New Amazon Ransomware Attack—‘Recovery Impossible’ Without Payment

Update, Jan. 15, 2025: This story, originally published Jan. 13, now includes analysis from security experts, as the nature of the Amazon threat has fully emerged, on how new U.K. government plans to make ransomware payments illegal could impact victims of such cybercrimes, plus further mitigation advice for victims of these attacks.

Ransomware is a cybersecurity threat that just won’t go away. Be it from groups such as those behind the ongoing Play attacks, or kingpins such as LockBit returning from the dead the consequences of falling victim to an attack are laid bare in reports exposing the reach of ransomware across 2024. A new ransomware threat, known as Codefinger, targeting users of Amazon Web Services S3 buckets, has now been confirmed. Here’s what you need to know.

Ongoing Codefinger Ransomware Attacks Target Amazon Cloud Users

A new ransomware campaign targeting Amazon Web Services users by a threat actor known as Codefinger has been confirmed in a Jan. 13 threat intelligence report from Halcyon threat research and intelligence team. The Codefinger attack leverages AWS’s server-side encryption with customer-provided keys, thankfully usually shortened to SSE-C, in order to encrypt data and then demand payment for the symmetric AES-256 keys that are required for it to be successfully decrypted. “This ransomware campaign is particularly dangerous because of SSE-C’s design,” the Halcyon researchers warned, “by integrating directly with AWS’s secure encryption infrastructure and encrypting the data, recovery is impossible without the attacker’s key.”

Halcyon has gone as far as suggesting that Codefinger represents a significant evolution in ransomware capabilities, adding that: “If this spreads quickly, it could pose a systemic threat to organizations using AWS S3 for critical data storage.” I’m not sure I can quite agree that not being able to decrypt data without paying for a key is evolutionary, it’s the basis upon which all ransomware operates, after all, but the use of SSE-C is certainly a novel approach. “Unlike traditional ransomware that encrypts files locally or in transit, this attack integrates directly with AWS’s secure encryption infrastructure, the researchers said, “once encrypted, recovery is impossible without the attacker’s key.”

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All of that said, the attack campaign doesn’t exploit any AWS vulnerability, instead relying upon the age-old tactic of obtaining an AWS customer’s account credentials by hook or by crook.

“This is a great example of where password reuse or sticking with easy-to-guess passwords, along with no two-factor authentication, will come back to bite admin,” Darren James, a senior product manager at Specops Software, said. If people had ensured that they were using different passwords for all systems as well as enabling strong, phishing-resistant 2FA wherever possible, James said, “this latest ransomware attack could have been avoided. On the upside, at least SSE-C is a strong encryption method, but it is not good to see it used against the good guys rather than for them.”

Amazon Cloud Codefinger Ransomware Attack Flow

The Halcyon report reported that the attack flow used by Codefinger is as follows:

• Identify vulnerable AWS keys using publicly disclosed, or previously compromised, keys.
• Encrypt files using SSE-C utilizing an AES-256 encryption key that is generated and stored locally.
• Set lifecycle policies for file deletion, marking these at 7 days using the S3 Object Lifecycle Management application programming interface to add urgency to the ransom demand.
• Deposit a ransom note in each affected directory, warning that any changes to account permissions or files will end negotiations.

Recovery Impossible Amazon Ransomware Highlights Difficulties In Making Ransom Payments Illegal

As news of plans by the U.K. Home Office to make ransomware payments illegal for some victims, specifically national infrastructure companies and services, security experts have come forward with their opinions on such a move. Given that the Amazon attack brings the impossible to recover without paying a ransom issue to the incident response table, such laws are far from straightforward. "The topic of ransomware payments is one which is fiercely debated,” Javvad Malik, lead security awareness advocate at KnowBe4, said, “while almost everyone agrees that paying ransomware is not desirable and organizations don't want to contribute towards cybercrime or state-sponsored activities.” But mandating by law that ransoms are illegal is quite the thing. “People will typically want to do the right thing,” Malik said, “no executives willingly set up their organization to become a victim of ransomware, but when it does strike, and pressure begins to mount from shareholders, customers, and the government, the temptation of paying the ransom continues to grow, unless alternative ways out are provided." This is where the government should be working alongside organizations to minimize the disruption from ransomware, Malik concluded, “or at the very least offering extensive guidance on how to prevent, detect, respond, and recover from ransomware attacks.”

Dr. Darren Williams, CEO and founder of BlackFog, pointed out that ransomware gangs, like most criminals, are “highly motivated by profit and tend to gravitate towards targets that are more likely to pay up.” Not that paying up is any guarantee, as Williams said: “At the end of the day, you are negotiating with criminals who are unlikely to uphold their end of the deal, and in many cases, they go further than leaking stolen data by targeting the same victim a short time later.”

Jochen Michels is the European head of public affairs at Kaspersky and argued that though paying ransoms does perpetuate the cycle of crime, there are numerous no-win scenarios to consider. “Paying ransoms to cybercriminals perpetuates the cycle of crime and offers no guarantee of resolution, which is why we advise against it,” Michels said, adding that there are safeguarding industry initiatives in place, like the Kaspersky No Ransom initiative, which aim to provide victims with solutions to recover their data without giving in to criminal demands. Unfortunately, these initiatives that provide free ransomware decryptors would be of little use to victims of the Amazon “recovery impossible” ransomware attack due to the use of SSE-C keys. No wonder, then, that Michels said, “In certain high-stakes scenarios, the decision to pay or not to pay becomes far more complex.” This highlights the urgent need for government safeguards to support victims who face no-win situations, Michels said, “such measures could include financial assistance for recovery efforts, access to decryption tools, or even indemnities in cases where paying the ransom is deemed the only viable option.”

Meanwhile, Jamie Akhtar, co-founder and CEO of CyberSmart, also said that while the sentiment of the proposed U.K. government policy should be applauded, a note of caution needs to be sounded. “This approach will only work if organizations have the cybersecurity measures in place – such as regular backups and properly siloed data – to get back on their feet quickly, even if a ransom isn’t paid,” Akhtar warned. Many organizations, of course, don’t have these measures in place, or at least not to the degree needed and, as a result, have little choice but to pay the ransom or face reputational or financial ruin. “A step like this needs to be taken in conjunction with a broader commitment to improve cybersecurity practice,” Akhtar concluded, “otherwise, it risks causing a lot of collateral damage, particularly to the small businesses who make up the backbone of our economy."

Mike Kiser, director of strategy and standards at SailPoint, however, was much clearer when he said, “ransom payments should be banned: increasing payouts mean a corresponding rise in malicious activity.” Yet all is not as straightforward as that may sound, as Kiser admitted: “As soon as laws are passed to ban ransom payments, an underground market is likely to arrive – resulting in a hidden economic system.” Who is then held responsible for violating laws, Kiser questioned, “is it the corporate entity or the fault of the security executive?”

Amazon Statement Regarding The Codefinger Ransomware Attacks

An Amazon Web Services spokesperson provided the following statement: “AWS helps customers secure their cloud resources through a shared responsibility model. Anytime AWS is aware of exposed keys, we notify the affected customers. We also thoroughly investigate all reports of exposed keys and quickly take any necessary actions, such as applying quarantine policies to minimize risks for customers without disrupting their IT environment. We encourage all customers to follow security, identity, and compliance best practices. In the event a customer suspects they may have exposed their credentials, they can start by following the steps listed in this post. As always, customers can contact AWS Support with any questions or concerns about the security of their account.”