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Archive for the ‘analyses’ Category
April 1st, 2014

Email with subject “FW:Bank docs” leads to information theft

In this blogpost we will look deep into a spam campaign, where unlike other possible scenarios, the victim is infected by opening and running an email attachment. In the beginning of this year, we blogged about a spam campaign with a different spam message – a fake email from the popular WhatsApp messenger. This time we will look at spam email which tries to convince the victim that it originates from his bank. The malicious email contains contents similar to the following one:


Subject: FW: Bank docs

We have received this documents from your bank, please review attached documents.
<name, address>

 

promo Read more…

March 27th, 2014

Pretty women. Which one will infect you?

which_one_will_infect_you

Malware which opens pictures of attractive women to entice its victims has been around for some time. Last month there were more than usual, so I decided to research malware that pretends to be a regular picture, and the results are pretty interesting.

We looked for executable samples with two distinct characteristics: 1. .jpg in their name, and 2. no older than the last three months. About 6,000 unique files which matched this criteria were found. From these samples, we noticed that pretending to be an image is not a family specific criteria but we identified that Win32:Zbot is represented more than other malware e.g. MSIL:Bladabindi-EV, Win32:Banker-JXB,BV:Bicololo-CY, etc.

The important message is that most of these samples are distributed by scams which are sent by email or posted on social media sites. An example of an email scam is pictures below. If you are interested in what the social media scam looks like and how to protect yourself, you should read one of our previous blog posts.

scam_mails

Read more…

March 18th, 2014

Fake Korean bank applications for Android – Pt 3

Recently, we discovered an account on GitHub, a service for software development projects, that has interesting contents. The account contains several projects; one of the latest ones is called Banks, and it has interesting source codes.  The account contains information like user name, photo, and email address, but we cannot tell who the guy in the picture is. He might not be related to the contents at all, it could be a fake picture, fake name, or simply his account may have been hacked, his identity stolen, and the Banks repository created by someone else without his consent. In this blog post, we will explore the source codes in detail.
korea-03

When we downloaded the repository, we found several directories – GoogleService and fake applications imitating mobile applications of five major Korean banks – NH Bank, Kookmin Bank, Hana Bank, ShinHan Bank and Woori Bank.

korea-02

 

We previously published two blog posts with analyses of the above mentioned fake applications.

When we look at GitHub statistics, and Punchcard tab, it tells us what time the creators were most active. From the chart below you can see, that Saturday mornings and evenings and Sunday evenings were the most active times of comments of new versions. It seems that authors of this application do the development as a weekend job. At the time of writing this blogpost, the last update of fake bank applications was in the beginning of January 2014.

korea-20

This is not the first attack against users of Korean banks. About a year ago, we published this analysis.

Conclusion

Github, the web-based hosting service for software development projects, offers a lot of interesting contents, which depending on its settings can be later found and accessed by virtually anyone, including Google robots.  We managed to find the above mentioned repository by simply Googling the strings which occurred in a malicious Android application.

Acknowledgement:

The author would like to thank to Peter Kalnai and David Fiser for help and consultations related to this analysis.

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March 7th, 2014

Google Play: Whats the newest threat on the official Android market?

Official app stores are the primary sources to finding and downloading apps. Experts advise users to stay within the official app stores as they are approved ecosystems, which are widely recognized as safe. But are these sources really trustworthy? Some experts, however, claim that “Android malware is non-existent and security companies just try to scare us. Keep calm and don‘t worry.“ So which is it?

We’ve already blogged about plenty of threats that sneak onto your device from trusted sources, but here we have a really fresh one, one that  is still undetected by other security vendors. An Application called Cámara Visión Nocturna (package name: com.loriapps.nightcamera.apk), which is still available in the Google Play Store as I am writing this post, is something you definitely don’t want to have on your Android device.

Blg1

Starting with the application’s permissions you might notice there are some unusual requests for an app that should be able to work only using your camera.

    <uses-permission android:name=”android.permission.CAMERA” />

Read more…

March 3rd, 2014

Fake Korean bank applications for Android – part 2

In February, we looked at the first part of the fake Korean bank application analysis along with Android:Tramp (TRAck My Phone malicious Android application), which uses it. In this blogpost, we will look at another two Android malware families which supposedly utilize the same bunch of fake Korean bank applications. At the end of this article, we will discuss the origin of malware creators.

Analysis of Android:AgentSpy

It is interesting to search for references of bank applications package names – KR_HNBank, KR_KBBank, KR_NHBank, KR_SHBank, KR_WRBank. One reference goes to a malicious application called Android:AgentSpy. The infection vector of this application was described by Symantec, contagio mobile and Alyac. We will not delve into details, we will just mention that the malicious application is pushed to a connected mobile phone via ADB.EXE (Android Debug Bridge). The uploaded malicious file is called AV_cdk.apk.

Android:AgentSpy contains activity MainActivity and several receivers and service CoreService.

BootBroadcastReceiver

Monitors android.intent.action.BOOT_COMPLETED and android.intent.action.USER_PRESENT and if received, starts CoreService. It also monitors attempts to add or remove packages – android.intent.action.PACKAGE_ADDED and android.intent.action.PACKAGE_REMOVED.

CoreService

1) Calls regularly home and reports available connection types (wifi, net, wap), IMSI, installed bank apps

2) Regularly polls C&C and responds to the following commands

sendsms – sends SMS to a given mobile number

issms – whether to steal received SMS or not

iscall – whether to block outgoing call

contact – steals contact information and upload them to C&C

apps – list of installed bank apps

changeapp – replaces original bank applications with fake bank applications

move – changes C&C server

PhoneListener receiver

Moniors new outgoing calls. If android.intent.action.NEW_OUTGOING_CALL is received, information about the outgoing call is sent to C&C.

Config class

Contains C&C URL, name of bank packages (String array bank), name of fake bank packages (String array apkNames). It also contains reference to conf.ini configuration file.

koreanbanks_agentspy_config

Analysis of Android:Telman

One more Android malware family, which uses fake bank applications is called Android:Telman. Similarly to Android:Tramp and Android:AgentSpy, it checks for installed packages of the above mentioned banks. Read more…

February 17th, 2014

Fake Korean bank applications for Android – PT 1

About a year ago, we published this analysis about a pharming attack against Korean bank customers. The banks targeted by cybercriminals included NH Bank, Kookmin Bank, Hana Bank, ShinHan Bank, and Woori Bank. With the rise of Android-powered devices, these attacks now occur not only on the Windows platform, but also on the Android platform. In this blogpost we will look at a fake bank application and analyze several malware families which supposedly utilize them.

Original bank application

We will show just one bank application for brevity. For other banks the scenario is similar. The real Hana Bank application can be downloaded from Google Play. It has the following layout and background.
korea-08

Read more…

January 27th, 2014

Malformed FileZilla FTP client with login stealer

Beware of malformed FileZilla FTP client versions 3.7.3 and 3.5.3. We have noticed an increased presence of these malware versions of famous open source FTP clients.

The first suspicious signs are bogus download URLs. As you can see, the installer is mostly hosted on hacked websites with fake content (for example texts and user comments are represented by images.)

web_01 web_02 web_03

 

Malware installer GUI is almost identical to the official version. The only slight difference is version of NullSoft installer where malware uses 2.46.3-Unicode and the official installer uses v2.45-Unicode. All other elements like texts, buttons, icons and images are the same.

The installed malware FTP client looks like the official version and it is fully functional! You can’t find any suspicious behavior, entries in the system registry, communication or changes in application GUI.

The only differences that can be seen at first glance are smaller filesize of filezilla.exe (~6,8 MB), 2 dll libraries ibgcc_s_dw2-1.dll and libstdc++-6.dll (not included in the official version) and information in “About FileZilla” window indicates the use of older SQLite/GnuTLS versions. Any attempt to update the application fails, which is most likely a protection to prevent overwriting of malware binaries.

about_windows

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January 22nd, 2014

Win32/64:Blackbeard & Pigeon: Stealthiness techniques in 64-bit Windows, Part 2

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Last week we promised to explain in detail how the “Blackbeard” Trojan infiltrates and hide itself in a victim’s system, especially on its 64-bit variant. Everything described in this blogpost happens just before Pigeon (clickbot payload) gets downloaded and executed. The most interesting aspects are the way it bypasses the Windows’ User Access Control (UAC) security feature and switches the run of 32-bit code of the Downloader to 64-bit code of the Payload. And finally, how the persistence is achieved.

From 32-bit Loader to 64-bit Payload

As almost all other malware, this downloader is encapsulated with a cryptor. After removing the first layer cryptor, we can see that the downloader is written in a robust way. The same code can be run under either a 32-bit or 64-bit environment, which the code itself decides on the fly based on the entrypoint of the unpacked layer. Authors can therefore encapsulate their downloader in either a 32-bit or 64-bit cryptor and it will get executed well in both environments.

Read more…

January 15th, 2014

Win32/64:Blackbeard & Pigeon: Stealthiness techniques in 64-bit Windows, Part 1

clickfraud2At the turn of the year we started to observe a Trojan, not much discussed previously (with a brand new final payload). It has many interesting aspects: It possesses a complex structure containing both 32-bit and 64-bit code; it achieves its persistence with highly invasive methods; and it is robust enough to contain various payloads/functionalites.

Evolution of Blackbeard

Confronting this threat for the first time, we wondered about its classification. Using AVAST’s Malware Similarity Search, we found an old sample (the TimeStamp said “02 / 20 / 12 @ 3:30:55am UTC”) in the malware database that shared the threat’s structure of PE header. Moreover, it also contained debug info with a string “Blackbeard,” so we decided to dub it like that.

blackbeard_first_old

The development of the code evolved in time. We can connect a part of the infection chain of this Trojan with the threat called Win32/64:Viknok. For both the historic and the current variant of Blackbeard, the complexity of the structure is sketched on this scheme:

blackbeard_structure_and_evolution

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January 9th, 2014

Comparison of Adware in Windows and OS X: Linkular and Genieo

By definition, Adware is a program bundle which renders advertisements in order to generate revenue for its author. In a more strict sense, e.g. for security solutions, it means an application/installer whose nature lies somewhere between a potentially unwanted application and proper malware, like Trojans or Spyware. It might use more or less aggressive methods, starting with tricks and ending with fraud, to achieve its goals to benefit its distributor, while staying as innocent as possible on first sight. We blogged about an adware downloader a year ago.

Now we focus on two selected adware examples: The first is a Windows installer called Linkular and the second is a well-known application called Genieo (with a focus on its OS X version.) Being in the wild for a few months, the detection within AV products reached only partial coverage in both cases, with very similar numbers on VirusTotal (~10-20 %, see Sources below). However, the OS X adware Genieo is additionally flagged by OS X-specific security solutions. Considering maliciousness, the Windows adware is far more dangerous and invasive than the OS X one and also more than other Windows Adware examples we usually see. Here’s the comparison:

property Win32:Linkular MacOs:Genieo
Distribution strategy Advertisement Network unknown
Software Download site coolestmovie.info www.genieo.com
Rank on alexa.com ~4200 ~3000
Masking VLC Player + Addon Flash Player (*)
Payload SpeedUpMyPC; Multiplug; Bitcoinminer;OneStep/BasicServe Codemc; Photo.it; Qtrax(**)
Forced agreement of terms of use YES NO
Change of browser start page YES YES
Persistance YES (of payload) YES
Obfuscation YES (of payload) NO
Digitally signed YES (both installer & payload) YES

(*) masking is not connected with the official site, but some of its distribution partners

(**) related to older installers; not presented anymore

Read more…