1. OVERVIEW

The Nitro PDF Reader application is vulnerable to Insecure DLL
Hijacking Vulnerability. Similar terms that describe this
vulnerability have been come up with Remote Binary Planting, and
Insecure DLL Loading/Injection/Hijacking/Preloading.


2. PRODUCT DESCRIPTION

Nitro's new free PDF reader takes the key features that you want in a
PDF reader, a familiar interface, and smooth functionality and
combines them into an eminently usable program that doesn't get in
between you and your documents. Nitro has turned the free PDF
alternative business model on its ear by providing you with a smart
selection of watermark-free editing, drag-and-drop PDF creation, and
tabbed PDF reading.


3. VULNERABILITY DESCRIPTION

The Nitro PDF Reader application passes an insufficiently qualified
path in loading its external libraries -  "dwmapi.dll,  nprender.dll"
when a user opens its associated file with extensions - fdf, pdf .
(N.B. first launch with nprender.dll may not be successful. CPU Usage
might jump up. Kill the application. Reopen the pdf and DLL Poup
message will be seen)


4. VERSIONS AFFECTED

2.5.1 and probably lower versions


5. PROOF-OF-CONCEPT/EXPLOIT

http://core.yehg.net/lab/pr0js/advisories/dll_hijacking/nitro_pdf_reader/poc/movie/nitro_pdf-1.2.0.11_dll-hijacking.mp4
http://core.yehg.net/lab/pr0js/advisories/dll_hijacking/nitro_pdf_reader/poc/nitro_pdf-1.2.0.11_dll-hijacking-poc.zip

Tested Platform: Windows XP Service Pack 3 (Fresh Windows)


6. IMPACT

Attackers can trigger a successful exploit against a victim user in a
number of ways such as placing a malicious external
library file made as hidden attribute and a seemingly interesting file
in network shares, usb drives, file sharing networks,
social networks, ..etc	


7. SOLUTION

Fixed version from the vendor has not been released yet.
However, it is suggested that the following workarounds be deployed by
users to protect increasing mass exploitation of this
vulnerability class:
- Disable loading of libraries from WebDAV and remote network shares
- Disable the WebClient service
Please see workaround solution links in References section.


8. VENDOR

Nitro PDF Pty Ltd
http://www.nitropdf.com/


9. CREDIT

This vulnerability was discovered by Aung Khant, http://yehg.net, YGN
Ethical Hacker Group, Myanmar.


10. DISCLOSURE TIME-LINE

09-09-2010: notified vendor
09-13-2010: vulnerability disclosed


11. REFERENCES

Original Advisory URL:
http://core.yehg.net/lab/pr0js/advisories/dll_hijacking/[nitro_pdf_reader]_2.5.1_insecure_dll_hijacking
Workaround Solution: http://support.microsoft.com/kb/2264107
Workaround Solution:
https://www.microsoft.com/technet/security/advisory/2269637.mspx#EGF
Developer Solution:
http://msdn.microsoft.com/en-us/library/ff919712%28v=VS.85%29.aspx
Unofficial DLL Hijacking List:
http://www.corelan.be:8800/index.php/2010/08/25/dll-hijacking-kb-2269637-the-unofficial-list/
Testing for DLL Hijacking:
http://core.yehg.net/lab/pr0js/view.php/when_testing_for_dll_hijacking.txt

#yehg [09-13-2010]

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