Protecting over 200 million PCs, Macs, & Mobiles – more than any other antivirus

Archive

Archive for the ‘analyses’ Category
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

Read more…

January 22nd, 2014

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

1608606_777513882262041_947320490_n

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

Read more…

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…

December 11th, 2013

Browser Ransomware tricks revealed

It’s not surprising that scared people are the most vulnerable to attacker’s traps, and there is no reason to think it will work differently with computer users. Using this psychology, cybercrooks show an unaware victim an alert page claiming to have found that banned pornography was viewed or stored on their computer. The message goes on to say their computer is blocked, all their data is encrypted, and they will be sent to court in 48 hours unless they pay a fine. This is basically how ‘Ransomware’ works – scare tactics with a convenient way to buy yourself out of the predicament at the end.

Ransomware page

When we look closer at the scam, we find that the Ransomware is focused only on the victim’s browser and fortunately, not as they claim, on the data stored inside the victim’s computer. Here are several points that work together to scare the victim:

  • The headline of the webpage: “FBI. ATTENTION! Your browser has been blocked…”. This is the part of the attack that tries to scare visitors as much as possible.
  • The name of the page, “gov.cybercrimescenter.com”, tries to convince visitors they are on a legitimate website which belongs to the government.
  • A countdown timer starts on 48 hours and counts down the time before “legal steps” starts.

These points try to rush panicked victims into paying the requested money as soon as possible without time to think. But it’s better to take a deep breath before reacting. You know you didn’t watch the movies mentioned on the page, and of course, you didn’t store illegal files. Do you really think that upon identifying a child pornographer, that the government will tell them to pay a small amount of money as a fine and let them go?

Read more…

Comments off
November 21st, 2013

Ransomware shocks its victims by displaying child pornography pictures

In our blog, we wrote several times about various types of Ransomware, most recently about CryptoLocker. In most cases, ransomware has pretended to be a program installed into a victim’s computer by the police. Because of some alleged suspicious activities found on the user’s computer, ransomware blocks the user from using the computer and demands a ransom to unlock the machine or files.

Different ransomware families have different graphics and skins, usually showing intimidating images of handcuffs, logos of various government and law enforcement organizations, policemen performing inspections, government officials, etc… You can read some of our previous analyses on our blog – Reveton, Lyposit, Urausy – are the most prolific examples of such ransomware.

In this blog post, we will look at the functionally of the same type of ransomware, but one which displays more annoying and disturbing photos. After showing the message saying, “Your computer has been suspended on the grounds of viewing illegal content,” accompanied with the current IP address, name of internet service provider (ISP) and the geographical location, it displays several pictures of child pornography!
01_censored Read more…

Comments off
November 20th, 2013

Fallout from Nuclear Pack exploit kit highly toxic for Windows machines

In recent days, the avast! Virus Lab has observed a high activity of malware distributed through exploit kits. Most cases of infection are small websites which usually provide adult entertainment, but there was also news about one of the top 300 visited websites being infected.

Infection chains ended dropping a final payload in a form of an executable file with a constant, not wide-spread name like 1SKKKKKKK.exe. After a closer look, we found that this filename is shared among aggressive malware threats – banking Trojans like Win32:Citadel, Win32:Shylock/Caphaw, Win32:Ranbyus, Win32:Spyeye; stealthy infostealers like Win32:Neurevt (a.k.a. BetaBot), Win32:Gamarue, Win32:Cridex, Win32:Fareit; and even file infectors like Win32/64:Expiro(infected dbghlp.exe).

We received ~1000 unique samples in the last 10 days which possess suspicious filenames, polymorphically covering ~30 malware families with many different packers. Researching infected iframes in our databases, we discovered an infection chain which leads to a payload with a strange name that looks like this:

1skkkkk_scheme

Read more…

October 22nd, 2013

Win32:Reveton-XY [Trj] saves hundreds of computers worldwide and cybercriminals know it!!!

It has been more than a year, since we last time reported about Reveton lock screen family. The group behind this ransomware is still very active and supplies new versions of their ransomware regularly.

reveton-xy_000-mainpicture Read more…

Categories: analyses, Virus Lab Tags: ,