.2.8279.16125) 2.1(2.1.8102.813)

Vendor URL & download:

dasBlog can be obtained from here,

What is dasBlog?
"dasBlog Community Edition is an ASP.NET weblogging application. It runs on ASP.NET 1.1 and is developed in C#. dasBlog, an evolution of the BlogX weblog engine, adds lots of additional features like Trackback, Pingback, Mail notifications, full Blogger/M."

"This dasBlog 2.3.1 release comes almost 3 years since the release of dasBlog 2.3, we know this is an internet lifetime, and in many cases our user base may have moved on to other applications, (and/or are just checking back in to see what we have to offer, or you stuck with us and you may be outgrowing your current dasBlog installation! That said, if this is your first experience with dasBlog or you’re looking for improvements in your current dasBlog, you will find that dasBlog 2.3.1 is an incremental improvement, now supporting .NET 4 and resolving some minor support operations issues, and is even more robust and stable than it ever has been. What you will not find is a host of new features or much expansion of the existing features."

(2) Advisory Details:
Newtelligence dasBlog ct.ashx is vulnerable to Open Redirect attacks. Hacker can exploit it by Unvalidated Redirects and Forwards (Open Redirect or URL Redirection) attacks. This could allow a user to create a specially crafted URL, that if clicked, would redirect a victim from the intended legitimate web site to an arbitrary web site of the attacker's choosing. Such attacks are useful as the crafted URL initially appear to be a web page of a trusted site. This could be leveraged to direct an unsuspecting user to a web page containing attacks that target client side software such as a web browser or document rendering programs.

dasBlog supports a feature called Click-Through which basically tracks all links clicked inside your blog posts. It's a nice feature that allows the blogger to stay informed what kind of content readers like. If Click-Through is turned on, all URLs inside blog entries will be replaced with <URL to your blog>/ct.ashx?id=<Blog entry ID>&url=<URL-encoded original URL> which of course breaks WebSnapr previews.
 Web.config code:
<add verb="*" path="ct.ashx" type="newtelligence.DasBlog.Web.Services.ClickThroughHandler, newtelligence.DasBlog.Web.Services"/>

(2.1) The vulnerability occurs at "ct.ashx?" page, with "&url" parameter,.

(3) Solutions:
2014-10-15 Public disclosure with self-written patch.


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