Thursday, November 14, 2013

Volatility 2.3 and FireEye's diskless, memory-only Trojan.APT.9002

If you needed more any more evidence as to why your DFIR practice should evolve to a heavy focus on memory analysis, let me offer you some real impetus.
FireEye's Operation Ephemeral Hydra: IE Zero-Day Linked to DeputyDog Uses Diskless Method, posted 10 NOV 2013 is specific to an attack that "loaded the payload  directly into memory without first writing to disk." As such, this "will further complicate network defenders’ ability to triage compromised systems, using traditional forensics methods." Again, what is described is a malware sample (payload) that " does not write itself to disk, leaving little to no artifacts that can be used to identify infected endpoints." This FireEye analysis is obviously getting its share of attention, but folks are likely wondering "how the hell are we supposed to detect that on compromised systems?"
Question: Why does Volatility rule?
Answer: Because we don't need no stinking file system artifacts.
In preparation for a Memory Analysis with Volatility presentation I gave at SecureWorld Expo Seattle last evening, I had grabbed the malware sample described in great length by FireEye from VirusShare (MD5 104130d666ab3f640255140007f0b12d), executed it on a Windows 7 32-bit virtual machine, used DumpIt to grab memory, and imported the memory image to my SIFT 2.14 VM running Volatility 2.3 (had to upgrade as 2.2 is native to SIFT 2.14). 
I had intended to simply use a very contemporary issue (3 days old) to highlight some of the features  new to the just released stable Volatility 2.3, but what resulted was the realization that "hey, this is basically one of the only ways to analyze this sort of malware."
So here's the breakdown.
The FireEye article indicated that "this Trojan.APT.9002 variant connected to a command and control server at over port 443."
Copy that. Ran --profile=Win7SP1x86 -f WIN-L905IILDALU-20131111-234404.raw netscan and quickly spotted as seen in Figure 1.

Figure 1
 I was interested in putting timeliner through its paces as it is new to Volatility in 2.3, and was not disappointed. Issued --profile=Win7SP1x86 -f WIN-L905IILDALU-20131111-234404.raw timeliner --output=body --output-file=output.body and spotted in network connections tied closely to a timestamp of 1384212827? Er? That's Unix timestamp. Translated to human readable: Mon, 11 Nov 2013 23:33:47 GMT. Check! See Figure 2.

Figure 2

Clearly PID 3176 is interesting, keep it in mind as we proceed.
The article states that "after an initial XOR decoding of the payload with the key “0x9F”, an instance of rundll32.exe is launched and injected with the payload using CreateProcessA, OpenProcess, VirtualAlloc, WriteProcessMemory, and CreateRemoteThread."
Ok, so what is PID 3176 associated with? --profile=Win7SP1x86 -f WIN-L905IILDALU-20131111-234404.raw pslist | grep 3176 will tell us in Figure 3.

Figure 3
What, what?! It's rundll32.exe. Mmm-hmm.
Strings can help us for the next step to spot CreateProcessA, OpenProcess, VirtualAlloc, WriteProcessMemory, and CreateRemoteThread as associated with PID 3176. The Volatility wiki recommends using Sysinternals strings so we can use –q and –o switches to ensure that the header is not output (-q) and that there is an offset for each line (-o), as in strings -q -o WIN-L905IILDALU-20131111-234404.raw > strings.txt. We then convert strings.txt for Volatility with --profile=Win7SP1x86 -f WIN-L905IILDALU-20131111-234404.raw strings -s strings.txt --output-file=stringsVol.txt. Now we can search for strings that include 3176 and the likes of CreateProcessA, along with offsets to see if there are associations. A search immediately produced:
04cfce5a [3176:701f8e5a] CreateProcessA
abd60bd8 [3176:00191bd8] OpenProcess
abd60ae4 [3176:00191ae4] VirtualAlloc
bedd8384 [3176:10002384] WriteProcessMemory
bedd835a [3176:1000235a] CreateRemoteThread
What we've just validated is that PID 3176 (rundll32.exe) shows indications of the five functions described by FireEye.
 Per the article, "inside the in-memory version of the Trojan.APT.9002 payload used in this strategic Web compromise, we identified the following interesting string: “rat_UnInstall. Gotcha; a quick string search says: bd75bcc0 [3176:0035fcc0] __rat_UnInstall__3176.
The  rat_UnInstall IOC is clearly associated with PID 3176.

Just for giggles, I checked one last point made by FireEye. They stated that "we also found the following strings of interest present in these 9002 RAT samples (excluding the in-memory variant): McpRoXy.exe, SoundMax.dll
I was intrigued by the "excluding the in-memory variant claim", so I did I quick check. I could, as always, be wrong (tell me if I am), buy the dlllist module seems to disagree. --profile=Win7SP1x86 -f WIN-L905IILDALU-20131111-234404.raw dlllist -p 3176 | grep SoundMax.dll produced Figure 4.

Figure 4
When I checked the file system for C:\users\malman\SoundMax.dll, it was indeed present.
While I am operating on the belief that my analysis of  104130d666ab3f640255140007f0b12d matches the FireEye IOCs via Volatility memory analysis alone, dlllist does indicate that the malware drops SoundMax.dll on the file system. I attribute this to the possibility that my "delivery system" was different than the IE 0-day FireEye describes; I had to download the sample and execute it to replicate behavior.

Correction 15 NOV 2013: Ned Moran from FireEye contacted me to let me know that my assumption based on interpretation of the FireEye blogpost was incorrect. 104130d666ab3f640255140007f0b12d is not the diskless version of 9002; at this time FireEye is not providing hashes or sharing that sample at this time. I clearly misinterpreted their post to indicate that 104130d666ab3f640255140007f0b12d was that sample, I was incorrect and I apologize. That being said Ned assured me that I was not out of my mind and let me know "yes, my reading of your methodology is that it would have produced very similar results, the only difference being that had you would not have found the 'SoundMax.dll' string in the diskless version. So, your approach was sound you were just looking at a different sample."

Regardless, we wouldn't need any file system artifacts to confirm the presence of the diskless, memory-only version of Trojan.APT.9002 on a victim system.
Confirmed connection to with netscan: --profile=Win7SP1x86 -f WIN-L905IILDALU-20131111-234404.raw netscan 
Confirmed timeline for connection to with timeliner: --profile=Win7SP1x86 -f WIN-L905IILDALU-20131111-234404.raw timeliner --output=body --output-file=output.body
Identified rundll32.exe as owner of the suspect PID (3176) with pslist: --profile=Win7SP1x86 -f WIN-L905IILDALU-20131111-234404.raw pslist | grep 3176
Used strings as analysis to further confirm: --profile=Win7SP1x86 -f WIN-L905IILDALU-20131111-234404.raw strings -s strings.txt --output-file=stringsVol.txt 
Used dlllist to call out SoundMax.dll: --profile=Win7SP1x86 -f WIN-L905IILDALU-20131111-234404.raw dlllist -p 3176 | grep SoundMax.dll

One more time, with feeling: Why does Volatility rule? Hopefully, I've helped answer that...again.

Friday, November 01, 2013

toolsmith: OWASP Xenotix XSS Exploit Framework

Current Windows operating system

Hard to believe this month’s toolsmith marks seven full years of delivering dynamic content and covering timely topics on the perpetually changing threat-scape information security practitioners face every day. I’ve endeavored to aid in that process 94 straight months in a row, still enjoy writing toolsmith as much as I did day one, and look forward to many more to come. How better to roll into our eighth year than by zooming back to one of my favorite topics, cross-site scripting (XSS), with the OWASP Xenotix XSS Exploit Framework. I’d asked readers and Twitter followers to vote for November’s topic and Xenotix won by quite a majority. This was timely as I’ve also seen renewed interest in my Anatomy of an XSS Attack published in the ISSA Journal more than five years ago in June 2008. Hard to believe XSS vulnerabilities still prevail but according to WhiteHat Security’s May 2013 Statistics report:
1)      While no longer the most prevalent vulnerability, XSS is still #2 behind only Content Spoofing
2)      While 50% of XSS vulnerabilities were resolved, up from 48% in 2011, it still took an average of 227 for sites to deploy repairs
Per the 2013 OWASP Top 10, XSS is still #3 on the list. As such, good tools for assessing web applications for XSS vulnerabilities remain essential, and OWASP Xenotix XSS Exploit Framework fits the bill quite nicely.
Ajin Abraham (@ajinabraham) is Xenotix’s developer and project lead; his feedback on this project supports the ongoing need for XSS awareness and enhanced testing capabilities.
According to Ajin, most of the current pool of web application security tools still don't give XSS the full attention it deserves, an assertion he supports with their less than optimal detection rates and a high number of false positive. He has found that most of these tools use a payload database of about 70-150 payloads to scan for XSS. Most web application scanners, with the exception of few top notch proxies such as OWASP ZAP and Portswigger’s Burp Suite, don't provide much flexibility especially when dealing with headers and cookies. They typically have a predefined set of protocols or rules to follow and from a penetration tester’s perspective can be rather primitive. Overcoming some of these shortcomings is what led to the OWASP Xenotix XSS Exploit Framework.
Xenotix is a penetration testing tool developed exclusively to detect and exploit XSS vulnerabilities. Ajin claims that Xenotix is unique in that it is currently the only XSS vulnerability scanner with zero false positives. He attributes this to the fact that it uses live payload reflection-based XSS detection via its powerful triple browser rendering engines, including Trident, WebKit and Gecko. Xenotix apparently has the world's second largest XSS payload database, allowing effective XSS detection and WAF bypass. Xenotix is also more than a vulnerability scanner as it also includes offensive XSS exploitation and information gathering modules useful in generating proofs of concept.
For feature releases Ajin intends to implement additional elements such as an automated spider and an intelligent scanner that can choose payloads based on responses to increase efficiency and reduce overall scan time. He’s also working on an XSS payload inclusive of OSINT gathering which targets certain WAF's and web applications with specific payloads, as well as a better DOM scanner that works within the browser. Ajin welcomes support from the community. If you’re interested in the project and would like to contribute or develop, feel free to contact him via @ajinabraham, the OWASP Xenotix site, or the OpenSecurity site.

Xenotix Configuration

Xenotix installs really easily. Download the latest package (4.5 as this is written), unpack the RAR file, and execute Xenotix XSS Exploit Framework.exe. Keep in mind that antimalware/antivirus on Windows systems will detect xdrive.jar as a Trojan Downloader. Because that’s what it is. ;-) This is an enumeration and exploitation tool after all. Before you begin, watch Ajin’s YouTube video regarding Xenotix 4.5 usage. There is no written documentation for this tool so the video is very helpful. There are additional videos for older editions that you may find useful as well. After installation, before you do anything else, click Settings, then Configure Server, check the Semi Persistent Hook box, then click Start. This will allow you to conduct information gathering and exploitation against victims once you’ve hooked them.
Xenotix utilizes the Trident engine (Internet Explorer 7), the Webkit engine (Chrome 25), and the Gecko engine (Firefox 18), and includes three primary module sets: Scanner, Information Gathering, and XSS Exploitation as seen in Figure 1.

FIGURE 1: The Xenotix user interface
We’ll walk through examples of each below while taking advantage of intentional XSS vulnerabilities in the latest release of OWASPMutillidae II: Web Pwn in Mass Production. We covered Jeremy Druin’s (@webpwnized) Mutillidae in August 2012’s toolsmith and it’s only gotten better since.

Xenotix Usage

These steps assume you’ve installed Mutillidae II somewhere, ideally on a virtual machine, and are prepared to experiment as we walk through Xenotix here.
Let’s begin with the Scanner modules. Using Mutillidae’s DNS Lookup under OWASP Top 10 à A2 Cross Site Scripting (XSS) à Reflected (First Order) à DNS Lookup. The vulnerable GET parameter is page and on POST is target_host. Keep in mind that as Xenotix will confirm vulnerabilities across all three engines, you’ll be hard pressed to manage output, particularly if you run in Auto Mode; there is no real reporting function with this tool at this time. I therefore suggest testing in Manual Mode. This allows you to step through each payload and as seen Figure 2, we get our first hit with payload 7 (of 1530).

FIGURE 2: Xenotix manual XSS scanning
You can also try the XSS Fuzzer where you replace parameter values with a marker, [X], and fuzz in Auto Mode. The XSS Fuzzer allows you to skip ahead to a specific payload if you know the payload position index. Circling back to the above mentioned POST parameter, I used the POST Request Scanner to build a request, establishing as the URL and setting target_host in Parameters. Clicking POST then populated the form as noted in Figure 3 and as with Manual mode, our first hits came with payload 7.
FIGURE 3: Xenotix POST Request Scanner
You can also make use of Auto Mode, as well as DOM, Multiple Parameter, and Header Scanners, as well as a Hidden Parameter Detector.

The Information Gathering modules are where we can really start to have fun with Xenotix. You first have to hook a victim browser to make use of this tool set. I set the Xenotix server to the host IP where Xenotix was running (rather than the default localhost setting) and checked the Semi Persistent Hook checkbox. The resulting payload of
was then used with Mutillidae’s Pen Test Tool Lookup to hook a victim browser on a different system running Firefox on Windows 8.1. With the browser at my beck and call, I clicked Information Gathering where the Victim Fingerprinting module produced:
Again, entirely accurate. The Information Gathering modules also include WAF Fingerprinting, as well as Ping, Port, and Internal Network Scans. Remember that, as is inherent to its very nature, these scans occur in the context of the victimized browser’s system as a function of cross-site scripting.

Saving the most fun for last, let’s pwn this this thang! A quick click of XSS Exploitation offers us a plethora of module options. Remember, the victim browser is still hooked (xooked) via:
I sent my victim browser a message as depicted in Figure 4 where I snapped the Send Message configuration and the result in the hooked browser.

FIGURE 4: A celebratory XSS message
Message boxes are cute, Tabnabbing is pretty darned cool, but what does real exploitation look like? I first fired up the Phisher module with Renren (the Chinese Facebook) as my target site, resulting in a Page Fetched and Injected message and Renren ready for login in the victim browser as evident in Figure 5. Note that my Xenotix server IP address is the destination IP in the URL window.

FIGURE 5: XSS phishing Renren
But wait, there’s more. When the victim user logs in, assuming I’m also running the Keylogger module, yep, you guessed it. Figure 6 includes keys logged.

FIGURE 6: Ima Owned is keylogged
Your Renren is my Renren. What? Credential theft is not enough for you? You want to deliver an executable binary? Xenotix includes a safe, handy sample.exe to prove your point during demos for clients and/or decision makers. Still not convinced? Need shell? You can choose from JavaScript, Reverse HTTP, and System Shell Access. My favorite, as shared in Figure 7, is reverse shell via a Firefox bootstrapped add-on as delivered by XSS Exploitation --> System Shell Access --> Firefox Add-on Reverse Shell. Just Start Listener, then Inject (assumes a hooked browser).

FIGURE 7: Got shell?
Assuming the victim happily accepts the add-on installation request (nothing a little social engineering can’t solve), you’ll have system level access. This makes pentesters very happy. There are even persistence options via Firefox add-ons, more fun than a frog in a glass of milk.

In Conclusion

While this tool won’t replace proxy scanning platforms such as Burp or ZAP, it will enhance them most righteously. Xenotix is GREAT for enumeration, information gathering, and most of all, exploitation. Without question add the OWASP Xenotix XSS Exploit Framework to your arsenal and as always, have fun but be safe. Great work, Ajin, looking forward to more, and thanks to the voters who selected Xenotix for this month’s topic. If you have comments, follow me on Twitter via @holisticinfosec or email if you have questions via russ at holisticinfosec dot org.
Cheers…until next month.


Ajin Abraham, Information Security Enthusiast and Xenotix project lead