Category: Malware

Hey folks,

Happy New Year, and welcome to 2014!

On a recent trip to Tyson’s Corner, VA, I had some time to kill, so I took a careful look at a malware sample that a friend of mine sent to me some time ago, which I believe he originally got off somebody else’s hosed system. The plan was for me to investigate it, and I promised him I would; it just took awhile!

Anyways, the sample has a few layers of packing, and I thought it’d be fun/interesting to show you how to unwrap the entire thing to obtain the final payload. I am not going to discuss the payload itself in this post, largely because I haven’t spent much time reversing it. Perhaps in the future I’ll dig a little deeper, but for now we’ll focus on the packing.

I called this sample “lcmw”. It stood for something interesting, but I don’t really remember what—I may have been drinking when I named it. :)

Now that we know what we need to send and receive, and how it’s encoded, let’s generate the actual packet. Then, once we’re sure it’s working, we’ll convert it into an Nmap probe! In most of this section, I assume you’re running Linux, Mac, or some other operating system with a built-in compiler and useful tools (gcc, hexdump, etc). If you’re on Windows, you’ll probably just have to follow along until I generate the probe.

In Part 2: runtime analysis, we discovered some important addresses in the Energizer Trojan – specifically, the addresses that make the call to recv() data. Be sure to read that section before reading this one.

Now that we have some starting addresses, we can move on to a disassembler and look at what the code’s actually doing. Fortunately, the author made no attempt to disguise the code or pack or or anything like that, so a simple disassembler is all we need to examine the code.

A word of warning: this is the longest, most complicated section. But stick with it, by the end we’ll know exactly how the Trojan ticks!

In Part 1: setup, we infected the system with the Trojan. It should still be running on the victim machine. If you haven’t read that section, I strongly recommend you go back and read it.

Now that we’ve infected a test machine, the goal of this step is to experiment a little with the debugger and learn a little about the Energizer Trojan. This can all be discovered with a simple disassembler, but I find it more fun to take apart a live sample. All we’re going to do is add a breakpoint at the recv() function and see where it’s called from.

This step is going to require Debugging Tools for Windows. If you haven’t installed it already, install it on the victim machine.

Hey all,

As most of you know, a Trojan was recently discovered in the software for Energizer’s USB battery charger. Following its release, I wrote an Nmap probe to detect the Trojan and HDMoore wrote a Metasploit module to exploit it.

I mentioned in my last post that it was a nice sample to study and learn from. The author made absolutely no attempt to conceal its purpose, once installed, besides a weak XOR encoding for communication. Some conspiracy theorists even think this may have been legitimate management software gone wrong – and who knows, really? In any case, I offered to write a tutorial on how I wrote the Nmap probe, and had a lot of positive feedback, so here it is!

Just be sure to take this for what it is. This is not intended to show any new methods or techniques or anything like that. It’s a reverse engineering guide targeted, as much as I could, for people who’ve never opened IDA or Windbg in their lives. I’d love to hear your comments!

Hey,

I don’t usually write two posts in one day, but today is a special occasion! I was reading my news feeds (well, my co-op student (ie, intern) was – I was doing paperwork), and noticed a story about a remote backdoor being included with the Energizer UsbCharger software</a>. Too funny!

Greetings!

I found this excellent writeup of a Web-server botnet on Slashdot this weekend. Since it sounded like just the thing for Nmap to detect, I wrote a quick script!

Hi everybody,

With the help of Symantec’s Security Intelligence Analysis Team, I’ve put together a script that’ll detect Conficker (.C and up) based on its peer to peer ports. The script is called p2p-conficker.nse, and automatically runs against any Windows system when scripts are being used:

nmap --script p2p-conficker,smb-os-discovery,smb-check-vulns \
        --script-args=safe=1 -T4 -p445 <host>
or
sudo nmap -sU -sS --script p2p-conficker,smb-os-discovery,smb-check-vulns \
        --script-args=safe=1 -T4 -p U:137,T:139 <host>

See below for more information!

Or, if you just want to scan your network fast, give this a shot:

nmap -p139,445 --script p2p-conficker,smb-os-discovery,smb-check-vulns \
        --script-args=checkconficker=1,safe=1 -T4 <host>

• Official Nmap announcement
• Official Symantec announcement

Morning, all!

Last night Fyodor and crew rolled out Nmap 4.85beta7. This was because some folks from the Honeynet Project discovered a false negative (showed no infection where an infection was present), which was then confirmed by Tenable. We decided to be on the safe side, and updated our checks.

Using Nmap to scan for the famous Conficker worm.