Botnet Targets Web Sites With Junk SSL Connections 64
angry tapir writes "More than 300 Web sites are being pestered by infected computers that are part of the Pushdo botnet. The FBI, Twitter, and PayPal are among the sites being hit, although it doesn't appear the attacks are designed to knock the sites offline. Pushdo appears to have been recently updated to cause computers infected with it to make SSL connections to various Web sites — the bots start to create an SSL connection, disconnect, and then repeat." SecureWorks's Joe Stewart theorizes that this behavior is designed to obscure Pushdo's command and control in a flurry of bogus SSL traffic.
Re: (Score:2, Insightful)
It sounds like some pretty old fashion DoS/DDoS attacks. What's so fancy about initiating multiple requests, and leaving them hanging? Folks have been tuning up their http servers to handle this for years. Why can't they tune up their https side too, other than the admins being lazy or inept?
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Re:nginx to the rescue? (Score:5, Insightful)
Not really.
I've had to parse logs for similar things. Thousands of requests hit a particular exploitable web page, but only one or two IP's are sending further information. It's easy to trim it down the list of candidates, and find who the real problem is.
That's what the feds do in any investigation. They have a broad list of suspects. They eliminate folks until they have their persons of interest, and then down to the guy who they'll be convicting.
ftfy (Score:1, Insightful)
Not really.
I've had to parse logs for similar things. Thousands of requests hit a particular exploitable web page, but only one or two IP's are sending further information. It's easy to trim it down the list of candidates, and find who the real problem is.
That's what the feds do in any investigation. They have a broad list of suspects. They eliminate folks until they have their persons of interest, and then down to the guy who they'll be charging.
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Ideally, if they have all the evidence, and they did their jobs right (proper investigative techniques, properly mirandizing the suspect(s), properly requesting subpoenas, and proper handling of the evidence), it will lead to a conviction. I was just leaving out all that pesky middle dialogue. I skipped over plenty of other steps too.
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It's a fairly important distinction though that it's a jury of peers who do the convicting, not the feds.
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Well, the feds decide who to prosecute, therefore who they intend to get a conviction against. It usually isn't "Lets charge a bunch of people, and see who we can get a conviction on." At least for a real investigative organization. For folks like the RIAA, they do the blanket "lets sue everyone, and let the courts sort them out" method. The RIAA is not a federal nor law enforcement agency, nor are they looking for a conviction, just a judgement against someone (or everyone).
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You're right, and you're not quite right. Sit in any courtroom in America, and watch the proceedings for a day or six. Many, many people WAIVE their rights to a trial by jury, and accept a plea bargain.
In some cases - that's bad, because the guy is not guilty, but is either intimidated into accepting the plea, or just can't afford good representation.
In a lot more cases, it's bad, because real dirt bags get sweet deals, and they'll be back on the streets real soon, victimizing more people.
Some cases, I gu
From TFA (Score:1)
The strange traffic targeting the Web sites--including sites for the CIA, FBI, PayPal, Yahoo, and Twitter, according to a list at the Shadow Server Foundation--was not enough to cause any outages or slowdowns, said Joe Stewart, director of malware research at SecureWorks.
So this isn't a really big deal. I'm almost tempted to praise the botnet creators for coming up with a good solution to obscuring the command and control issue. It is a good solution to a difficult problem. (Good here being used in the sense of good solution to a puzzle or engineering problem)
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Good here being used in the sense of good solution to a puzzle or engineering problem
Don't worry. If it doesn't have anything to do with patent laws or copyright, most Slashdotters have fairly lax moral standards. Especially when it comes to computers.
Re:From TFA (Score:4, Funny)
most Slashdotters have fairly lax moral standards. Especially when it comes to computers.
Yes, essentially we are all evil . . . now where's that kitten? Er, sorry, I meant robotic, remote-controllable kitten with embedded linux firmware!?
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Moral standards? What are those? God, I hate obscure standards!!
Oh, wait - didn't Microsoft Embrace, Extend, and Extinguish moral standards years back? It's hard to remember . . .
Re:From TFA (Score:4, Insightful)
Re:From TFA (Score:5, Informative)
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Dude, like maybe it doesn't NEED to send anything.
Maybe like, the connections themselves ARE the data.
Whoooaaa.
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the connections themselves ARE the data
Very good point.
Re:From TFA (Score:5, Interesting)
Some of the malware I've encountered lately (I've got one system unusable until I get around to reinstalling the OS) is very sophisticated indeed. I would admire the designers, if I didn't so badly want them dead.
Does anybody else miss script kiddies?
What it probably is? (Score:3, Interesting)
Probably one of a few things
1) They are looking for a particular vuln to make their bot bigger.
2) They are just testing a DOS.
3) They are actually conducting a DOS.
4) They are trying to make some sort of name for themselves.
5) Combination of the above.
My money is mostly on 1, and some sort of bug in the program causing it to spam the same boxes over and over.
SSL traffic (Score:3, Interesting)
Do they realise that SSL traffic causes a higher load on the server than a regular request? This would be an indication it is trying to bring the site down.
I don't see how sending packets to 'major websites' disguises the real communications in any way. Just filter those requests. The more 'major' the web site for the garbaage packets, the easier it is to distinguish them from the real packets.
Re:SSL traffic (Score:5, Informative)
Do they realise that SSL traffic causes a higher load on the server than a regular request? This would be an indication it is trying to bring the site down.
Requesting an SSL connection and then never making it takes a lot less load than actually retrieving a page. It doesn't really suggest a takedown attempt, for which there are superior strategies.
Re:SSL traffic (Score:5, Interesting)
Do they realise that SSL traffic causes a higher load on the server than a regular request? This would be an indication it is trying to bring the site down.
Yes, they do. They also don't care. Most botnet authors are self-taught, or only college educated, and are not experienced developers. They don't know how to obscure their creation's activity, because they lack a full understanding of network security. Which is understandable: That isn't in the SDK documentation and example code. Because they lack the skillset necessary to create a protocol resistant to traffic analysis, they go the other way: Flood all the connections and hope those analyzing the logs decide it's not worth the effort to find the needle in the haystack. They know it can be tracked -- they just don't feel its worth the effort to learn how to do it right, when doing it wrong gets them to payday faster and with only a minute amount of additional risk.
Re: (Score:3, Interesting)
[Citation needed] The guy that took over torpig has some very nice things to say about the quality of the logging info that suggests the complete opposite, botnet developers are damn good and produce a better product than most code-monkeys.
Re:SSL traffic (Score:4, Funny)
I would bet that on them not being CMMI certified and not writing their viruses in java...
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I dunno - what strategy could they possibly employ? They seem rather clever with their attacks IMHO.
Until we have DRM-enabled hardware in everybody's home, they have to work with conventional PCs. That means that an inspection of a PC will turn up the binary code to the virus, and its operation can be fully studied. Anybody attacking a bot can evesdrop on every aspect of its activity client-side, and can probably trace the network traffic pretty far (with government assistance all the way to the endpoint
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There's a lot of half-truth in your post. Botnet authors have wide ranges of experience and education. Sure, there are self-taught teenagers. But there are also professionals running botnets (on the payroll of the Ukrainian mafia, for example). Cybercrime is not a kid's game. Now that there's real money to be made, real money is being invested.
Any statement you make about all botnet authors is wrong.
Re:SSL traffic (Score:4, Interesting)
I can honestly say, with experience, that https only takes a trivial amount more CPU time than a http request.
The honest references you will find showing that https was so much heavier than http, was when the blazing fast webservers were 133Mhz.
You're in more danger of the DDoS filling up your pipe than bringing a server to it's knees. The bringing the server down could be accomplished just as easily as a http server. That is unless some genius decided that they needed an entire server farm for http, but only one or two machines for https, which would definately qualify it as "weak"
The folks running the servers should be able to deploy countermeasures of some sort. If a number over some acceptable threshold are illegitimate requests, automatically block them. It's easy enough on a *nix box. I'm not talking about anything in the webserver itself either. The webserver should be able to initiate something as simple as an iptables/ipfilter rule. It's amazing how useful those can be, and if the threshold is calculated appropriately, it won't even bother legitimate traffic.
You are right though, I don't see how these would disguise anything. If you have a list of places that are targets, that makes it more noticeable, not less, even if it is the CnC machine, or a drone.
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Is that so? I recently had to make a hardware budget for an SSL site, so I ran a few benchmarks on Apache and Nginx running on my MacBook Pro. Both of them handled only *50* requests/sec when serving static assets through SSL, as opposed to 3000+ when not serving through SSL. After some investigation it turns out that the SSL handshake is particularly expensive; once the handshake is done, the server can serve several thousand static assets per second. However not all browsers/routers/proxies support/allow
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Well, not to argue, but this is a test I just did on my desktop at work. I used the 'ab' test program, that comes with Apache (full name is Apache Bench).
800Mhz, 1.7Gb RAM available (256Mb shared to video)
Slackware Linux (x86_64) 13.0.0.0.0
Linux evil2 2.6.31.6 #8 SMP PREEMPT Thu Dec 3 14:44:04 EST 2009 x86_64 AMD Athlon(tm) Processor 2650e AuthenticAMD GNU/Linux
It is running Apache 1.3.41 with mod_ssl
The test was run
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Up to something? (Score:4, Interesting)
Is it an attempt to break in? (Score:1)
Re: (Score:2)
It's not. There's no exploit code sent, just random bytes and the replies are discarded.
How to stop bot nets (Score:2)
All it takes is to install an anti-virus and make a full scan you mom's and dad's PC next time.
Re:How to stop bot nets (Score:5, Insightful)
is that because the antivirus program makes the computer crawl to a halt so the bot program has no CPU resources left to run?
The FBI has already apprehended the culprits (Score:1, Funny)
The FBI has apprehended the individuals responsible for the Pushdo botnet, but because the said individuals are minors, we have decided to file no charges if the said individuals apologized to everyone who had been negatively affected by the Pushdo botnet. Unfortunately, due to a typo, the said individuals issued a botnet command that is causing the botnet computers to keep trying to POST the following apology to the SSL port:
POST / HTTP/1.0
Referer: http://ir902.detention.fbi.gov/ [fbi.gov]
User-Agent: PushDo/1.0.1
Acc
And they say obfuscation isn't a good defense (Score:2, Interesting)
Re:And they say obfuscation isn't a good defense (Score:4, Funny)
Obfuscation isn't good security. But, as any politician will tell you, it's excellent defense.
Entropy depletion (Score:5, Interesting)
SSL/TLS at it's core generates "session keys" for communication; a string of random characters. It's possible they're trying to deplete the SSL servers of true entropy for some undisclosed attack; PRNG, for example.
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You're right, sorry about that.
Re:Entropy depletion (Score:5, Interesting)
Don't think it's that complex. From June 2009:
http://isc.sans.org/diary.html?storyid=6601 [sans.org]
Yesterday an interesting HTTP DoS tool has been released. The tool performs a Denial of Service attack on Apache (and some other, see below) servers by exhausting available connections. While there are a lot of DoS tools available today, this one is particularly interesting because it holds the connection open while sending incomplete HTTP requests to the server.
In this case, the server will open the connection and wait for the complete header to be received. However, the client (the DoS tool) will not send it and will instead keep sending bogus header lines which will keep the connection allocated.
The initial part of the HTTP request is completely legitimate:
GET / HTTP/1.1\r\n .NET CLR 1.1.4322; .NET CLR 2.0.503l3; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729; MSOffice 12)\r\n
Host: host\r\n
User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Trident/4.0;
Content-Length: 42\r\n
After sending this the client waits for certain time – notice that it is missing one CRLF to finish the header which is otherwise completely legitimate. The bogus header line the tools sends is currently:
X-a: b\r\n
Which obviously doesn't mean anything to the server so it keeps waiting for the rest of the header to arrive. Of course, this all can be changed so if you plan to create IDS signatures keep that in mind.
According to the web site where the tool was posted, Apache 1.x and 2.x are affected as well as Squid, so the potential impact of this tool could be quite high considering that it doesn't need to send a lot of traffic to exhaust available connections on a server (meaning, even a user on a slower line could possibly attack a fast server). Good news for Microsoft users is that IIS 6.0 or 7.0 are not affected.
At the moment I'm not sure what can be done in Apache's configuration to prevent this attack – increasing MaxClients will just increase requirements for the attacker as well but will not protect the server completely. One of our readers, Tomasz Miklas said that he was able to prevent the attack by using a reverse proxy called Perlbal in front of an Apache server.
We'll keep an eye on this, of course, and will post future diaries or update this one depending on what's happening. It will be interesting to see how/if other web servers as well as load balancers are resistant to this attack.
Re: (Score:2)
Don't the packets send/received make up for the lost entropy?
I don't know very much about cryptography, but I'm thinking the same thing.
Intuitively, I'd expect the number of requests not controlled by the attacker to serve as an implicit entropy source for a PRNG, at least relative to that attacker. Intuitively, I'd expect the number of requests not controlled by the attacker to follow a Poisson distribution with lambda equal to the traffic frequency times the interval of time since the last request where the attacker was able to determine the state of the PRNG (no m
Re: (Score:2)
Intuitively, I'd expect the number of requests not controlled by the attacker to serve as an implicit entropy source for a PRNG, at least relative to that attacker. Intuitively, I'd expect the number of requests not controlled by the attacker to follow a Poisson distribution with lambda equal to the traffic frequency times the interval of time since the last request where the attacker was able to determine the state of the PRNG (no mean feat in itself).
EDIT FAIL!
I guess I liked that phrase so much that I just had to use it twice in a row.
Re: (Score:3, Interesting)
1) The code function does NOTHING with any data returned by the server.
2) This version of pushdo is using SSLv3 to phone home (HTTP over SSL) to its C2 (Command & Control).
3) When looking purely at netflow records or using tcpdump/wireshark, you will see 30+ SSL connections taking place at once. Only 1-2 of those connections is to the C2.
3.5) Many admins don't set up matching PTR records in DNS, so you won't easily be able to map back the IPs to the "common"/well-known hostnames.
4)
5) prof
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They're not. The connections are far too infrequent (15 connections, then sleep for 30 hours).
time for a bayesian protocol filter? (Score:2)
Roughly the same techniques used to identify spam can be used to identify abuse of a protocol. For example, there exist bayesian intrusion detection algorithms.
Maybe it is time for people to start using those techniques and figure out that something is wrong almost from the getgo.
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infected computers (Score:3, Informative)
"Once executed the malware first tests to see if it's currently running as the hardcoded value "rs32net.exe" in the system folder (C:\Windows\System32 [trendmicro.com] by default)"
Huh? (Score:4, Interesting)
I don't get it. Could someone please explain this to me?
If they're trying to disguise their traffic to the command-and-control center, how does this help? If you get a lot of malformed requests from a particular host, then if you're an investigator, it's like the infected computers are advertising themselves as zombies. And if they're sending these requests to major web sites, how does this disguise the requests they're making to the (presumably non-major website) control center? Couldn't you just say, "Well, this computer made 300 malformed SSL requests to Facebook, Twitter, et cetera, and one malformed request to , let's find that guy!"
I'm seriously confused.
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I think they're attempting to evade brain-dead automated protocol inspection, not trying to fool a human.
$employer is on the target list of pushdo drones (Score:3, Informative)
According to our graphs, our targeted frontend is taking the drone's trashy SSL requests like a champ (reverse-proxies are humming as expected, no inordinate load, etc).
You too can see if you are on the hitlist: http://www.shadowserver.org/wiki/pmwiki.php/Calendar/20100129 [shadowserver.org]
Over the last 24 hours add more to the list! (Score:2, Informative)