I recently spoke at GrrCon 2018 about how ransomware actually implement key management models by abusing the resident CryptoAPI on host systems. This 25 minute talk goes deep into explaining what the CryptoAPI entails on a Windows system, what DLLs the ransomware imports, what functions from these DLLs are used by the ransomware, and how Cryptographic Service Providers (CSPs) come into the picture.
This talk also demonstrates the concepts by taking the example of the infamous "NotPetya" ransomware. We reverse engineer the NotPeya malware in IDA disassembler and discuss the cryptographic functions being imported from DLLs on Windows.
Ransomware such as WannaCry and Petya have been heavily focused upon in the news but are their cryptographic models different from predecessors? Key management is crucial to these cryptoviral extortions and for convenience, they harness the power of resident Crypto APIs available on host. Simply stated, they command victim’s resources to lock victim’s resources. In this talk, we examine popular key management models deployed in infamous cryptovirii with the ultimate objective of providing a deeper comprehension of exactly how resident APIs are being used against users. On a Windows host, CryptoAPI (CAPI) provides cryptographic services to applications. CSPs are sets of DLLs that are associated with CAPI implementing cryptographic functions such as CryptAcquireContext, CryptGenKey, CryptEncrypt, CryptImportKey, CryptExportKey, CryptDestroyKey. In Windows Vista and later, CNG replaces CAPI and the ransomware menace persists. We explain cryptographic functions exploited by several ransomware families and explore answers to crucial questions such as how and where the encryption key is generated, where it is stored, how it is protected while encrypting user data, and how it is securely purged. We provide graphical representations combined with pseudo-codes embodying real-world Crypto API function calls pertaining to key management in ransomware. This talk delves deep into key management in present-day ransomware and is a direct result of real-world case studies of highly virulent infections. Dissections will be shown to back up the arguments.
Right now, your computer might be using its memory and processor power – and your electricity – to generate money for someone else, without you ever knowing. It’s called “cryptojacking,” and it is an offshoot of the rising popularity of cryptocurrencies like bitcoin.
Instead of minting coins or printing paper money, creating new units of cryptocurrencies, which is called “mining,” involves performing complex mathematical calculations. These intentionally difficult calculations securely record transactions among people using the cryptocurrency and provide an objective record of the “order” in which transactions are conducted.
The user who successfully completes each calculation gets a reward in the form of a tiny amount of that cryptocurrency. That helps offset the main costs of mining, which involve buying advanced computer processors and paying for electricity to run them. It is not surprising that enterprising cryptocurrency enthusiasts have found a way to increase their profits, mining currency for themselves by using other people’s processing and electrical power.
Our security research group at Michigan State University is presently focused on researching ransomware and cryptojacking – the two biggest threats to user security in 2018. Our preliminary web crawl identified 212 websites involved in cryptojacking.
Source code of a cryptojacking website, with a box around the text telling the software where to credit any cryptocurrency earnings.Screenshot by Pranshu Bajpai, CC BY-ND
The mining script can be very small – just a few lines of text that download a small program from a web server, activate it on the user’s own browser and tell the program where to credit any mined cryptocurrency. The user’s computer and electricity do all the work, and the person who wrote the code gets all the proceeds. The computer’s owner may never even realize what’s going on.
Is all cryptocurrency mining bad?
There are legitimate purposes for this sort of embedded cryptocurrency mining – if it is disclosed to users rather than happening secretly. Salon, for example, is asking its visitors to help provide financial support for the site in one of two ways: Either allow the site to display advertising, for which Salon gets paid, or let the site conduct cryptocurrency mining while reading its articles. That’s a case when the site is making very clear to users what it’s doing, including the effect on their computers’ performance, so there is not a problem. More recently, a UNICEF charity allows people to donate their computer’s processing power to mine cryptocurrency.
However, many sites do not let users know what is happening, so they are engaging in cryptojacking. Our initial analysis indicates that many sites with cryptojacking software are engaged in other dubious practices: Some of them are classified by internet security firm FortiGuard as “malicious websites,” known to be homes for destructive and malicious software. Other cryptojacking sites were classified as “pornography” sites, many of which appeared to be hosting or indexing potentially illegal pornographic content.
The problem is so severe that Google recently announced it would ban all extensions that involved cryptocurrency mining from its Chrome browser – regardless of whether the mining was done openly or in secret.
The longer a person stays on a cryptojacked website, the more cryptocurrency their computer will mine. The most successful cryptojacking efforts are on streaming media sites, because they have lots of visitors who stay a long time. While legitimate streaming websites such as YouTube and Netflix are safe for users, some sites that host pirated videos are targeting visitors for cryptojacking.
Other sites extend a user’s apparent visit time by opening a tiny additional browser window and placing it in a hard-to-spot part of the screen, say, behind the taskbar. So even after a user closes the original window, the site stays connected and continues to mine cryptocurrency.
What harm does cryptojacking do?
The amount of electricity a computer uses depends on what it’s doing. Mining is very processor-intensive – and that activity requires more power. So a laptop’s battery will drain faster if it’s mining, like when it’s displaying a 4K video or handling a 3D rendering.
Similarly, a desktop computer will draw more power from the wall, both to power the processor and to run fans to prevent the machine from overheating. And even with proper cooling, the increased heat can take its own toll over the long term, damaging hardware and slowing down the computer.
This harms not only individuals whose computers are hijacked for cryptocurrency mining, but also universities, companies and other large organizations. A large number of cryptojacked machinesacross an institution can consume substantial amounts of electricity and damage large numbers of computers.
Protecting against cryptojacking
Users may be able to recognize cryptojacking on their own. Because it involves increasing processor activity, the computer’s temperature can climb – and the computer’s fan may activate or run more quickly in an attempt to cool things down.
People who are concerned their computers may have been subjected to cryptojacking should run an up-to-date antivirus program. While cryptojacking scripts are not necessarily actual computer viruses, most antivirus software packages also check for other types of malicious software. That usually includes identifying and blocking mining malware and even browser-based mining scripts.
Selenium seems to be great for browser automation and has support for multiple programming languages, including my favorite -- Python. I decided to test it on Kali Linux and faced certain issues. So I resolved them one at a time and I am logging the procedure here.
Installing Selenium
First, we need to install the Selenium module in Python using 'pip install'. This is simply:
apt-get install python-pip pip install selenium
This should install the latest version of Selenium module. Test it by going to the Python command line and importing the module:
from selenium import webdriver
This works. What does not work is following test code:
It fails saying: webdriverexception: 'geckodriver' executable needs to be in path.
To resolve this, we need to install 'geckodriver'.
Installing Geckodriver
Grab 'geckodriver' from its Github here: https://github.com/mozilla/geckodriver/releases
I grabbed Linux64 bit version since I am running Kali Linux 64 bit. Unpack the archive and make the geckodriver executable and copy it so that Python can find it:
The problem here is that the latest version of Selenium that we installed cannotinterface with the older version of Firefox that comes bundled with Kali Linux. I do have the latest version of Firefox downloaded and unzipped.
Loading the correct Firefox version
So now we point Selenium to use this latest binary of Firefox instead:
from selenium.webdriver.firefox.firefox_binary import FirefoxBinary binary = FirefoxBinary('/root/Downloads/firefox/firefox') driver = webdriver.Firefox(firefox_binary=binary)
Of course, you need to ensure that paths are correct pertaining to your system and where you downloaded and unzipped Firefox. At this point, we can get this Python script to open a webpage for us:
from selenium import webdriver from selenium.webdriver.firefox.firefox_binary import FirefoxBinary binary = FirefoxBinary('/root/Downloads/firefox/firefox') driver = webdriver.Firefox(firefox_binary=binary) driver.get('https://www.lifeofpentester.blogspot.com')
#insert time.sleep() here driver.close()
So now that we have some browser automation going, I will post more results and scripts such as logging into web forms using automated Selenium scripts when I find time. Let me know in comments if this solution worked for you.
Cryptocurrency mining can be a legitimate source of revenue – but not when done secretly or by hijacking others’ computers to do the work and having them pay the resulting financial costs.