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Aug 17

Tech Firms Team Up to Take Down ‘WireX’ Android DDoS Botnet

A half dozen technology and security companies — some of them competitors — issued the exact same press release today. This unusual level of cross-industry collaboration caps a successful effort to dismantle ‘WireX,’ an extraordinary new crime machine comprising tens of thousands of hacked Android mobile devices that was used this month to launch a series of massive cyber attacks.

Experts involved in the takedown warn that WireX marks the emergence of a new class of attack tools that are more challenging to defend against and thus require broader industry cooperation to defeat.

This graphic shows the rapid growth of the WireX botnet in the first three weeks of August 2017.

This graphic shows the rapid growth of the WireX botnet in the first three weeks of August 2017.

News of WireX’s emergence first surfaced August 2, 2017, when a modest collection of hacked Android devices was first spotted conducting some fairly small online attacks. Less than two weeks later, however, the number of infected Android devices enslaved by WireX had ballooned to the tens of thousands.

More worrisome was that those in control of the botnet were now wielding it to take down several large websites in the hospitality industry — pelting the targeted sites with so much junk traffic that the sites were no longer able to accommodate legitimate visitors.

Experts tracking the attacks soon zeroed in on the malware that powers WireX: Approximately 300 different mobile apps scattered across Google‘s Play store that were mimicking seemingly innocuous programs, including video players, ringtones or simple tools such as file managers.

“We identified approximately 300 apps associated with the issue, blocked them from the Play Store, and we’re in the process of removing them from all affected devices,” Google said in a written statement. “The researchers’ findings, combined with our own analysis, have enabled us to better protect Android users, everywhere.”

Perhaps to avoid raising suspicion, the tainted Play store applications all performed their basic stated functions. But those apps also bundled a small program that would launch quietly in the background and cause the infected mobile device to surreptitiously connect to an Internet server used by the malware’s creators to control the entire network of hacked devices. From there, the infected mobile device would await commands from the control server regarding which Websites to attack and how.

A sampling of the apps from Google's Play store that were tainted with the WireX malware.

A sampling of the apps from Google’s Play store that were tainted with the WireX malware.

Experts involved in the takedown say it’s not clear exactly how many Android devices may have been infected with WireX, in part because only a fraction of the overall infected systems were able to attack a target at any given time. Devices that were powered off would not attack, but those that were turned on with the device’s screen locked could still carry on attacks in the background, they found.

“I know in the cases where we pulled data out of our platform for the people being targeted we saw 130,000 to 160,000 (unique Internet addresses) involved in the attack,” said Chad Seaman, a senior engineer at Akamai, a company that specializes in helping firms weather large DDoS attacks (Akamai protected KrebsOnSecurity from hundreds of attacks prior to the large Mirai assault last year).

The identical press release that Akamai and other firms involved in the WireX takedown agreed to publish says the botnet infected a minimum of 70,000 Android systems, but Seaman says that figure is conservative.

“Seventy thousand was a safe bet because this botnet makes it so that if you’re driving down the highway and your phone is busy attacking some website, there’s a chance your device could show up in the attack logs with three or four or even five different Internet addresses,” Seaman said in an interview with KrebsOnSecurity. “We saw attacks coming from infected devices in over 100 countries. It was coming from everywhere.”

BUILDING ON MIRAI

Security experts from Akamai and other companies that participated in the WireX takedown say the basis for their collaboration was forged in the monstrous and unprecedented distributed denial-of-service (DDoS) attacks launched last year by Mirai, a malware strain that seeks out poorly-secured “Internet of things” (IoT) devices such as security cameras, digital video recorders and Internet routers.

The first and largest of the Mirai botnets was used in a giant attack last September that knocked this Web site offline for several days. Just a few days after that — when the source code that powers Mirai was published online for all the world to see and use — dozens of copycat Mirai botnets emerged. Several of those botnets were used to conduct massive DDoS attacks against a variety of targets, leading to widespread Internet outages for many top Internet destinations.

Allison Nixon, director of security research at New York City-based security firm Flashpoint, said the Mirai attacks were a wake-up call for the security industry and a rallying cry for more collaboration.

“When those really large Mirai DDoS botnets started showing up and taking down massive pieces of Internet infrastructure, that caused massive interruptions in service for people that normally don’t deal with DDoS attacks,” Nixon said. “It sparked a lot of collaboration. Different players in the industry started to take notice, and a bunch of us realized that we needed to deal with this thing because if we didn’t it would just keep getting bigger and rampaging around.”

Mirai was notable not only for the unprecedented size of the attacks it could launch but also for its ability to spread rapidly to new machines. But for all its sheer firepower, Mirai is not a particularly sophisticated attack platform. Well, not in comparison to WireX, that is.

CLICK-FRAUD ORIGINS

According to the group’s research, the WireX botnet likely began its existence as a distributed method for conducting “click fraud,” a pernicious form of online advertising fraud that will cost publishers and businesses an estimated $16 billion this year, according to recent estimates. Multiple antivirus tools currently detect the WireX malware as a known click fraud malware variant.

The researchers believe that at some point the click-fraud botnet was repurposed to conduct DDoS attacks. While DDoS botnets powered by Android devices are extremely unusual (if not unprecedented at this scale), it is the botnet’s ability to generate what appears to be regular Internet traffic from mobile browsers that strikes fear in the heart of experts who specialize in defending companies from large-scale DDoS attacks.

DDoS defenders often rely on developing custom “filters” or “signatures” that can help them separate DDoS attack traffic from legitimate Web browser traffic destined for a targeted site. But experts say WireX has the capability to make that process much harder.

That’s because WireX includes its own so-called “headless” Web browser that can do everything a real, user-driven browser can do, except without actually displaying the browser to the user of the infected system.

Also, Wirex can encrypt the attack traffic using SSL — the same technology that typically protects the security of a browser session when an Android user visits a Web site which requires the submission of sensitive data. This adds a layer of obfuscation to the attack traffic, because the defender needs to decrypt incoming data packets before being able to tell whether the traffic inside matches a malicious attack traffic signature.

Translation: It can be far more difficult and time-consuming than usual for defenders to tell WireX traffic apart from clicks generated by legitimate Internet users trying to browse to a targeted site.

“These are pretty miserable and painful attacks to mitigate, and it was these kinds of advanced functionalities that made this threat stick out like a sore thumb,” Akamai’s Seaman said.

NOWHERE TO HIDE

Traditionally, many companies that found themselves on the receiving end of a large DDoS attack sought to conceal this fact from the public — perhaps out of fear that customers or users might conclude the attack succeeded because of some security failure on the part of the victim.

But the stigma associated with being hit with a large DDoS is starting to fade, Flashpoint’s Nixon said, if for no other reason than it is becoming far more difficult for victims to conceal such attacks from public knowledge.

“Many companies, including Flashpoint, have built out different capabilities in order to see when a third party is being DDoS’d,” Nixon said. “Even though I work at a company that doesn’t do DDoS mitigation, we can still get visibility when a third-party is getting attacked. Also, network operators and ISPs have a strong interest in not having their networks abused for DDoS, and many of them have built capabilities to know when their networks are passing DDoS traffic.”

Just as multiple nation states now employ a variety of techniques and technologies to keep tabs on nation states that might conduct underground tests of highly destructive nuclear weapons, a great deal more organizations are now actively looking for signs of large-scale DDoS attacks, Seaman added.

“The people operating those satellites and seismograph sensors to detect nuclear [detonations] can tell you how big it was and maybe what kind of bomb it was, but they probably won’t be able to tell you right away who launched it,” he said. “It’s only when we take many of these reports together in the aggregate that we can get a much better sense of what’s really going on. It’s a good example of none of us being as smart as all of us.”

According to the WireX industry consortium, the smartest step that organizations can take when under a DDoS attack is to talk to their security vendor(s) and make it clear that they are open to sharing detailed metrics related to the attack.

“With this information, those of us who are empowered to dismantle these schemes can learn much more about them than would otherwise be possible,” the report notes. “There is no shame in asking for help. Not only is there no shame, but in most cases it is impossible to hide the fact that you are under a DDoS attack. A number of research efforts have the ability to detect the existence of DDoS attacks happening globally against third parties no matter how much those parties want to keep the issue quiet. There are few benefits to being secretive and numerous benefits to being forthcoming.”

Identical copies of the WireX report and Appendix are available at the following links:

Flashpoint

Akamai

Cloudflare

RiskIQ

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25 comments

  1. Google controls the gateways to world communication and commerce and by its’ failure or success we rise or fall. (I refer to the compromised apps on Google Play Store discussed here). Is it time for Google be regulated by government like other utilities?

    • Regulated by the government? You mean the clueless gang that still doesn’t have its own servers locked down, right?

        • Google + Government Regulators + Stupid People = Disaster. Only using Google for collecting info on products keeping business email apart. IOS I-Phone becoming less secure like Android. Whats needed is a pure Linux locked down device, but the carriers probably don’t want a locked down device? Android just makes it to easy and easy is what Google wants for their own purposes.

    • NO. More like they need to alert people that downloaded malware from them. Google removes apps for having malware but never notifies the users that downloaded it though them, even though you have to have a valid Email to do so.
      I’m hoping there is a class action suite against google for negligence for this.

  2. The thing I never saw released was the list of applications that had used the SDK which did all of this.

    • I tried to find a list of the affected apps but no luck. I did find out that most of them are used overseas so not as big a threat here as elsewhere in the world. I stay off Google Play unless I really need a specific app. I disable it when I don’t need it.

      • If it was malicious – disabling won’t help once it’s ran. The most popular malware are downloaders that install other apps. passing their permissions and you never know it’s on there.
        Disable or remove the original app, the malware stays.

  3. So many companies have been hit by DDoS now it’s become “normal” so there’s no reason to hide it. PR could even spin it and say something like “someone thinks we’re important enough to try to shut us down”.

  4. Just goes to show that Google doesn’t do as good of a job as Apple does at analyzing what’s put on their store. Not that Apple is perfect, but it’s interesting to me that Android has more vulnerabilities than iOS.

    • Androids market share makes it a more attractive target, but there has been similar attacks on iOS too, only smaller in scale.
      Are we to fix this problem, we need to end the finger-pointing and focus on cooperation, much like was done in this case.

    • Google made quite a bit of hay last month about their Play Protect App, which was a big improvement on Bouncer, but this discovery that 300+ apps in the Google Play Store were infected with malware will likely drive that team to better understand how this slice of malware was missed.

  5. I always use the Android setting “Restrict background data.” This prevents apps that are running in the background from using data.

    Seems like that would prevent WireX from working on my phone.

    • Where can that setting be found?
      Probably in Settings, but where within it?

      • Settings > Data Usage > menu > checkbox “Restrict background data”

        • In Stock (Nexus) Android N, you can turn on Data Saver and that is supposed to turn off background data usage for anything you don’t prositively grant exception.

          • Actually, ignore that. The mode I listed is only to save usage on the cellular network and has no effect on wifi usage.

            The “restrict background data” option vb mentioned is not available.

      • It appears to depend on the Android version and dialect. My Samsungized Android 5.0 (on a SM-N9005) does not appear to have that switch. The closest thing I’ve found is to go to WiFi, open the menu and go to Advanced. There, I can set WiFi to turn off during sleep. Would I then keep Mobile Data off, except when actually using it, I’d likely be less malware-friendly. I guess there may be apps for this too, which I guess malware makers would love to subvert…

        • Nevermind… I found the “restrict background data” now, exactly where advertised… Strange it didn’t show up when I (lazily) used the settings search feature. Makes search kind of pointless, it would seem.

  6. Most phones tend to change IPs very often unless using WI-FI, so this would easily account for the large number of IP addresses. But give the large number of phones, this issue should cause concern to everyone.

    Frankly, I don’t think the industry has gotten the “wake up call” yet and I am not sure they will until we have a 9/11 scale incident. But my fear is that it may make 9/11 look like a “brick through the window”.

    And I also worry that DDOS attacks may be just providing “cover” for other activity. Who is going to worry about a single breech to steal data when a DDOS takes down entire subnets?

    We need to get serious about protecting our cyber infrastructure before we wake up to find we have overslept and are up some foul-smelling creek without a packet paddle.

    • @ChrisNielsen

      Many companies have internal processes to investigate for security breaches during DDOS events for this reason. Probably plenty that don’t but they also don’t care about their IT until theres a dumpster fire.

  7. This is very interesting but you need to be sure you don’t mix this up with the digital process that ham radio operators use to daily to talk to one and another. They are two different programs with the same name. So please check it out and let the world know that this isn’t the Ham radio digital mode.

    Thanks!

  8. Would be interesting to know whether all of the apps were from the same developer, or a small group of developers, in the Google play store. It would seem that criminal charges should be filed against the developers.

  9. How does google even know if this is on anything in playstore. It also being mitm into phones by bluetooth. All the code encrypted so it don’t trigger any antivirus software. That or some other remote admin tools. There nothing a person able to do to fight the ones doing this crap to them. Worse thing is Bluetooth has no security in it at all.