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SHA-1 collision attacks are now actually practical and a looming danger

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Attacks on the SHA-1 hashing algorithm just got a lot more dangerous last week with the discovery of the first-ever “chosen-prefix collision attack,” a more practical version of the SHA-1 collision attack first carried out by Google two years ago.

What this means is that SHA-1 collision attacks can now be carried out with custom inputs, and they’re not just accidental mishaps anymore, allowing attackers to target certain files to duplicate and forge.

SHA-1 collision attacks

The SHA-1 hashing function was theoretically broken in 2005; however, the first successful collision attack in the real world was carried out in 2017.

Two years ago, academics from Google and CWI produced two files that had the same SHA-1 hash, in the world’s first ever SHA-1 collision attack –known as “SHAttered.”

Cryptographers predicted SHA-1 would be broken in a real-world scenario, but the SHAttered research came three years earlier than they expected, and also cost only $110,000 to execute using cloud-rented computing power, far less than what people thought it might cost.

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Image: Google

SHA-1 chosen-prefix attacks

But last week, a team of academics from France and Singapore has taken the SHAttered research one step further by demonstrating the first-ever SHA-1 “chosen-prefix” collision attack, in a new research paper titled “From Collisions to Chosen-Prefix Collisions – Application to Full SHA-1.”

“Finding a practical collision attack breaks the hash function badly of course, but the actual damage that can be done with such a collision is somewhat limited as the attacker will have little to no control on the actual data that collides,” Thomas Peyrin, one of the researcher told ZDNet via email over the weekend.

“A much more interesting attack is to find a so-called ‘chosen-prefix collision,’ where the attacker can freely choose the prefix for the two colliding messages. Such collisions change everything in terms of threat because you can now consider having collisions with meaningful data inside (like names or identities in a digital certificate, etc).”

What this means is that SHA-1 collision attacks aren’t a game of roulette anymore, and now, threat actors can forge any SHA-1-signed documents they want, ranging from business documents to TLS certificates.

SHA-1 chosen-prefix collision attacks are now also cheap

But the work of Peyrin and his colleague –Gaetan Leurent– have done goes far beyond than proving SHA-1 chosen-prefix collision attacks are theoretically possible.

They also showed that such attacks are now cheap and in the budget of cybercrime and nation-state attackers.

“These chosen-prefix collisions are believed to be much harder to find than classical collisions. For SHA-1, the best previous search method required 2^77 SHA-1 evaluations, which remained out of reach in practice,” Peyrin told ZDNet.

“The novelty in our article is that we explain how to drastically reduce the cost of finding chosen-prefix collisions for SHA-1, down to almost the same cost as finding a classical collision,” he said.

“We are currently working on further improvements (unpublished yet), and we evaluate now that one can find a chosen-prefix collision for SHA-1 with a budget of less than $100,000, which is really practical.”

This is about the same cost as the original SHAttered research, yet, this version of the attack is what attackers would likely use if they’d ever want to attack SHA-1-protected data.

“We have tested all subcomponents of the attack, but we have not tried to compute a chosen-prefix collision example,” Peyrin said.

“Our initial estimations were $1 million to compute the chosen-prefix collision, which is an amount of money we simply don’t have. Thanks to our latest improvements, the cost went down below $100,000 and we are currently working on computing the first chosen-prefix collision for SHA-1.

“Hopefully, we will be able to announce new results soon,” the researcher said.

Moving away from SHA-1

Browser vendors have long ago started deprecating support for SHA-1-signed TLS traffic inside their products; however, other applications still rely on it.

“There are still many users with older browsers and many protocols and software that allow SHA-1 signatures. Concretely, it is still possible to buy an SHA-1 certificate from a trusted CA, and many email clients accept an SHA-1 certificate when opening a TLS connection,” Peyrin told us.

“SHA-1 is also widely supported to authenticate TLS and IKE handshake messages. Now, what protocol can be attacked and to what extent is hard to tell at the moment, because it needs careful scrutiny of the inner working of the protocol and how the digital signatures / certificates are used, etc..

“However, what we can say is that our attack put at possible risk products using digital signatures, or certificates based on SHA-1,” Peyrin said.

“The take-home message should really be that using SHA-1 for digital
signatures or certificates is very dangerous, and should not be allowed. People doing so are strongly advised to change to SHA-2 or SHA-3 now.”

What to use?

“The attacks against SHA-1 are only going to get better,” Scott Arciszewski, Chief Development Officer at Paragon Initiative Enterprises, and a leading cryptographer, told ZDNet in a separate email.

“Everyone should switch to (in order of preference):

  • BLAKE2b / BLAKE2s
  • SHA-512/256
  • SHA3-256
  • SHA-384
  • Any other SHA2-family hash function as a last resort

“…unless they’re storing passwords! In which case, they should switch to (in order of preference):

  • Argon2id with memory >= 32MiB, >= 2 rounds, and >= 2 parallelism
  • scrypt / yescrypt with memory >= 32 MiB, >= 4 rounds, and >= 1 parellelism
  • bcrypt (for PHP devs, password_hash() and password_verify() does the trick)
  • PBKDF2-SHA512 with 85,000 iterations as a last resort

“But SHA1 should no longer be used anymore. No excuses,” Arciszewski said.

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GigaOm Radar for DDoS Protection

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With ransomware getting all the news coverage when it comes to internet threats, it is easy to lose sight of distributed denial of service (DDoS) attacks even as these attacks become more frequent and aggressive. In fact, the two threats have recently been combined in a DDoS ransom attack, in which a company is hit with a DDoS and then a ransom demanded in exchange for not launching a larger DDoS. Clearly, a solid mechanism for thwarting such attacks is needed, and that is exactly what a good DDoS protection product will include. This will allow users, both staff and customers, to access their applications with no indication that a DDoS attack is underway. To achieve this, the DDoS protection product needs to know about your applications and, most importantly, have the capability to absorb the massive bandwidth generated by botnet attacks.

All the DDoS protection vendors we evaluated have a cloud-service element in their products. The scale-out nature of cloud platforms is the right response to the scale-out nature of DDoS attacks using botnets, thousands of compromised computers, and/or embedded devices. A DDoS protection network that is larger, faster, and more distributed will defend better against larger DDoS attacks.

Two public cloud platforms we review have their own DDoS protection, both providing it for applications running on their public cloud and offering only cloud-based protection. We also look at two content delivery networks (CDNs) that offer only cloud-based protection but also have a large network of locations for distributed protection. Many of the other vendors offer both on-premises and cloud-based services that are integrated to provide unified protection against the various attack vectors that target the network and application layers.

Some of the vendors have been protecting applications since the early days of the commercial internet. These vendors tend to have products with strong on-premises protection and integration with a web application firewall or application delivery capabilities. These companies may not have developed their cloud-based protections as fully as the born-in-the-cloud DDoS vendors.

In the end, you need a DDoS protection platform equal to the DDoS threat that faces your business, keeping in mind that such threats are on the rise.

How to Read this Report

This GigaOm report is one of a series of documents that helps IT organizations assess competing solutions in the context of well-defined features and criteria. For a fuller understanding consider reviewing the following reports:

Key Criteria report: A detailed market sector analysis that assesses the impact that key product features and criteria have on top-line solution characteristics—such as scalability, performance, and TCO—that drive purchase decisions.

GigaOm Radar report: A forward-looking analysis that plots the relative value and progression of vendor solutions along multiple axes based on strategy and execution. The Radar report includes a breakdown of each vendor’s offering in the sector.

Solution Profile: An in-depth vendor analysis that builds on the framework developed in the Key Criteria and Radar reports to assess a company’s engagement within a technology sector. This analysis includes forward-looking guidance around both strategy and product.

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GigaOm Radar for Security Information and Event Management (SIEM) Solutions

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The security information and event management (SIEM) solution space is mature and competitive. Most vendors have had well over a decade to refine their products, and the differentiation among basic SIEM functions is fairly small.

In response, SIEM vendors are developing advanced platforms that ingest more data, provide greater context, and deploy machine learning and automation capabilities to augment security analysts’ efforts. These solutions deliver value by giving security analysts deeper and broader visibility into complex infrastructures, increasing efficiency and decreasing the time to detection and time to respond.

Vendors offer SIEM solutions in a variety of forms, such as on-premises appliances, software installed in the customers’ on-premises or cloud environments, and cloud hosted SIEM-as-a-Service. Many vendors have developed multi-tenant SIEM solutions for large enterprises or for managed security service providers. Customers often find SIEM solutions challenging to deploy, maintain, or even operate, leading to a growing demand for managed SIEM services, whether provided by the SIEM vendor or third-party partners.

SIEM solutions continue to vie for space with other security solutions, such as endpoint detection and response (EDR), security orchestration automation and response (SOAR), and security analytics solutions. All SIEM vendors support integrations with other security solutions. Many vendors also offer tightly integrated solution stacks, allowing customers to choose the solutions they need most, whether just a SIEM, a SIEM and a SOAR, or some other combination. Other vendors are incorporating limited EDR- or SOAR-like capabilities into their SIEM solutions for customers who want the extra features but are not ready to invest in multiple solutions.

With so many options, choosing a SIEM solution is challenging. You will have to consider several key factors, starting with your existing IT infrastructure. Is an on-premises SIEM the right choice for you, or do you want a cloud-based or hybrid solution? Which systems and devices will be sending data to your SIEM, and how much data will it need to collect, correlate, analyze, and store? You should also consider the relative importance of basic capabilities and advanced features, bearing in mind that the basic capabilities may be considerably easier to deploy, maintain, and operate. Will your IT and security teams be able to deploy, maintain, and operate the solution on their own, or should you look for managed services to handle those tasks?

This GigaOm Radar report details the key SIEM solutions on the market, identifies key criteria and evaluation metrics for selecting a SIEM, and identifies vendors and products that excel. It will give you an overview of the key SIEM offering and help decision-makers evaluate existing solutions and decide where to invest.

How to Read this Report

This GigaOm report is one of a series of documents that helps IT organizations assess competing solutions in the context of well-defined features and criteria. For a fuller understanding consider reviewing the following reports:

Key Criteria report: A detailed market sector analysis that assesses the impact that key product features and criteria have on top-line solution characteristics—such as scalability, performance, and TCO—that drive purchase decisions.

GigaOm Radar report: A forward-looking analysis that plots the relative value and progression of vendor solutions along multiple axes based on strategy and execution. The Radar report includes a breakdown of each vendor’s offering in the sector.

Solution Profile: An in-depth vendor analysis that builds on the framework developed in the Key Criteria and Radar reports to assess a company’s engagement within a technology sector. This analysis includes forward-looking guidance around both strategy and product.

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Key Criteria for Evaluating a Distributed Denial of Service (DDoS) Solution

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Although ransomware is making all the headlines today, it’s not the only kind of attack that can intrude between you and your customers. Distributed denial of service (DDoS) attacks, in which a target website is overwhelmed with spurious traffic, have become increasingly common.

Websites and online applications have become critical to how businesses communicate with their customers and partners. If those websites and applications are not available, there is a dollars and cents cost for businesses, both directly in business that is lost and indirectly through loss of reputation. It doesn’t matter to the users of the website whether the attacker has a political point to make, wants to hurt their victim financially, or is motivated by ego—if the website is unavailable, users will not be happy. Recent DDoS attacks have utilized thousands of compromised computers and they can involve hundreds of gigabits per second of attack bandwidth. A DDoS protection platform must inspect all of the traffic destined for the protected site and discard or absorb all of the hostile traffic while allowing legitimate traffic to reach the site.

Often the attack simply aims vast amounts of network traffic at the operating system under the application. These “volumetric” attacks usually occur at network Layer 3 or 4 and originate from compromised computers called bots. Few companies have enough internet bandwidth to mitigate this much of an attack on-premises, so DDoS protection needs to be distributed to multiple data centers around the world to be effective against these massive attacks. The sheer scale of infrastructure required means that most DDoS platforms are multi-tenant cloud services.

Other attacks target the application itself, at Layer 7, with either a barrage of legitimate requests or with requests carefully crafted to exploit faults in the site. These Layer 7 attacks look superficially like real requests and require careful analysis to separate them from legitimate traffic.

Attackers do not stand still. As DDoS protection platforms learn to protect against one attack method, attackers will find a new method to take down a website. So DDoS protection vendors don’t stand still either. Using information gathered from observing all of their protected sites, vendors are able to develop new techniques to protect their clients.

How to Read this Report

This GigaOm report is one of a series of documents that helps IT organizations assess competing solutions in the context of well-defined features and criteria. For a fuller understanding consider reviewing the following reports:

Key Criteria report: A detailed market sector analysis that assesses the impact that key product features and criteria have on top-line solution characteristics—such as scalability, performance, and TCO—that drive purchase decisions.

GigaOm Radar report: A forward-looking analysis that plots the relative value and progression of vendor solutions along multiple axes based on strategy and execution. The Radar report includes a breakdown of each vendor’s offering in the sector.

Solution Profile: An in-depth vendor analysis that builds on the framework developed in the Key Criteria and Radar reports to assess a company’s engagement within a technology sector. This analysis includes forward-looking guidance around both strategy and product.

Continue Reading

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