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October 7th, 2013

Beware of poisoned apples

loginEverybody knows the story of the beautiful Snow White. An evil queen with a bad temper gives a young girl a poisoned apple, because she apparently thinks that it would just make her day. Poor Snow White. All she wanted was a bite of this juicy apple. I guess this one particular bite didn’t make her very happy. Anyway, she apparently made some mistakes, that I can tell. For example, if she wanted an apple, she should have just picked one from a “genuine” tree. Or she could have had someone taste the apple first, like a brave knight that’s always there for her, protecting her every second.

Yes, it’s been a while since that famous apple incident happened. Nowadays, a girl wouldn’t just accept an apple from a stranger and take a bite right away. She would at least wash it first! If she’s smart enough, she’s going to have something that tells her more about the apple.

With the magic of fairy dust and special effects, let’s transform this story into the world of mobile security.

Poisoned APPles

The Snow White fairy tale came to life a few days ago, when we found a fake Apple iMessage app for Android. There are lot of apps for Apple iOS that are not released for other platforms. For example, when two people have an iPhone, they can send each other messages for free via Apple’s iMessage service. The Android alternative for that service would probably be Google’s Hangouts app. The problem occurs when you want to send a free text message from iOS to Android. Yes, there’s WhatsApp, Viber, and similar apps, but there’s no way to send an iMessage to Android, nor iMessage from Android. That problem seems to bother some people, so they are eagerly waiting for a solution. The evil queen is aware of the need, so she makes poisoned apples and hands them out for free, telling others that they are sweet, juicy, and absolutely free from poison. Yes, I’m talking about fake apps that are trying to look like official Apple apps for Android. Read more…

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September 25th, 2013

Win32/64:Napolar: New Trojan shines on the cyber crime-scene

In recent weeks, malware samples resolved as Win32/64:Napolar from AVAST’s name pools generated a lot of hits within our file and network shields. Independently, we observed an advertising campaign of a new Trojan dubbed Solarbot that started around May 2013. This campaign did not run through shady hacking forums as we are used to, but instead it ran through a website indexed in the main search engines. The website is called http://solarbot.net and presents its offer with a professional looking design:

_napolar_intro

For the Win32/64:Napolar Trojan, the pipe used to inter-process communication is named \\.\pipe\napSolar. Together with the presence of character strings like “CHROME.DLL,” “OPERA.DLL,” “trusteer,” “data_inject,” and features we’ll mention later, we have almost no doubts that the Trojan and Solarbot coincide. Let us look at some analysis.

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August 27th, 2013

Linux Trojan “Hand of Thief” ungloved

A new threat for the Linux platform was first mentioned on August 7th by RSA researchers, where it was dubbed Hand of Thief.  The two main capabilities of this Trojan are form-grabbing of Linux-specific browsers and entering a victim’s computer by a back-door. Moreover, it is empowered with features like anti-virtualization and anti-monitoring. With the level of overall sophistication Hand of Thief displays, it can be compared to infamous non-Windows threats such as the FlashBack Trojan for MacOsX platform discovered last year or Trojan Obad for Android from recent times.

A detailed analysis uncovers the following structure of the initial file with all parts after the dropper being encrypted (hexadecimal number displays starting offset of a block):

handofthief_scheme

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August 20th, 2013

No problem bro – ransom decryption service

If thieves gain control of sensitive personally identifiable information (PII) on your computer, your identity can be stolen.  Information such as your social security number, driver’s license number, date of birth, or full name are examples of files that should be encrypted.  Confidential business data like individual customer information or intellectual property should also be encrypted for your safety.

In this blog post we will look at a service offering file decryption. This service helps you to decrypt files which were previously encrypted. But this is no helpful ‘Tips and Tricks’ blog for people who forgot the password to their documents and ask for help recovering it. Although breaking weak passwords is quite possible, noproblembro.com specializes in a different type of service.

01-noproblembro

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Categories: analyses, Virus Lab Tags: , ,
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August 12th, 2013

Your documents are corrupted: From image to an information stealing trojan

InfoStealer is a Trojan that collects sensitive information about the user from an affected computer system and forwards it to a predetermined location. This information, whether it be financial information, log in credentials, passwords, or a combination of all of them, can then be sold on the black market. AVAST detects this infostealer as MSIL:Agent-AKP.

In this blogpost, we will look at a malicious .NET file served to a victim’s computer via an exploit kit. After opening the file in decompiler, we noticed resources containing only noisy images similar to the figure below.

msil-img-00

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August 1st, 2013

Malicious Bitcoin Miners target Czech Republic

Single BitcoinToday we are going to talk to those of you who use Bitcoin digital currency to pay for a variety of goods and services – along with a warning about yet another source of Bitcoin miners – the sharing services. You may think that if you avoid cracks and keygens while browsing the web you will be safe. Well, we would recommend that you reconsider that position. Recently we found that on the uloz.to file sharing service someone uploaded a lot of fake files containing Bitcoin miners!

Bitcoin Mining service

First a little background for the uninitiated: Bitcoins can be obtained by trading real currency, goods, or services with people who have them or alternatively, through mining. The mining process involves running software that performs complex math problems for which you’re rewarded a share of the income. There are a finite amount of Bitcoins to be had, and mining for them can be compared to extracting gold or diamonds from the earth. The more you get, the fewer there are to be had, so it becomes increasingly harder and more expensive. Here’s a descriptive article about mining.

Bitcoin mining services such as bitminter.com use shared computer resources of their users to mine new Bitcoins. In order to participate, the mining users have to create an account and then register their computers (workers) with the service. Then they simply run the Bitcoin miner program provided with their credentials on as many computers as they have. In the end, if they had enough computation power and time they might end up with a few Bitcoins.

It can be expected that some people will not be satisfied just using their own machines so they will try to use the computing power of unsuspecting victims. And that’s exactly what the authors of this malware are doing: They use hardware that does not belong them to generate more money.

It’s not a Bitcoin problem; it’s a people problem

We must stress that there’s nothing wrong with Bitcoin or its mining services. The problem is that some greedy people are misusing them.

Some of them can be seen on the following image.  The word “cestina” means that the file should contain Czech localization of the referenced program. All of them contain a hidden feature, and sometimes the name is a complete fabrication. For example, The-Night-of-the-Rabbit-cestina.exe contains a crack for Call of Duty 4. Notice too, that all these files have an elevated popularity; no doubt a result of tampering. Some downloaders already suspect something fishy about these files.

Uloz.to malicious filesWarning comment on the sharing server.

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July 22nd, 2013

Multisystem Trojan Janicab attacks Windows and MacOSX via scripts

On Friday, July 12th a warning from an AVAST fan about a new polymorphic multisystem threat came to an inbox of AVAST. Moreover, an archive of malicious files discussed here were attached. Some of them have been uploaded to Virustotal and therefore they have been shared with computer security professionals on the same day. A weekend had passed by and articles full of excitement about a new Trojan for MacOs started to appear on the web. We decided to make a thorough analysis and not to quickly jump on the bandwagon. The key observation is that the final payload comes in the form of scripts needed to be interpreted by Windows Script Console resp; Python in the case of MacOs. Moreover a script generator that creates new malicious Windows file shortcuts was also included.

Windows version

A chain of events that installs a malicious Visual Basic script on Windows platform looks like this:

win32_janicab_chain

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Categories: analyses, Mac, Virus Lab Tags:
July 3rd, 2013

Fake Flash Player installer spreads via Twitter and Facebook

Recently we identified a threat which uses Twitter and Facebook to spread. The origin of the infection begins by clicking malicious tweets or Facebook posts.

fakeflash_sc01
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June 25th, 2013

Story of the Cutwail/Pushdo hidden C&C server

This is a loose sequel to the Cutwail botnet analysis blogpost published on the malwaremustdie.blogspot.com. In this blogpost I will primarily focus on the downloaded PE executable itself (SHA256: 5F8FCC9C56BF959041B28E97BFB5DB9659B20A6E6076CFBA8CB2D591184C9164) and the network traffic that it generates. I will also reveal a hidden C&C server.

But first let’s quickly go through the things it does at the beginning:
- It registers an exception handler that will only start the process again using CreateProcess().
- It performs a check whether it has admin privileges.
- It checks or creates a mutex named “xoxkycomvoly” (hardcoded identifier used on multiple occasions).
- It checks or creates couple of registry entries under HKCU\Software\Microsoft\Windows\CurrentVersion.
- It checks if the process image filename is “xoxkycomvoly.exe” (it restarts for the first time).
- It nests into the system by creating autorun entry in registry under HKCU\Software\Microsoft\Windows\CurrentVersion\Run.
- It copies itself to the user’s profile directory named as “xoxkycomvoly.exe”.
Then on the first time an exception occurs and the sample is restarted from the user’s profile location named as “xoxkycomvoly.exe”.

Initial startup activities

Initial startup activities

After these initial steps, the sample starts communicating heavily over the network.
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June 18th, 2013

Your Facebook connection is now secured! Thank you for your support!

The title of this blog post may make you think that we will discuss the security of your Facebook account. Not this time. However, I will analyze an attack which starts with a suspicious email sent to the victim’s email account.

The incoming email has the following subject, ‘Hey <name> your Facebook account has been closed!‘ or ‘Hi <name> your Facebook account is blocked!‘. The email has a ZIP file attachment with name <name>.zip, which contains a downloader file named <name>.exe. <name> stands for a random user name. After a user downloads and executes the executable file, he is presented with the message saying that “Your Facebook connection is now secured! Thank you for your support!” It tries to convince you that there was a problem with your Facebook account, which was later successfully solved by executing the application from the email attachment.

Let’s look inside the executable file!

fbsec01

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