SecurityBrief Australia logo
Australia's leading source of cybersecurity and cyber-attack news
Story image

Beware of these six L7 DDoS attacks

By Contributor
Fri 7 Aug 2020
FYI, this story is more than a year old

Article by Radware product marketing manager Eyal Arazi.

The nature of DDoS attacks is changing. Not too long ago, large-scale network-layer floods were attackers’ tools of choice, using malformed TCP and UDP packets to take down targets with high volumes of network traffic.

Over time, however, defences have adapted to protect against such volumetric attacks, to the point where even most ISPs and public cloud vendors provide basic protection against network-layer floods.

But instead of sitting idle, attackers are constantly devising new ways to challenge DDoS protections. As more services are migrating online, DDoS attacks are increasingly shifting away from the network layer, and into the application layer.

Application-layer (L7) DDoS attacks pose a unique challenge for DDoS defences, as they require insight into application behaviour, and it is difficult to tell whether a request is legitimate or malicious simply by looking at the network-layer traffic.

As more web traffic is encrypted by SSL and HTTPS, DDoS defences are frequently unable to look at the contents of the packet itself. As a result, many DDoS defences are unable to tell the difference between a legitimate spike in customer traffic (for example, during a flash crowd or a holiday peak) and an actual attack.

Here are six types of application-layer (L7) DDoS attacks to watch out for:
 
HTTP/S floods

These work by directing large numbers of HTTP requests to a web page in order to overload target servers with requests. This attack is similar to other types of network-level flooding attacks, except that it operates at the application layer, using high volumes of HTTP/S GET or HTTP/S POST requests.

In fact, as the vast majority of internet traffic nowadays is encrypted, most HTTP flood attacks today are HTTPS floods. These encrypted floods are much more potent because of the high amount of server resources required to handle them, and they also add a layer of complexity to mitigating such attacks, since DDoS defences usually cannot inspect the contents of the HTTPS requests without fully decrypting all traffic.
 

Negotiation attack - AKA 'SSL garbage flood'

An SSL negotiation attack targets specifically the SSL handshake mechanism of web applications in order to overload server resources. 

The SSL/TLS handshake mechanism is a highly asymmetric process, which requires up to 15 times more computing resources from the incoming server than from the client making the request. Attackers can launch devastating DDoS attacks using only a small number of requests.

SSL negotiation attacks work by sending large numbers of ‘garbage’ SSL/TLS connection initiation requests to overwhelm the server’s resources and ability to accept new connections. 

Although HTTPS floods take advantage of this mechanism, there are other variations such as encrypted SYN floods or SSL renegotiation attacks (which continuously create, drop, then re-create SSL handshakes).
 

Low-and-slow attack

Like flood attacks, low-and-slow attacks aim to take down target servers by overwhelming server resources. However, unlike flood attacks, low-and-slow attacks do so not by sending high volume bursts of traffic. 

Instead, they take the opposite approach by sending a small number of connections but keeping them open as long as possible until they exhaust the target server’s resources.

This approach allows low-and-slow attacks to ‘fly under the radar’ of traditional DDoS defences based on volume thresholds, since they do not cause large spikes in traffic which can be ‘capped off’ by rate limits.

There are numerous variations of this approach, usually named after the hacking tools which use them. One common attack variation is Slowloris, which keeps HTTP requests open by continually sending partial HTTP headers, but never completing the request.

Another well-known variation is RUDY (‘R U Dead Yet?’) which creates HTTP POST connections with the server, but avoids sending any POST data for as long as possible (and then sending the data at a very slow rate) – drawing out the connection and limiting the server’s ability to accept new connections.
 

HTTP/S bomb – AKA ‘Large payload attack’

An ‘HTTP bomb’ uses the HTTP POST method to send large, complex POST requests (usually scripted as an XML data structure), which the target server will attempt to parse. 

However, due to the size and complexity of the POST request (i.e., the ‘bomb’), the server will end up using high amounts of computing resources, ultimately depleting them and bringing the server down.

This can be a particularly difficult attack to mitigate, since it can use a high number of server resources with a limited number of connections.
 

Large file download – AKA ‘Outbound pipe saturation attack’

Unlike most DDoS attacks, this attack vector does not target the server’s incoming traffic pipe, but rather aims at saturating the outbound traffic connection.

Many web-based services allow downloads of large files such as software updates, OS images, databases, application data, etc. Even modern web pages can be very large if they include heavy graphics and other objects.

Large file download attacks aim at exhausting the server’s ability to communicate externally by saturating the outbound connection with large amounts of outbound data.

This can be a very effective type of asymmetric attack, since the request can be only a few bytes, whereas the reply can be gigabytes in size. Moreover, outbound pipe saturation attacks can be very difficult to detect and mitigate since most DDoS defences look only at incoming traffic, not outgoing traffic.

Although not specifically designated as such, many types of web application attacks also bear the hallmarks of a DDoS flood. This is because like DDoS floods, application brute force attacks frequently come in at a high rate and generate high-volumes of application-layer error messages, which need to be processed and handled by the server.

Examples of such brute force attempts include server scanning, password cracking, credential stuffing, and more. The challenge with dealing with such attacks is that without processing the request first, it is usually very difficult to know which request is legitimate and which is not.
 

Denial of inventory

This application-layer attack is not a DDoS attack per se, but it achieves the same objectives by denying an organisation’s ability to serve its customers. Denial of inventory attacks use automated bots to go into organisations’ applications and initiate purchase requests, without actually completing the purchase.

As a result, the inventory relating to the purchase request – such as airline tickets, event tickets, stock inventory, etc. – is temporarily locked, and unavailable to customers trying to purchase the same inventory.

Although this attack does not target the traffic pipe or server resources, it achieves the same result of denying service from legitimate customers. 

This is a particularly difficult form of attack to mitigate, since it is difficult to discern an actual paying customer from a bot.

Related stories
Top stories
Story image
Tech job moves
Tech job moves - Adatree, Brother, Databricks, Nutanix & Rubrik
We round up all job appointments from May 20-26, 2022, in one place to keep you updated with the latest from across the tech industries.
Story image
Cybersecurity
4/10 Australian SMEs fallen victim to cyber-attacks since pandemic
Almost four out of teb SMEs in Australia have fallen victim to cyber-attacks since the pandemic began, according to a new study.
Story image
Transport
Third-party automotive apps bear significant privacy risks
Mobile applications for connected cars provide various features to make life easier for motorists, but they can also be a source of risk.
Story image
Malware
Fortinet introduces self-learning AI in latest offering
Fortinet is introducing self-learning AI capabilities in its new network detection and response offering, FortiNDR.
Story image
BYOD / Bring Your Own Device
How zero trust can lead the battle against ransomware
SecOps teams champion a zero trust strategy to support the fight against the escalating risk of cybercrime and help monitor threat actors across a network.
Story image
Ponemon Institute
Email revealed to be riskiest channel for data loss
More than half (60%) of organisations experienced data loss or exfiltration caused by an employee mistake on email in the last 12 months.
Story image
Managed service provider
Barracuda MSP Day 2022 highlights MSP opportunities
Barracuda Networks has released a report showing global services-related MSP revenue is set to increase by more than a third in 2022 compared to 2021.
Story image
Microsoft
Elevation of Privilege the top 2021 Microsoft vulnerability
BeyondTrust has released its 2022 Microsoft Vulnerabilities Report, finding that Elevation of Privilege is the top vulnerability category for the second consecutive year.
Story image
Malware
New vulnerabilities found in Nuspire’s Q1 2022 Threat Report
“Threat actors are quickly adjusting their tactics and these exploits tend to get industry attention, but the threat posed by older and attacks still persists."
Story image
Data Protection
Information management capabilities to meet privacy requirements
Organisations with customers or operations across more than one country face a spate of new and proposed privacy and data protection laws.
Story image
Silver Peak
The path to an adaptive, modern network
Managing and securing the network looks different than it did just two years ago—especially given that most of these networks are made up of multi-generations of infrastructure stitched together over time.
Story image
Cybersecurity
Asia Pacific plagued by sophisticated bad bots - report
The three most common bot attacks were account takeover, content or price scraping, and scalping to obtain limited-availability items.
Story image
Remote Working
Successful digital transformation in the hybrid work era is about embracing shifting goalposts
As organisations embraced remote working, many discovered they lacked the infrastructure needed to support history’s first global load test of remote work capabilities.
Story image
Ransomware
APAC ranks third-highest region targeted by ransomware
Asia Pacific has ranked the third-highest region globally to be targeted by ransomware, according to cybersecurity firm Group-IB.
Story image
Cybersecurity
Cybersecurity prompts upgrade for 1.3 billion electricity meters
ABI Research finds Advanced Metering Infrastructure (AMI) and cybersecurity concerns are prompting the upgrade of 1.3 billion electricity meters by 2027.
Story image
ChildFund
ChildFund launches new campaign to protect children online
ChildFund says WEB Safe & Wise aims to protect children from sexual exploitation and abuse online while also empowering them to become digitally savvy. 
Story image
Artificial Intelligence
Gartner reveals top three tech trends for banks this year
Gartner says generative artificial intelligence, autonomic systems and privacy-enhancing computation are gaining traction in banking and investment services.
Story image
Cloud Security
Aqua Security createa unified scanner for cloud native security
“By integrating more cloud native scanning targets into Trivy, such as Kubernetes, we are simplifying cloud native security."
Story image
Cybersecurity
More than 40% of banks worried about cloud security - report
Publicis Sapient's new report finds security and the lack of cloud skills and internal understanding of business benefits are big obstacles for banks moving to the cloud.
Story image
Migration
Let’s clear the cloud visibility haze with app awareness
Increasingly, organisations are heading for the cloud, initiating new born-in-the-cloud architectures and migrating existing applications via ‘lift and shift’ or refactoring.
Story image
Ransomware
APAC organisations fail to disclose ransomware breaches
85% of organisations in APAC were breached by ransomware at least once in the past five years, but only 28% publicly disclosed the incident.
Story image
Cyber attacks
Devastating cyber attacks expected to hit energy sector
Energy executives anticipate life, property, and environment-compromising cyber attacks on the sector within the next two years.
Story image
Kubernetes
Sysdig unveils new Kubernetes troubleshooting and cloud innovations
Sysdig has introduced two new innovations that look to help bolster cloud services and simplify Kubernetes troubleshooting.
Story image
Customer experience
Gartner recognises Okta for abilities in Access Management
Okta has announced it has been recognised as a Customers' Choice for the fourth time in a row in the Gartner Peer Insights "Voice of the Customer" report.
Story image
Cybersecurity
What every CISO must answer to enable a best-in-class security operations program
It has been widely reported recently that South Australian government employees have been the victims of a cyberattack.
Story image
Malware
'Alarming' rise in ransomware threats - Verizon report
As criminals look to leverage increasingly sophisticated forms of malware, it is ransomware that continues to prove particularly successful.
Story image
Microsoft
Global cybersecurity insurance market worth $11.5b this year
Future Market Insights finds the cybersecurity insurance market is expected to reach USD$11.5 billion in 2022, growing to $61.2 billion in 10 years.
Story image
New Relic
New Relic launches vulnerability management platform
New Relic has introduced New Relic Vulnerability Management to help organisations find and address security risks faster and with greater precision.
Story image
Employment
Tech job moves - Forcepoint, Malwarebytes, SolarWinds & VMware
We round up all job appointments from May 13-20, 2022, in one place to keep you updated with the latest from across the tech industries.
Story image
Remote Working
Australia’s remote workers face connectivity and security issues
SOTI's new report finds better video conferencing technology and improved security measures are top concerns for remote workers in Australia.
Story image
Ransomware
Employees on the frontline of cyber defense - report
In the first quarter of 2022, employees found themselves more than ever at the frontline of cyber defense, according to a new report from Kroll. 
Story image
VPN
The most common online scams in Australia
No one is safe from online scammers, and many of these scammers have capitalised on the pandemic, using this confusing time to attack more people than ever.
Story image
Amazon Web Services / AWS
RedShield leverages AWS to scale cybersecurity services
"Working with AWS gives RedShield the ability to mitigate significant application layer DDoS attacks, helping leaders adopt best practices and security architectures."
Story image
Training
Trojan cyber attacks hitting SMBs harder than ever - Kaspersky
In 2022 the number of Trojan-PSW detections increased by almost a quarter compared to the same period in 2021 to reach 4,003,323.
Story image
Phishing
WhatsApp and QR codes the next scam threat - report
KnowBe4 has warned it expects to see an increase in QR Codes and the WhatsApp chat platform being used for phishing and other scams. 
Story image
Surveillance
i-PRO releases smallest AI-based surveillance camera on the market
The new i-PRO mini network camera is now available, with a pocket-sized form factor and full AI analytics functionality.
Story image
Cybersecurity
Noname Security partners with Netpoleon to target API issues
Specialist API security firm Noname Security has appointed Netpoleon as its distributor in Australia and New Zealand.
Story image
Training
Infosec unveils role-guided cybersecurity training roadmaps
Infosec Skills Roles maps hands-on training and certifications to the 12 most in-demand cybersecurity roles to maximise training efficiency.
Story image
Data Protection
Barracuda launches new capabilities for API Protection
"Every business needs this type of critical protection against API vulnerabilities and automated bot attacks," Barracuda says.
Story image
Cybersecurity
Comcast to use ThreatQuotient for cybersecurity operations
Comcast, the parent company of NBC Universal and SKY Group, has chosen ThreatQ Platform and ThreatQ Investigations to meet their cybersecurity needs.
Story image
Phishing
MailGuard warns of new scam targeting Telstra customers
Telstra customers in Australia are being warned of a new scam involving "Unsuccessful Payment" messages.
Story image
Cybersecurity
Accenture - a collective security approach a driving factor for cyber resilience
With the approaching Davos World Economic Forum upon us, it is even more imperative to discuss the impact of cybersecurity on business operations leading into the future.
Story image
Check Point
Check Point and CCTV expert join forces to boost protection
The partnership will involve Check Point Quantum IoT Protect Nano Agent being embedded in Provision-ISR’s CCTV cameras for on-device runtime protection.
Story image
Identity and Access Management
The post-pandemic workforce requires secure IAM capabilities
HID Global discusses what identity and access management means for organisations in today's convoluted digital world.