Zemra DDoS Bot: Backdoors in your Backdoors!

So, ailment today I grabbed a sample of the leaked “Zemra” botnet source code, and quickly did a “10 second analysis” of the webpanels source code. I often do this to see can I locate any “GLARING SECURITY FLAWS” in the C&C. I am also working on finding a google-dork to find Zemra installations.

For information about Zemra the following links are useful :)



So. This was on sale in various places online (Russian forums apparently), here however I suspect (based on the backdoor and the fact it is written in C#) that is is German in origin. Some of the stuff in there seems to be German also, illness so I assume it is another product of the German Skid Scene. Basically “Rippers Inc”. LAME!

Anyway, I was looking at the webpanels source (I will eventually rip the bots source apart) and noticed that gate.php has some lulzy SQLi (possibly).

Far more interesting was the backdoor. Located at /Zemra/Panel/Zemra/system/command.php, it is your basic “BACKDOOR”. It takes the GET parameter “cmd” and executes it.

Example: localhost/Zemra/Panel/Zemra/system/command.php?cmd=cat /etc/passwd

I will be researching this in greater depth… Sometime in the near-ish future. But as always, there be backdoors in your backdoors!

Finally: Zemra.rar file is here: Zemra

Hydra IRC bot, the 25 minute overview of the kit.

Hydra IRC bot, the 25 minute overview of the kit. (25 minutes to write and “do”, not to read!)

The Hydra IRC botnet kit is a very interesting sample that we have in our collection. It is, essentially, “RX-Bot for Routers”. By this, we mean it is an extensible, well documented (in the source), open source botnet framework which is freely available for anyone to download. The problem, of course, is locating a copy.

Unlike other IRC bots targetting the “Linux” platform, for example, the “Kaiten” series of bots written in C, or the “ShellBot” series of bots written in various scripting languages, the Hydra is a more carefully developed framework, and by design is far more extensible than the others.

While the Kaiten family offer potent DDoS capabilities, they totally lack spreading tools – in order to “spread” a Kaiten effectively, you would have to root Linux servers en-masse. The Hydra, has built in worm-like capabilities, allowing it to automatically seek out and infect new victims.

The shellbots DO spread, and may even infect other platforms/architectures (being written in scripting languages means they will run on anything that has an interpreter), however their DDoS capabilities are weak, and they tend to be rather “hacky” programs.

Furthermore, while the Kaiten bots are almost limited to the x86-Linux platform (they stubbornly refuse to compile on much else), the Hydra series is designed to run on damn near anything – in particular, MIPSEL routers.

Most interesting of all, however, is the fact that the development of these elegant pieces of malware has not progressed much. Wheras the Kaiten and Shellbot are constantly being remade, the Hydra, being a far more impressive – and complex – piece of code, is pretty much ignored by your contemporary developer of Unix malware. This is unusual, as its counterpart on Windows – RXbot, was developed almost religiously.

Anyways, on we go. Lets crack open the archive and see what is inside!

Contents of the Archive:
infodox@shinigami:~/router/hydra$ ls -R
ChangeLog – Changelog for this version.
include – Directory of header files.
Makefile – Makefile.
README – Readme.
source – Main source code files.

hydra_conf.h – Bot configuration header file.
hydra_irc.h – IRC header file.
hydra_mesg.h – Messages it prints to channel for various purposes.
hydra_scan.h – Variables used in vulnerability scanning/exploitation.
hydra_utils.h – Currently just a variable to assign to process ID for daemonizing.
hydra_hds.h – File containing list of header files.
hydra_main.h – Just some variables.
hydra_reqs.h – More variables, version number, etc.
hydra_synf.h – Headers/Variables for SYN Flooding.

hydra_irc.c – IRC handling code.
hydra_reqs.c – Command parsing code apparently.
hydra_synf.c – SYN Flooding/DDoS Functions.
hydra_main.c – main() function.
hydra_scan.c – Scanning functions for owning routers.
hydra_utils.c – Functions used for daemonizing, host2ip, etc. “Utilities”.

As you can see, it is a fairly well-crafted piece of software, in that the developers did not try jam everything in one source file, like the developers of Kaiten and the ShellBots do. Instead, everything is split up rather neatly. This would make future development FAR easier than hacking on one file!

So, lets take a look at what version we got, and its changelog!

– Begin Changelog –

Hydra 2008.1 stable (released 2008-02-23)

* added input line parser.
* added irc connection random ident string.
* added source address synflood spoofing.
* added daemonize manage function for quiet debug
* fixed ‘upgrade’ same file replace bug.
* fixed serveral error messages.
* removed an command ‘reclst’ for unutility.
* source code completly rewrite.

– End Changelog –

So, it would seem that this was the “first release of 2008”. And the changelog itself makes me think the developer was doing some serious work on it – rewriting the source code completely, fixing bugs, removing useless functions and commands… It makes me wonder were there previous variants that I have simply not obtained yet.

Onward we go to the Makefile, and for brevity I only include the relevant snippet here – the rest is pretty much “normal”.

– Begin Makefile Snippet –


– End Makefile Snippet –

So, we can clearly see, this version supports the MIPSEL and x86 architectures, and I do wonder who “hardhat” is… Don’t you?

The fact the author wrote a somewhat decent makefile suggests either an IDE of some kind that auto-generates them for you, or, a somewhat competent author. Having had difficulty getting ANYTHING to run on MIPSEL routers in the past, I will go with “competent”.

Lets take a look at the readme, see if we can gather more data! As @TheResGroup says, “we love data”.

First off, the author is not a native English speaker. Second, his email is proudly on display as “esaltato@autistici.org”. I checked autistici.org, it seems to be some kind of Privacy collective, similar to Riseup.net (who, by the way, are AWESOME). It also makes me think of Italy, and there is more evidence for this later on when we see the predefined C&C server.

In the readme, he describes his program in the following manner:
“Hydra is a mass-tool commanded by irc that allows scanners and exploited dlink router for make BOTNET (rx-bot style), in addition to this, with void you can attack with tcp/udp flood.”
Ok, so we know his intention – an RX Bot style bot for routers, in particular, D-Link routers. Now, unless I am terribly mistaken, the D-Link routers run DD-WRT of some kind, which is basically MIPSEL Linux. Which is why this bot works so damn well.

The interesting thing is, he does NOT give a command list in the readme! So the user could setup their botnet, then realize they have NO clue how to use it!

So, lets go find the commands, and figure out what they do!

By opening source/hydra_main.c we get the following:

– Begin Hydra Command List –

* *** Access Commands:
* .login <password> – login to bot’s party-line
* .logout – logout from bot’s party-line
* *** Misc Commands
* .upgrade <url> <binary_name> – upgrade binary from http url
* .version – show the current version of bot
* .status – show the status of bot
* .help – show this help message
* *** Scan Commands
* .scan <a> <b> <user> <passwd> – scanner/exploit with user:passwd
* .advscan <a> <b> – scanner/exploit with auto user:passwd
* .recursive – scanner/exploit with localip scan
* .recrd – advscan with local addr (B-range random)
* .stop – stop all actions (scan/flood)
* *** DDOS Commands:
* .synflood <host> <port> <secs> – standard synflooder
* *** IRC Commands:
* .join <channel> <password> – join bot in selected room
* .part <channel> – part bot from selected room
* .quit – kill the current process

– End Hydra Command List –

So. While the README tells us we have both UDP/SYN flooding, the commands only offer SYN. Which makes me assume we are missing some commands! Having poked through the source, the UDP flooding functionality is simply not there, so I assume it is not implemented in this version.

Now that we have an overview of the bots capabilities, let’s take a look at the DDoS code in it, before I wrap this post up. Please note – this post is essentially a “teaser” of a paper me and a fellow researcher are writing on this kind of malware, and trust me – that paper is gonna be badass.

– Begin TCP Packet Creation Snippet – source/hydra_synf.c –

/* form tcp packet */
send_tcp.tcp.source = getpid();
send_tcp.tcp.dest = htons(dest_port);
send_tcp.tcp.seq = getpid();
send_tcp.tcp.ack_seq = 0;
send_tcp.tcp.res1 = 0;
send_tcp.tcp.doff = 5;
send_tcp.tcp.fin = 0;
send_tcp.tcp.syn = 1;
send_tcp.tcp.rst = 0;
send_tcp.tcp.psh = 0;
send_tcp.tcp.ack = 0;
send_tcp.tcp.urg = 0;
send_tcp.tcp.window = htons(512);
send_tcp.tcp.check = 0;
send_tcp.tcp.urg_ptr = 0;

– End TCP Packet Creation Snippet – source/hydra_synf.c –

As we can see, it is sending a SYN packet, with a window size of 512, to a specified port. It uses its PID as the sequence number and has an offset of 5. Surely a detection could be written, but I am sure it would be littered with false positives.

Now, I am not an expert, but the following snippet makes me think maybe it is threading the function to run 50 times – I do not see any calls to fork(), but it seems to have a loop here that increments a counter (vt) every time a thread runs.

– Begin Threading Snippet –

if (vt >= 50)
if (time(NULL) >= start + ntime)
arg_send(sp->s_fd, end_synflood, irc_room);


vt = true;


– End Threading Snippet –

It would appear that this snippet runs a counter, which SYN floods with 50 threads for X time, and alerts the IRC room when it is done. Fairly standard fare for an IRC bot, however most thread numbers I see are 64/128/256 in other bots/DDoS tools. Likely they use less threads due to the limited CPU capabilities of embedded devices, or, maybe the programmer just wanted to use 50 threads…

This concludes my “brief writeup” on the Hydra, and in an upcoming paper I will be covering it in more depth – including its propagation mechanisms and other interesting things that we find, including the hardcoded C&C, configuration settings, and such.

Hope you enjoyed :)

Malware.lu vs Herpesnet Botnet

Recently, a group of malware researchers, at Malware.lu – have seemingly taken the fight back against botnets another step.

Now, first off, let’s get my position on this straight for those watching me who are just waiting for me to break some kind of law or ethical barrier: While I wholeheartedly support these researchers actions, and believe that their approach to “dealing with botmasters” is the way forward, I will NOT be participating in it without cooperation of some sort from Law Enforcement, or legal permission to do so. The ice under my feet is too fucking thin to go popping C&C servers, though I wish I could.

The reason why we should take the fight back to the botnet masters is simple: They have the upper hand here. We do not. They can simply keep changing their C&C servers, keep doing DNS switcharoos, and keep spreading their malware, targeting innocent bystanders and making off with reams of personal data, while us researchers can do shag all except report to the authorities and pray to god they do something. It is not until someone like Microsoft gets involved that shit ACTUALLY gets done.

If the relevant authorities would issue “carte blanche”, or even a “carte gris” to take down botnets if the opportunity arises, the internet would be a far safer place. Until PROACTIVE measures are taken to make the cost of operating and owning these things too damn high for the amateurs, the smaller botnets will proliferate undetected for infinite time.

Anyways, on to the story.

So, the guys at malware.lu (I believe it was r00tBSD) got a sample in, of the HerpesNet botnet. I had been investigating Herpesnet for a while, after seeing it offered up as a “botnet as a service” type thing. You simply infect people, the botmaster/owner handles the C&C and backend server, along with writing the malware.

Fascinating system, and it is criminal economies like these that need to be stamped out. This particular sample was proliferating on Skript Kiddie forums predominantly, however, it is simply showing how *Fast* this kind of service offering has become common place.

Upon analysing the unpacked (non obfusticated) binary, and decrypting the few strings that were obscured, they were able to locate its C&C server.

They were also able to uncover what it sent to the server in HTTP POST requests, which seemingly, was sent in plaintext, and therefore offered them insights into what kind of data this thing was stealing, etc.

The researchers then decided to see could they perhaps use SQL injection attacks to own the command and control server, and in the end, they succeeded, gaining access to the administrator (botmasters) account on the C&C.

Taking things further, they actually uploaded a Meterpreter payload to the server and ran it, remotely hijacking the C&C. They took a screenshot of the C&C through the Meterpreter shell, and it LOOKS to me like it was the malware authors own box they had owned.

Pretty stupid, hosting a multi user botnet on your own box… But… Criminals are rarely the most intelligent it seems.

Now for the REALLY fun part: They then dumped the bots source code, etc. onto their box for more analysis, and subsequently the botmaster severed the box’s internet connection.

Not only this… They doxed the botmaster! Revealing his true identity for all to see (and for all to arrest…).

This kind of thing could be seen by some as vigilante justice, however, I see it as the future of the fight back against crimeware and online fraud. Even xylitol seems to get away with this, so my question to you all is as follows: What is the ethics/legality to this? CAN I legally start “assisting” LEO by dropping botnets and doxing their owners? I am FAIRLY sure I would be breaking anti-hacking laws, but, I also know the law pretty much requires me to do my duty as a citizen to PREVENT crime.

While I won’t be popping botnet C&C servers anytime soon, it is an interesting question to ask… And one I would love to know the answer to.

For more on this story, check out the article the guys wrote here:
Herpesnet Analysis and Ownage – Malware.lu

And also check out their main site: http://malware.lu

Massive props to the Malware.lu team, they are REAL internet superheros!