Linkz about Attacks

Sunday, October 16, 2011 Posted by Corey Harrell
In this round of links I’m talking about drive-bys, malicious ads, web attack artifacts revealed with Mandiant’s Highlighter, and a justification for companies to fail security audits.

Video Showing Drive-by Download from MySQL

As most people probably heard by now was serving up malware to its visitors last month. SecurityMonkey put together the post [Video]: Watch Malware Drive-By Download from which contained various links about the incident. One link was to a video created by Armorize that captured what happened to anyone who visited the website when the issue was occurring. The video is about five minutes long and I highly recommend for people to check it out. I’ve never seen a drive-by broken down before by video. The video by itself is pretty cool but I think the true value is in what it shows about the attack vector infecting people visiting the website. Check out the sequence of events I noted from the video:

        -  (00:55) Internet Explorer starts to load the website
        -  (01:04) Java.exe starts running on the computer
        -  (01:11) Executables are dropped onto the computer. These were the attack’s payload
        -  (03:43) It was revealed that a Jar file was downloaded to the system and this is why Java started. The Jar file download occurred before the executables appeared on the computer

The attack summary was a user visited and eventually gets redirected to a site hosting the Black Hole exploit pack. In that instance, the exploit pack used a Java vulnerability to infect the system. Why does any of this even matter … knowing this can help determine how a system was compromised. Let’s say someone was dealing with an infected computer and were trying to figure out how the malware got installed on the computer. The video didn’t show what was on the system’s hard drive but the attack is very similar to the Java exploit artifacts I documented. To date I’ve documented three different ones which were Java Signed Applet Exploit Artifacts, CVE-2010-0840 (Trusted Methods) Exploit Artifacts, and CVE-2010-0094 (RMIConnectionImpl) Exploit Artifacts. There was a consistent pattern to the all the artifacts:

        -  Temporary file created (Jar file got dropped onto the system)
        -  Indications of a vulnerable Java executing
        -  Internet activity showed a user visited a malicious website

The key difference (besides the Java vulnerability) between the Armorize video and the method I used to document the exploit artifacts was the tool used to create and deliver the exploit. The video documented a Java exploit from the Blackhole exploit pack and according to Contagio’s August 2011 Exploit Pack Overview spreadsheet Blackhole goes for $1,500 a year. My testing leveraged the freely available Metasploit to document exploit artifacts. Taking the time to document the exploit artifacts can pay big dividends during an examination when trying to determine the “how”. How did the system get infected? Well if the activity on the system around the time malware was created shows either a Jar file appearing or Java executing then a Java vulnerability may have been the culprit. If there is Internet activity then the Internet and a web browser may have been used to deliver the exploit to the system.

Malicious Advertisement Leads to PDF Exploit

I first started looking into attack vector artifacts when one of my systems got whacked with a Fake AV virus. At the time I had the DF skills but I lacked the IR skills such as figuring out what happened to my system. I took a shot at trying to figure out how the system became infected to see if I could. It took me a little bit but I was not only able to find the malware dropped onto my system but I traced the infection back to Yahoo email. I was even able to determine the exploit used in the drive-by. It was a malicious PDF file that targeted a vulnerability in Adobe Reader. The PDF appeared on the system in the temporary Internet files folder just prior to the first malware getting dropped. The experience taught me valuable lessons. First the more obvious one; don’t quickly check your web email from a test system with vulnerable apps even if it’s only for a few seconds. The second and more important lesson was the need to understand how different attacks appear on a system after they have occurred. The examination took me some time to figure out since I didn’t really know what to expect or what artifacts to look for.

I recently came across TrendMicro’s post Malicious Ads Lead to PDF Exploits. The post is from last year but it made me reflect on the experience that motivated me to start my journey into incident response. The post mentioned how malvertisements on a popular web-based email service lead to users being directed to sites with exploits. The article isn’t written from the DFIR perspective since it was focused on the vulnerabilities targeted in the attack. There wasn’t much discussion about the artifacts left on a system either besides malicious PDFs and internet activity. The little information provided did show how the attack occurred.

        -  User visits web based email service
        -  Redirect downloads malicious PDFs targeting Adobe Reader vulnerabilities
        -  Adobe reader has to process the PDF for the exploit to be successful and install malware

The attack pattern is something I’ve seen in a few other places. My infected test system had the same sequence of events but it took me a bit to actually see it. That examination made me more aware about the artifacts associated with a PDF exploit thereby making it easier to spot it in a few other examinations I did afterwards. I also saw the same pattern on my test systems I exploited with Metasploit. I researched a PDF exploit in the post CVE-2010-2883 (PDF Cooltype) Exploit Artifacts. Do the following areas I noted in the post look familiar?

        -  PDF document created
        -  There were references about a PDF file being accessed
        -  A vulnerable Adobe Reader started on the system

Web Attack Artifacts

Russ McRee’s October’s Toolsmith Log Analysis with Highlighter is a great read for a couple reasons. I enjoy reading his articles since he provides an overview about a tool’s functionality. In this edition he doesn’t disappoint as he covers how to perform log analysis with Mandiant’s Highlighter. Showing how to do log analysis is cool enough but he demonstrates the tool by looking for attacks in his website’s logs. He looks for specific artifacts caused by remote file include and directory traversal attacks. I haven’t found any references that document the artifacts left in logs by different attacks so I enjoyed reading about it. Eventually I’m going to start researching the artifacts left in logs but I still have a lot to do with the artifacts left on systems.

Fail a Security Audit Already Will You

When I started working full time in the information security field I was performing vulnerability assessments and security audits. Maybe I’m a little biased because of my background but I can see the value security audits provide when performed correctly. I’m not talking about audits where boxes are just checked off but risk based audits looking at the security controls protecting an organization’s critical information. Andreas M. Antonopoulos's article Fail a security audit already -- it's good for you provides an argument for why companies should fail security audits. The article makes some great points but the one thing I thought was missing is when organizations try to justify (aka make excuses) or minimize why serious weaknesses are present. Take patching as an example.

Patching isn’t done to prevent applications and systems from breaking. I was a system admin so I get it … especially since I’ve dealt with the hassle of tracking down the patches that jacked up my systems. However, using the reason as a justification to not patch without doing any due diligence by you know actually testing patches to see if anything breaks is something else. The SANs Top Cyber Security Risks report from a few years ago highlighted how third party applications on client systems are targeted. The exploits I discussed in this linkz edition targeted vulnerabilities in client applications such as Java and Adobe. How can these vulnerabilities on computers with users surfing the web be lumped into the same category as some application supporting a critical business process with neither of them getting patched? The security risk didn’t go away and the vulnerabilities don’t magically repair themselves. It’s too late to finally figure it out once the organization is staring at the artifacts from a successful exploit.

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