Tag Archive for: WannaCry

Hackers use NSA’s leaked EternalBlue exploit to power more malicious payloads

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Hackers are expanding the use of EternalBlue, the leaked NSA hacking exploit that was thrust into the spotlight in May with its initial use in the WannaCry ransomware and Adylkuzz cryptocurrencyminer.

Security researchers have now found threat actors exploiting the vulnerability in Microsoft Server Message Block (SMB) protocol to distribute other malicious payloads including Backdoor.Nitol and Trojan Gh0st RAT.

Backdoor.Nitol is a Trojan horse that opens a backdoor on the infected computer. Gh0st RAT is a remote access trojan that has been making the rounds for years to target Windows machines and is capable of giving attackers full access and control of an infected machine. It has also been used in extensive cyber espionage and data stealing campaigns.

According to security firm FireEye, both the well-known payloads have been previously used in cyberattacks targeting the aerospace and defence industry with Gh0st RAT targeting government agencies and activists as well.

“We observed lab machines vulnerable to the SMB exploit were attacked by a threat actor using the EternalBlue exploit to gain shell access to the machine,” FireEye researchers said in blogpost. “The initial exploit technique used at the SMB level is similar to what we have been seen in WannaCry campaigns.

“However, once a machine is successfully infected, this particular attack opens a shell to write instructions into a VBScript file and then executes it to fetch the payload on another server.”

Researchers said the combination of EternalBlue and VBScript has been used to distribute Gh0st RAT in Singapore and Backdoor.Nitol in the South Asia region.

EternalBlue came as part of the cache of alleged NSA hacking tools released by notorious hacking group Shadow Brokers in April.

Security researchers warned that with EternalBlue exploit now released and available for any threat actors to target, it is likely that it will be used in new sophisticated and more frequent cyberattacks.

“The addition of the EternalBlue exploit to Metasploit has made it easy for threat actors to exploit these vulnerabilities,” FireEye said. “In the coming weeks and months, we expect to see more attackers leveraging these vulnerabilities and to spread such infections with different payloads.

“It is critical that Microsoft Windows users patch their machines and update to the latest software versions as soon as possible.”

IBTimes

Windows 7, not XP, was the reason last week’s WCry worm spread so widely

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Wanacry stats

Eight days ago, the WCry ransomware worm attacked more than 200,000 computers in 150 countries. The outbreak prompted infected hospitals to turn away patients and shut down computers in banks and telecoms. Now that researchers have had time to analyze the self-replicating attack, they’re learning details that shed new and sometimes surprising light on the world’s biggest ransomware attack.

Chief among the revelations: more than 97 percent of infections hit computers running Windows 7, according to attacks seen by antivirus provider Kaspersky Lab. By contrast, infected Windows XP machines were practically non-existent, and those XP PCs that were compromised were likely manually infected by their owners for testing purposes. That’s according to Costin Raiu, director of Kaspersky Lab’s Global Research and Analysis Team, who spoke to Ars.

While the estimates are based only on computers that run Kaspersky software, as opposed to all computers on the Internet, there’s little question Windows 7 was overwhelmingly affected by WCry, which is also known as “WannaCry” and “WannaCrypt.” Security ratings firm BitSight found that 67 percent of infections hit Windows 7, Reuters reported.

The figures challenge the widely repeated perception that the outbreak was largely the result of end users who continued to deploy Windows XP, a Windows version Microsoft decommissioned three years ago. In fact, researchers now say, XP was largely untouched by last week’s worm because PCs crashed before WCry could take hold. Instead, it now appears, the leading contributor to the virally spreading infection were Windows 7 machines that hadn’t installed a critical security patch Microsoft issued in March

The Kaspersky figures are illuminating because they show Windows 7 x64 Edition, which is widely used by large organizations, being infected close to twice as much as Windows 7 versions mostly used in homes and small offices. It’s not clear if that means enterprises are less likely to patch or if there are other explanations.

Also on Friday, researchers published convincing evidence that malicious spam e-mails played no role in initially seeding last week’s ransomware worm. Rather, according to a blog post published by AV provider Malwarebytes, it spread through a mechanism that scanned the Internet for computers with open Server Message Block ports. The worm then used a modified version of “EternalBlue,”—the advanced SMB exploit that was developed by the National Security Agency and leaked by the Shadow Brokers group—to install WCry on vulnerable computers. From there, WCry propagated from vulnerable machine to vulnerable machine inside local networks.

“Developing a well-crafted campaign to identify just… a few thousand vulnerable machines would allow for the widespread distribution of this malware on the scale and speed that we saw with this particular ransomware variant,” Malwarebytes Senior Malware Intelligence Analyst Adam McNeil wrote.

A third revelation: more people than previously known may have been repackaging EternalBlue and other recently leaked NSA exploits in the weeks before the WCry outbreak. Security firm Secdo said on Friday that it unearthed evidence showing that multiple groups exploited the SMB vulnerabilities to install a separate ransomware package, steal login credentials, and to conscript computers into a botnet.

According to Secdo researcher Gil Barak:

Based on these findings, we suspect that the scope of the damage is much greater than previously thought and that there are at least three different groups that have been leveraging the NSA exploit to infect enterprise networks since late April… These attacks demonstrate that many endpoints may still be compromised despite having installed the latest security patch.

Researchers from a separate security firm already showed that criminals were using EternalBlue to make vulnerable computers part of a cryptocurrency mining botnet. A Secdo representative said the attacks the company reported occurred around the same time.

Meanwhile, EternalRocks—a separate self-replicating exploit also developed by the NSA and released in last month’s Shadow Brokers release—is also being repackaged in active attacks. Researcher Miroslav Stampar has details here.

Finally, as reported by Wired on Friday, attackers have been using a knock-off of the powerful Mirai Internet-of-things botnet to attack two servers that are currently preventing WCry and a WCry copycat variant from spreading. Before executing on a vulnerable computer, the worms are programmed to reach out to hardcoded domain names. If the domains respond, the worm aborts without infecting or spreading. Researchers suspect developers intended the mechanism to function as a killswitch they could use to stop the worm, should attackers lose control of it. Should the distributed denial-of-service attacks knock the servers out of commission, there is the possibility the self-replicating infections could start again.

MalwareTech, the pseudonymous researcher who registered the domain that stopped last Friday’s WCry worm, said he’s not concerned about the attacks. He explained to Ars: “at this point, very few samples are actually spreading, so even if the sinkhole were to go offline, the damage would be limited.”

Just to be on the safe side, he has sought the help of an unnamed DDoS mitigation service.

WannaCry Ransomware Decryption Tool Released; Unlock Files Without Paying Ransom

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If your PC has been infected by WannaCry – the ransomware that wreaked havoc across the world last Friday – you might be lucky to get your locked files back without paying the ransom of $300 to the cyber criminals.

Adrien Guinet, a French security researcher from Quarkslab, has discovered a way to retrieve the secret encryption keys used by the WannaCry ransomware for free, which works on Windows XP, Windows 7, Windows Vista, Windows Server 2003 and 2008 operating systems.

WannaCry Ransomware Decryption Keys

The WannaCry’s encryption scheme works by generating a pair of keys on the victim’s computer that rely on prime numbers, a “public” key and a “private” key for encrypting and decrypting the system’s files respectively.

To prevent the victim from accessing the private key and decrypting locked files himself, WannaCry erases the key from the system, leaving no choice for the victims to retrieve the decryption key except paying the ransom to the attacker.

But here’s the kicker: WannaCry “does not erase the prime numbers from memory before freeing the associated memory,” says Guinet.

Based on this finding, Guinet released a WannaCry ransomware decryption tool, named WannaKey, that basically tries to retrieve the two prime numbers, used in the formula to generate encryption keys from memory, and works on Windows XP only.

Note: Below I have also mentioned another tool, dubbed WanaKiwi, that works for Windows XP to Windows 7.

“It does so by searching for them in the wcry.exe process. This is the process that generates the RSA private key. The main issue is that the CryptDestroyKey and CryptReleaseContext does not erase the prime numbers from memory before freeing the associated memory.” says Guinet

So, that means, this method will work only if:

  • The affected computer has not been rebooted after being infected.
  • The associated memory has not been allocated and erased by some other process.

“In order to work, your computer must not have been rebooted after being infected. Please also note that you need some luck for this to work (see below), and so it might not work in every case!,” Guinet says.

“This is not really a mistake from the ransomware authors, as they properly use the Windows Crypto API.”

While WannaKey only pulls prime numbers from the memory of the affected computer, the tool can only be used by those who can use those prime numbers to generate the decryption key manually to decrypt their WannaCry-infected PC’s files.

Good news is that another security researcher, Benjamin Delpy, developed an easy-to-use tool called “WanaKiwi,” based on Guinet’s finding, which simplifies the whole process of the WannaCry-infected file decryption.

All victims have to do is download WanaKiwi tool from Github and run it on their affected Windows computer using the command line (cmd).

WanaKiwi works on Windows XP, Windows 7, Windows Vista, Windows Server 2003 and 2008, confirmed Matt Suiche from security firm Comae Technologies, who has also provided some demonstrations showing how to use WanaKiwi to decrypt your files.

Although the tool won’t work for every user due to its dependencies, still it gives some hope to WannaCry’s victims of getting their locked files back for free even from Windows XP, the aging, largely unsupported version of Microsoft’s operating system.

The Hacker News

‘WannaCry’ Ransomware Attack Spreads to 74 Countries

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A wave of ransomware infections took down a wide swath of UK hospitals and is rapidly moving across the globe.

The so-called Wanna Decryptor ransomware is currently moving like wildfire across 74 countries in more than 45,000 attacks, including a massive takedown of several UK hospitals today.

The number of infections across the world is quickly growing, according to Kaspersky’s Twitter post. So far, some of the countries that have been hit include Britain, Spain, Russia, Taiwan, India, and the Ukraine, according to various reports streaming across the WannaCry Twitter feed.

Security experts say the ransomware attack is exploiting the Server Message Block (SMB) critical vulnerability that was patched by Microsoft on March 14, MS17-010. The 0day exploit, aka ETERNALBLUE, believed to be an NSA exploit tool, initially was leaked by Shadowbrokers, prompting a patch from Microsoft.

“There is nothing comparable to date. This is a massive global ransomware operation, the largest and most effective to date. Unfortunately, not all organizations patched against ETERNALBLUE/shadowbrokers exploits,” said Kurt Baumgartner, principal security researcher, Global Research and Analysis Team (GReAT) for Kaspersky Lab.

According to an Avast blog post, Telefonica in Spain and the National Health Service (NHS) hospitals in England have been hit.

In the UK, a large scale attack hit a number of hospitals across the region, forcing medical staff to re-route emergency patients to other hospitals in the area, according to a report in The Guardian.

The malware struck NHS hospitals around lunch time, with an initial email going out to employees that the email servers were encountering difficulty, followed by clinical and patient systems going down, the Guardian reported. That was followed by a ransom note appearing on employees’ computer screens, demanding $300 in Bitcoins to be paid in three days, otherwise the ransom would double. And if no payment was made after seven days, then the files would be forever lost, according to the report.

The NHS issued an alert and confirmed 16 medical centers had been hit, according to Kaspersky Lab.

This ransom message also appeared in Spain, where telecom giant Telefonica was also targeted, the Guardian noted.

“The suspected syndicated attack is unique in that it’s not targeted at any one industry or region, and is using a particularly nasty form of malware that can move through a corporate network from a single entry point,” says Simon Crosby, co-founder and chief technology officer at Bromium.

“As usual, it’s leveraging a recently patched vulnerability that many have failed to implement in a timely matter,” he says. “As long as the industry continues to play this never ending cat and mouse game of patchwork systems, sophisticated attackers will easily find ways to exploit the public in increasingly large scale attacks such as this.”

How WannaCry Makes You Cry

The ETERNALBLUE exploit tool surfaced on the Internet via the Shadowbrokers’ dump on April 14. Although Microsoft had issued the March patch, many organizations have not yet installed it, according to Kaspersky’s blog post on WannaCry.

The security firm said WannaCry initiates through an SMBv2 remote code execution in Microsoft Windows and then encrypts data with a file extension “.WCRY.” It then drops and executes a decryptor tool that was designed to hit users in multiple countries with a ransom note translated to the appropriate language for that country, according to Kaspersky Lab.

Kaspersky’s Baumgartner describes the attack this way: “It is a worm over SMB and the communications are over TOR, directly to hidden services, so I would not call it a peer-to-peer worm.”

Researchers recommend installing Microsoft’s patch, which closes the affected SMB Server vulnerability used in the WannaCry attack.

For organizations that have older equipment or legacy software, such as hospitals, manufacturing plants, and power plants, deploying a patch can be complicated and disruptive, which may in part explain how a wide swath of NHS hospitals fell victim to WannaCry.

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