INTECO-CERT

This week, our virus lab handled a case where a customer received a phishing email with an Android Backdoor archive masquerading as a Kaspersky mobile security app (we are aware that those who created this app are also disguising it as apps from other major AV brands).

It prompts recipients to install the fake Kaspersky Android app to protect their mobile security. From the context we can presume the intended targets are users in Poland.

Most email phishing attacks tend to target PC users, but this time the attackers have turned their attention to mobile platforms. We think it's a new trend in spreading virus. Mobile security is related to user privacy. In most cases, a mobile device is more important than PC for users. It contains user contacts, text messages, photos and call logs. And mobile security is generally considered to be a weak point. So, most people will believe these phishing emails and are likely to install the fake mobile security app.

In this case, the Android apk in the phishing email is a powerful and aggressive backdoor which is detected as Backdoor.AndroidOS.Zerat.a. The backdoor is full of malicious functions, but the GUI is a little simple and crude.

Maybe it only wants you to install it and click the button. By executing, it links to hxxp://winrar.nstrefa.pl/path/DeviceManager.php to register the victim device info.

Then it visits hxxp://winrar.nstrefa.pl/path/Linker.php to get commands.

According to the commands, it will perform lots of malicious activities.

Some of the commands are shown below.
Getting location:

Recording:

Intercepting text messages:

Browsing history:

Recording call:

Store and upload:

This is a new type of mobile security threat that works just like a phishing site or phishing SMS. With the phishing email, the backdoor will spread more easily. There is reason to believe that more increasingly complex mobile attacks with follow. Composite attacks on mobile platforms are simply a matter of time.

In this day and age it is very important to protect our privacy and device security. It's recommended to follow these tips:

• Download a mobile security app from the official Kaspersky website.
• Don't trust strange emails.
• Don't just open and execute files in email attachments.

On August 2, the Chinese Valentine's Day, an Android SMS worm struck China. It is called XXshenqi.apk. In the space of six hours, it infected about 500,000 devices. It has received widespread coverage in the local media. It's not just an SMS worm, containing two malicious modules: XXshenqi.apk and its asset Trogoogle.apk.

The function of XXshenqi.apk is to send SMS to spread itself and to drop another backdoor on the victim device. It is detected as Trojan.AndroidOS.Xshqi.a by Kaspersky Lab.

After installation, it sends an SMS to all the names on the victim's contact lists to get them to install the Trojan as well.

Then it probes whether or not com.android.Trogoogle.apk is present on the mobile device. If not, it displays a dialog window to prompt the user to install Trogoogle.apk.

Trogoogle.apk is a resource file in the assets folder of XXshenqi.apk.

After that, it asks the user to register the app. The Trojan will steal the user's personal ID and name and send them to those controlling the malware.

Trogoogle.apk contains more malicious functions. It is a backdoor and detected as Backdoor.AndroidOS.Trogle.a by Kaspersky Lab. It hides its icon after installation so the user is unaware of its presence. It will then respond to commands to perform malicious activity. The commands include:

"readmessage"
"sendmessage"
"test"
"makemessage"
"sendlink"

It also monitors the victim's text messages and sends them to the malware owner by email or SMS.

The fact that this Trojan combintion appeared on the Chinese Valentine's Day is premeditated, taking advantage of user credulity on this special day. And it uses social engineering techniques to spread as much as possible and infect more devices. This Trojan is a good example of why it's always worth thinking twice about trusting a link received on your mobile phone. No matter who sends it, it could still be a malicious program.

A couple weeks ago, my colleague Mikhail K posted on the "versatile linux DDoS trojan", with analysis of several bots, including a bot implementing some extraordinary DNS amplification DDoS functionality. Operators of these bots are currently active, and we observe new variants of the trojan building bigger botnets.

Let's explore some additional offensive details of this crew's activity, and details of the overall situation, in the past week. In general, the DDoS trojans are being distributed to fire on victim profiles that seem to indicate purely cybercrime activity. The compromised hosts used to run the bots we observed have been running Amazon EC2 instances, but of course, this platform is not the only one being attacked and mis-used. It's also interesting that operators of this botnet apparently have no problem working with CN sites, as demonstrated by their use of the site hosting their tools since late 2013. Seven of their eight tools hosted here were uploaded in the past couple of weeks, coinciding with their updated attack activity. Their repository includes recent (cve-2014-0196) and older (cve-2012-0056) Linux escalation of privilege exploit source code, likely compiled on the compromised hosts only when higher privileges are necessary, along with compiled offensive sql tools (Backdoor.Linux.Ganiw.a), multiple webshell (Backdoor.Perl.RShell.c and Backdoor.Java.JSP.k) and two new variants of the "versatile bots" (Backdoor.Linux.Mayday.g), the udp-only "xudp" code being the newer of the two:

But first, how are they getting in to EC2 instances and running their linux DDoS bots from the cloud? They are actively exploiting a known, recent elasticsearch vulnerability in all versions 1.1.x (cve-2014-3120), which happens to still be in active commercial deployment for some organizations. If you are still running 1.1.x, upgrade to the latest 1.2 or 1.3 release, which was released a couple of days ago. Dynamic scripting is disabled by default, and other features added to help ease the migration. From a couple of incidents on Amazon EC2 customers whose instances were compromised by these attackers, we were able to capture very early stages of the attacks. The attackers re-purpose known cve-2014-3120 proof-of-concept exploit code to deliver a perl webshell that Kaspersky products detect as Backdoor.Perl.RShell.c. Linux admins can scan for these malicious components with our server product.

Gaining this foothold presents the attacker with bash shell access on the server. The script "pack.pl" is fetched with wget and saved from the web host above to /tmp/zerl and run from there, providing the bash shell access to the attacker. Events in your index logs may suggest your server has fallen to this attack:

Hosted on the same remote server and fetched via the perl webshell are the DDoS bots maintaining new encrypted c2 strings, detected as Backdoor.Linux.Mayday.g. One of the variants includes the DNS amplification functionality described in Mikhail's previous post. But the one in use on compromised EC2 instances oddly enough were flooding sites with UDP traffic only. The flow is strong enough that the DDoS'd victims were forced to move from their normal hosting operations ip addresses to those of an anti-DDoS solution. The flow is also strong enough that Amazon is now notifying their customers, probably because of potential for unexpected accumulation of excessive resource charges for their customers. The situation is probably similar at other cloud providers. The list of the DDoS victims include a large regional US bank and a large electronics maker and service provider in Japan, indicating the perpetrators are likely your standard financially driven cybercrime ilk.