WannaCry

WannaCry is a famous Ransomware that utilizes the EternalBlue exploit. This malware is known for infecting at least 200,000 computers worldwide and it continues to be an active and dangerous threat.

Type
Ransomware
Origin
Likely North Korea
First seen
12 May, 2017
Last seen
17 January, 2020
Also known as
WCry
WanaCryptor
Global rank
20
Week rank
11
Month rank
14
IOCs
93

What is WannaCry ransomware?

WannaCry which is sometimes also called WCry or WanaCryptor is a ransomware malware, meaning that it encrypts files of its victims and demands a payment to restore the stolen information, usually in bitcoin with ransom amounts ranging from $300 to $600 equivalents.

The virus can be described as ransomware with worm functionality, since it is capable of spreading itself within infected networks using the EternalBlue exploit. Additionally, the virus uses DoublePulsar exploit to upload and execute a copy of itself to a new machine.

Once WannaCry makes its way into a target computer, it begins its malicious activity by checking for a hardcoded kill switch domain - either fferfsodp9ifjaposdfjhgosurijfaewrwergwea[.]com or iuqerfsodp9ifjaposdfjhgosurijfaewrwergwea[.]com. In an event, if one is found, the malware stops the execution. However, if a kill switch domain isn’t found, the ransomware encrypts files on the machine, following which an attempt to exploit the SMB vulnerability takes place. This is done in an effort to spread the virus over to other random PCs and all those connected in a local network. After encryption is completed, a ransom note is displayed to the user and the attackers demand $300 to be paid in a 3-day timespan. If the victim resists the ransom amount rises to $600 to be paid in 7 days. The payments are directed to multiple hardcoded bitcoin addresses. Typical for a cryptocurrency, anybody can check their balances and transaction history but the true owner of such a wallet can not be traced.

General description of WannaCry

The first time WannaCry malware was seen in the wild was as a part of a devastating worldwide attack that took place in May 2017. The attack utilized an EternalBlue exploit, which was believed to have been developed by the American NSA and leaked by a cybergang known under the allies “The Shadow Brokers”.

The exploit leveraged a vulnerability in the Windows operating systems and while a patch fixing the issue was released quickly by the company, many individuals and organizations who didn’t promptly update their computers became victims of this attack.

By some broad estimations, over 200,000 computers worldwide were infected by WannaCry within those few days that the attack was ongoing. A fix of the EternalBlue exploit along with the discovery of the “kill switch” that allowed to stop the execution of the malware were the two main contributions that helped to slow down this malicious campaign. However, by the time the attack came to an end total damage amounted to billions of dollars and victims from over 150 countries were affected.

A campaign of such scale raised international investigation of the highest level aimed to find out who was behind the outbreak. Experts investigated the ransom notes to find out that they were most likely written by hand and the writers seemed to be fluent in Chinese and English, as was suggested by the linguistics analysis. Further investigation suggested that the native language of the writer was Chinese since two versions of ransom note were composed in this language - on in Simplified and one in Traditional Chinese. Furthermore, some typos in the notes lead researchers to believe that a Chinese input system was used for typing, as mistakes like those present could not have been easily made using any other form of input.

It should be noted, that in total the ransom note was written in 28 languages including both Chinese variations. However, for most of those languages, a machine translation was used.

The FBI then uncovered that Hangul fonts were installed on the machine that was used to compose the ransom notes. Hangul is an alphabet and a writing system used in the South as well as in North Korea. Further analysis of the language files metadata displayed that the computer was set to a Korean Timezone.

Upon further review of malware samples, security researchers from Google, Kaspersky Lab, and Symantec concluded that the code of WannaCry exhibited similarities to other malware used in the attacks against Sony Pictures and a Bangladesh bank. Those attacks were carried out by a so-called Lazarus Group, members of which were linked to North Korea.

Of course, this evidence was not conclusive as other groups could have simply reused some of the code produced by the Lazarus Group. What’s more, the use of such code could have been intentional in order to mislead the investigators and put the blame on other cybercriminals.

However, a liked memo from NSA as well as findings made by UK's National Cyber Security Centre also pointed at North Korea as the country from which the attack originated. The United States Government subsequently proceeded to formally declare North Korea to be the attack origin.

In foresight, despite the fact that the WannaCry attack had a truly unprecedented scale, its impact is considered relatively low, compared to other ransomware. The aftermath could have been much worse if it was not for the discovery of the kill switch. Furthermore, the virus could have been targeted at high-level infrastructures like the transport control systems and nuclear power plants. Had this been the case, some experts estimate possible losses in excess of hundreds of millions of dollars.

Talking about the actual malware - WannaCry comes in the form of a dropper which holds various components as a ZIP archive which is protected by a password. This archive is being unpacked during the execution using a hardcoded password and dropped into a directory from which it was executed.

WannaCry ransomware uses two encryption methods during its execution: RSA and AES-128-CBC. To confuse the researchers the encryption scenario that is contained in a t.wnry file is actually encrypted in exactly the same way that the malware uses to encrypt data on an infected machine. A custom loader is used to load the module into memory, so the un-encrypted version of the file never has to be recorded on the victim’s hard drive.

Upon the start of the execution process, the malware uses an RSA key to unpack the t.wnry file and decrypt it. Then a new RSA key will be generated and sent to a C&C server, while a duplicate of a public key is being saved on the infected machine.

This is where the encryption process begins and the virus searches the infected machine for files with supported extensions. Then, a 128 bit AES key is created per every single file that was selected for encryption and encrypted using the RSA key created earlier. RSA-encrypted AES key is placed in a header of an encrypted file. After this, the malware uses the AES key to encrypt data in the file.

The encryption is performed in such a way that it is virtually impossible to restore the lost data without access to the private key, that is stored in the control server. This means that for a victim the only way to regain access to their information is to fulfill the ransom demand, made by the attackers.

For persistence, WannaCry writes itself in the autorun keys in the registry and creates a couple of services.

WannaCry malware analysis

A video simulation recorded on ANY.RUN allows us to examine the lifecycle of WannaCry.

wannacry execution process graph

Figure 1: Process graph generated by ANY.RUN allows us to see the main processes of Dridex execution.

text report of the wannacry analysis

Figure 2: Displays the customizable text report generated by ANY.RUN.

How does WannaCry infect?

Besides being distributed by malicious spam campaigns, WannaCry ransomware uses a more interesting way to infect devices - it utilizes an operating system vulnerability as the initial attack vector. Once the malware successfully leverages an exploit and makes its way into a machine, it will scan the IP addresses in an attempt to infect connected devices through the SMB vulnerability on port 445/TCP. This vulnerability has CVE ID 2017-0144 and also known as MS17-010 EternalBlue.

All devices in a local network exhibiting potential vulnerability will also be infected.

WannaCry execution process

First of all, after running, WannaCry sends an HTTP GET request to hardcoded domains and stops execution if the request is successful. Although WannaCry execution process is pretty straightforward, it's pursuing not just the goal of encrypting files on the infected machine, but it's also trying to infect as many nearby machines as it can. To do so, the ransomware scans all machines with port 445 being open and if the connection is made, tries to exploit the SMBv1 vulnerability (EternalBlue). On the local system, WannaCry executable file extracts and installs binary and configuration files from its resource section. It also hides extract directory, modifies security descriptors, creates an encryption key, deletes shadow copies and so on. After all these steps, WannaCry encrypts the user's data and sets the wallpaper to a ransom note. In addition, a @[email protected] executable file is being started to provide information about countdown and payment method to a victim.

workstation desktop after wannacry infection

Figure 3: A Desktop of a system infected by WannaCry

Prevention of WannaCry attacks

In order to prevent potential WannaCry attacks, users should install security patches created by Microsoft in response to the original incident. Today, early versions of WannaCry won't work because their killswitch is still active.

The patch code for this security update is MS-17-010 and the update is available even for Windows XP; it was the first update to this operating system issued by Microsoft in 3 years.

How to get more WannyCry data using ANY.RUN?

Since crooks behind WannyCry offer decryption of three images for free you can use the interactivity of ANY.RUN to take additional steps in your analysis. Open the website specified in a ransom note in the browser and follow all steps to decrypt images to get a bigger picture of a ransomware infection process.

wannacry ransom note Figure 4: Wannacry ransom note

Conclusion

WannaCry is undoubtedly one of the most destructive malware ever used by cyberattacks. The first malicious campaign utilizing this dangerous virus had a truly unprecedented scale.

Thankfully, due to outstanding work done by cybersecurity professionals, the attack was contained in just a few days by finding an effective kill switch and patching the vulnerability in the Microsoft operating systems that the ransomware was targeting. However, even despite such quick reaction times made by cybersecurity professionals all around the world, billions of dollars were lost by victims all across the world.

To prevent devastating cyber attacks such as the one performed using the WannaCry virus, researchers should learn as much as possible about the existing malware samples and analyze their code. This task is greatly simplified with the use of interactive sandboxes like ANY.RUN, which allows users to influence the simulation in real-time in order to get the best results.

IOCs

IP addresses
192.168.100.203
104.17.244.81
50.63.202.62
104.16.173.80
50.63.202.51
192.168.100.4
192.168.100.172
192.164.44.4
Hashes
ed01ebfbc9eb5bbea545af4d01bf5f1071661840480439c6e5babe8e080e41aa
dbf3890b782ac04136c3336814eef97e3c0f4133f9592e882c131c179161b27b
33ca2a6adcf4168a616328cc161a431fa3f8908d25f9bd8ba71fe04837ea15fc
24d004a104d4d54034dbcffc2a4b19a11f39008a575aa614ea04703480b1022c
bde526ed27ce0630401ad24794014b68e32de413de6bc7f37319e4cc4afa283d
cb7d887d12130b1ce696c5c0465f7a61f27176882b7a9005724b08f319fef4a5
0b1d91f4dc6ec880c788996c4baf00626afd49eceb92a66ced506e0f3a125679
e76a89ab31e68bbcb1eeaf4a95c26e1219123395b5d79aba2f5a444cb6ca1231
74d72f5f488bd3c2e28322c8997d44ac61ee3ccc49b7c42220472633af95c0c0
45f1fe890d4bf3866cedcd054a392d94b6758524501a82f8d89d5e2970b67286
2b3a13c72b6fe9e76f8841ede29c91a5d5a8195ef369cb5f3c8c306e17b5c4a6
4097c2a769f488c2b92b3c35b6dbf4f1484ed4e56ee4561d144108537424a55c
fc8de97d20559d073b34a7dd853000671f2d30953e5fae699702569ed74b8d0f
55bc52ead4c668b4dad978bebd80821a68eccd36b3927072a5d113cd5d79a27a
719b7732a38567fd18c357eb99e2561a0d0dfc0ae3c6806f3e9e44d1a38de512
79d8e622960e141efe1d9399707a3a68c64c528dc7b0f7c129c4b0a0e4ea6676
b895ca15792b7d00aa2f06953f7bc2e2d0adaa823b6b71698b6f3080a64d1a1a
aea79945c0f2f60de43193e1973fd30485b81d06f3397d397cb02986b31e30d9
c365ddaa345cfcaff3d629505572a484cff5221933d68e4a52130b8bb7badaf9
0bd4260a5bcad45db29c528b2eeb1dbb0ec08d37992d8083f717f9117d817761
Domains
www.bonesinbroth.com
ayc0zsm69431gfebd.xyz
thuocnam.tk
majul.com
m-onetrading-jp.com
krupskaya.com
isns.net
nvisionsigns.com
www.iuqerfsodp9ifjaposdfjhgosurijfaewrwergwea.com
iuqerfsodp9ifjaposdfjhgosurijfaewrwergwea.com
www.aolmailcustomerservice.online
www.bootcamp.tools
www.newexsports.info
aslovel.com
www.eva.legal
huagg3.info
ip-50-63-202-62.ip.secureserver.net
www.giogio.store
www.tcg.properties
www.confluent.solutions

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