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Learn how firewall rules secure your network from cyber threats. Explore types, best practices, and management strategies to optimize your firewall security. Firewall rules & requirements (inbound vs. outbound) ---- ------- Schedule a Demo Select a size ----- Get the latest insights from the experts Use these six best practices to simplify compliance and risk mitigation with the AlgoSec platform White paper Learn how AlgoSec can help you pass PCI-DSS Audits and ensure continuous compliance Solution overview See how this customer improved compliance readiness and risk management with AlgoSec Case study Choose a better way to manage your network

As you may have heard already, the National Security Agency (NSA) and the Federal Bureau of Investigation (FBI) released a joint... Cloud Security Drovorub’s Ability to Conceal C2 Traffic And Its Implications For Docker Containers Rony Moshkovich 2 min read Rony Moshkovich Short bio about author here Lorem ipsum dolor sit amet consectetur. Vitae donec tincidunt elementum quam laoreet duis sit enim. Duis mattis velit sit leo diam. Tags Share this article 8/15/20 Published As you may have heard already, the National Security Agency (NSA) and the Federal Bureau of Investigation (FBI) released a joint Cybersecurity Advisory about previously undisclosed Russian malware called Drovorub. According to the report, the malware is designed for Linux systems as part of its cyber espionage operations. Drovorub is a Linux malware toolset that consists of an implant coupled with a kernel module rootkit, a file transfer and port forwarding tool, and a Command and Control (C2) server. The name Drovorub originates from the Russian language. It is a complex word that consists of 2 roots (not the full words): “drov” and “rub” . The “o” in between is used to join both roots together. The root “drov” forms a noun “drova” , which translates to “firewood” , or “wood” . The root “rub” /ˈruːb/ forms a verb “rubit” , which translates to “to fell” , or “to chop” . Hence, the original meaning of this word is indeed a “woodcutter” . What the report omits, however, is that apart from the classic interpretation, there is also slang. In the Russian computer slang, the word “drova” is widely used to denote “drivers” . The word “rubit” also has other meanings in Russian. It may mean to kill, to disable, to switch off. In the Russian slang, “rubit” also means to understand something very well, to be professional in a specific field. It resonates with the English word “sharp” – to be able to cut through the problem. Hence, we have 3 possible interpretations of ‘ Drovorub ‘: someone who chops wood – “дроворуб” someone who disables other kernel-mode drivers – “тот, кто отрубает / рубит драйвера” someone who understands kernel-mode drivers very well – “тот, кто (хорошо) рубит в драйверах” Given that Drovorub does not disable other drivers, the last interpretation could be the intended one. In that case, “Drovorub” could be a code name of the project or even someone’s nickname. Let’s put aside the intricacies of the Russian translations and get a closer look into the report. DISCLAIMER Before we dive into some of the Drovorub analysis aspects, we need to make clear that neither FBI nor NSA has shared any hashes or any samples of Drovorub. Without the samples, it’s impossible to conduct a full reverse engineering analysis of the malware. Netfilter Hiding According to the report, the Drovorub-kernel module registers a Netfilter hook. A network packet filter with a Netfilter hook ( NF_INET_LOCAL_IN and NF_INET_LOCAL_OUT ) is a common malware technique. It allows a backdoor to watch passively for certain magic packets or series of packets, to extract C2 traffic. What is interesting though, is that the driver also hooks the kernel’s nf_register_hook() function. The hook handler will register the original Netfilter hook, then un-register it, then re-register the kernel’s own Netfilter hook. According to the nf_register_hook() function in the Netfilter’s source , if two hooks have the same protocol family (e.g., PF_INET ), and the same hook identifier (e.g., NF_IP_INPUT ), the hook execution sequence is determined by priority. The hook list enumerator breaks at the position of an existing hook with a priority number elem->priority higher than the new hook’s priority number reg->priority : int nf_register_hook ( struct nf_hook_ops * reg) { struct nf_hook_ops * elem; int err; err = mutex_lock_interruptible( & nf_hook_mutex); if (err < 0 ) return err; list_for_each_entry(elem, & nf_hooks[reg -> pf][reg -> hooknum], list) { if (reg -> priority < elem -> priority) break ; } list_add_rcu( & reg -> list, elem -> list.prev); mutex_unlock( & nf_hook_mutex); ... return 0 ; } In that case, the new hook is inserted into the list, so that the higher-priority hook’s PREVIOUS link would point into the newly inserted hook. What happens if the new hook’s priority is also the same, such as NF_IP_PRI_FIRST – the maximum hook priority? In that case, the break condition will not be met, the list iterator list_for_each_entry will slide past the existing hook, and the new hook will be inserted after it as if the new hook’s priority was higher. By re-inserting its Netfilter hook in the hook handler of the nf_register_hook() function, the driver makes sure the Drovorub’s Netfilter hook will beat any other registered hook at the same hook number and with the same (maximum) priority. If the intercepted TCP packet does not belong to the hidden TCP connection, or if it’s destined to or originates from another process, hidden by Drovorub’s kernel-mode driver, the hook will return 5 ( NF_STOP ). Doing so will prevent other hooks from being called to process the same packet. Security Implications For Docker Containers Given that Drovorub toolset targets Linux and contains a port forwarding tool to route network traffic to other hosts on the compromised network, it would not be entirely unreasonable to assume that this toolset was detected in a client’s cloud infrastructure. According to Gartner’s prediction , in just two years, more than 75% of global organizations will be running cloud-native containerized applications in production, up from less than 30% today. Would the Drovorub toolset survive, if the client’s cloud infrastructure was running containerized applications? Would that facilitate the attack or would it disrupt it? Would it make the breach stealthier? To answer these questions, we have tested a different malicious toolset, CloudSnooper, reported earlier this year by Sophos. Just like Drovorub, CloudSnooper’s kernel-mode driver also relies on a Netfilter hook ( NF_INET_LOCAL_IN and NF_INET_LOCAL_OUT ) to extract C2 traffic from the intercepted TCP packets. As seen in the FBI/NSA report, the Volatility framework was used to carve the Drovorub kernel module out of the host, running CentOS. In our little lab experiment, let’s also use CentOS host. To build a new Docker container image, let’s construct the following Dockerfile: FROM scratch ADD centos-7.4.1708-docker.tar.xz / ADD rootkit.ko / CMD [“/bin/bash”] The new image, built from scratch, will have the CentOS 7.4 installed. The kernel-mode rootkit will be added to its root directory. Let’s build an image from our Dockerfile, and call it ‘test’: [root@localhost 1]# docker build . -t test Sending build context to Docker daemon 43.6MB Step 1/4 : FROM scratch —> Step 2/4 : ADD centos-7.4.1708-docker.tar.xz / —> 0c3c322f2e28 Step 3/4 : ADD rootkit.ko / —> 5aaa26212769 Step 4/4 : CMD [“/bin/bash”] —> Running in 8e34940342a2 Removing intermediate container 8e34940342a2 —> 575e3875cdab Successfully built 575e3875cdab Successfully tagged test:latest Next, let’s execute our image interactively (with pseudo-TTY and STDIN ): docker run -it test The executed image will be waiting for our commands: [root@8921e4c7d45e /]# Next, let’s try to load the malicious kernel module: [root@8921e4c7d45e /]# insmod rootkit.ko The output of this command is: insmod: ERROR: could not insert module rootkit.ko: Operation not permitted The reason why it failed is that by default, Docker containers are ‘unprivileged’. Loading a kernel module from a docker container requires a special privilege that allows it doing so. Let’s repeat our experiment. This time, let’s execute our image either in a fully privileged mode or by enabling only one capability – a capability to load and unload kernel modules ( SYS_MODULE ). docker run -it –privileged test or docker run -it –cap-add SYS_MODULE test Let’s load our driver again: [root@547451b8bf87 /]# insmod rootkit.ko This time, the command is executed silently. Running lsmod command allows us to enlist the driver and to prove it was loaded just fine. A little magic here is to quit the docker container and then delete its image: docker rmi -f test Next, let’s execute lsmod again, only this time on the host. The output produced by lsmod will confirm the rootkit module is loaded on the host even after the container image is fully unloaded from memory and deleted! Let’s see what ports are open on the host: [root@localhost 1]# netstat -tulpn Active Internet connections (only servers) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 1044/sshd With the SSH server running on port 22 , let’s send a C2 ‘ping’ command to the rootkit over port 22 : [root@localhost 1]# python client.py 127.0.0.1 22 8080 rrootkit-negotiation: hello The ‘hello’ response from the rootkit proves it’s fully operational. The Netfilter hook detects a command concealed in a TCP packet transferred over port 22 , even though the host runs SSH server on port 22 . How was it possible that a rootkit loaded from a docker container ended up loaded on the host? The answer is simple: a docker container is not a virtual machine. Despite the namespace and ‘control groups’ isolation, it still relies on the same kernel as the host. Therefore, a kernel-mode rootkit loaded from inside a Docker container instantly compromises the host, thus allowing the attackers to compromise other containers that reside on the same host. It is true that by default, a Docker container is ‘unprivileged’ and hence, may not load kernel-mode drivers. However, if a host is compromised, or if a trojanized container image detects the presence of the SYS_MODULE capability (as required by many legitimate Docker containers), loading a kernel-mode rootkit on a host from inside a container becomes a trivial task. Detecting the SYS_MODULE capability ( cap_sys_module ) from inside the container: [root@80402f9c2e4c /]# capsh –print Current: = cap_chown, … cap_sys_module, … Conclusion This post is drawing a parallel between the recently reported Drovorub rootkit and CloudSnooper, a rootkit reported earlier this year. Allegedly built by different teams, both of these Linux rootkits have one mechanism in common: a Netfilter hook ( NF_INET_LOCAL_IN and NF_INET_LOCAL_OUT ) and a toolset that enables tunneling of the traffic to other hosts within the same compromised cloud infrastructure. We are still hunting for the hashes and samples of Drovorub. Unfortunately, the YARA rules published by FBI/NSA cause False Positives. For example, the “Rule to detect Drovorub-server, Drovorub-agent, and Drovorub-client binaries based on unique strings and strings indicating statically linked libraries” enlists the following strings: “Poco” “Json” “OpenSSL” “clientid” “—–BEGIN” “—–END” “tunnel” The string “Poco” comes from the POCO C++ Libraries that are used for over 15 years. It is w-a-a-a-a-y too generic, even in combination with other generic strings. As a result, all these strings, along with the ELF header and a file size between 1MB and 10MB, produce a false hit on legitimate ARM libraries, such as a library used for GPS navigation on Android devices: f058ebb581f22882290b27725df94bb302b89504 56c36bfd4bbb1e3084e8e87657f02dbc4ba87755 Nevertheless, based on the information available today, our interest is naturally drawn to the security implications of these Linux rootkits for the Docker containers. Regardless of what security mechanisms may have been compromised, Docker containers contribute an additional attack surface, another opportunity for the attackers to compromise the hosts and other containers within the same organization. The scenario outlined in this post is purely hypothetical. There is no evidence that supports that Drovorub may have affected any containers. However, an increase in volume and sophistication of attacks against Linux-based cloud-native production environments, coupled with the increased proliferation of containers, suggests that such a scenario may, in fact, be plausible. Schedule a demo Related Articles Q1 at AlgoSec: What innovations and milestones defined our start to 2026? AlgoSec Reviews Mar 19, 2023 · 2 min read 2025 in review: What innovations and milestones defined AlgoSec’s transformative year in 2025? AlgoSec Reviews Mar 19, 2023 · 2 min read Navigating Compliance in the Cloud AlgoSec Cloud Mar 19, 2023 · 2 min read Speak to one of our experts Speak to one of our experts Work email* First name* Last name* Company* country* Select country... Short answer* By submitting this form, I accept AlgoSec's privacy policy Schedule a call

Sunburst Backdoor A deeper look into The SolarWinds’ Supply Chain Malware Download PDF Schedule time with one of our experts Schedule time with one of our experts Work email* First name* Last name* Company* country* Select country... Short answer* By submitting this form, I accept AlgoSec's privacy policy Continue

The power of double-layered protection across your cloud estate Download PDF Schedule time with one of our experts Schedule time with one of our experts Work email* First name* Last name* Company* country* Select country... Short answer* By submitting this form, I accept AlgoSec's privacy policy Continue

THE FIREWALL AUDIT CHECKLIST Six Best Practices for Simplifying Firewall Compliance and Risk Mitigation Download PDF Schedule time with one of our experts Schedule time with one of our experts Work email* First name* Last name* Company* country* Select country... Short answer* By submitting this form, I accept AlgoSec's privacy policy Continue

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In the fast-paced world of technology, where innovation drives success, organizations find themselves in a perpetual race to enhance... Application Connectivity Management Navigating the complex landscape of dynamic app security with AlgoSec AppViz Malcom Sargla 2 min read Malcom Sargla Short bio about author here Lorem ipsum dolor sit amet consectetur. Vitae donec tincidunt elementum quam laoreet duis sit enim. Duis mattis velit sit leo diam. Tags Share this article 8/10/23 Published In the fast-paced world of technology, where innovation drives success, organizations find themselves in a perpetual race to enhance their applications, captivate customers, and stay ahead of the competition. But as your organization launches its latest flagship CRM solution after months of meticulous planning, have you considered what happens beyond Day 0 or Day 1 of the rollout? Picture this: your meticulously diagrammed application architecture is in place, firewalls are fortified, and cloud policies are strategically aligned. The application tiers are defined, the flows are crystal clear, and security guardrails are firmly established to safeguard your prized asset. The stage is set for success – until the application inevitably evolves, communicates, and grows. This dynamic nature of applications presents a new challenge: ensuring their security, compliance, and optimal performance while navigating a complex web of relationships. Do you know who your Apps are hanging out with? Enter AlgoSec AppViz – the game-changing solution that unveil the hidden intricacies of your application ecosystem, ensuring a secure and accelerated application delivery process. In a world where agility, insights, and outcomes reign supreme, AppViz offers a revolutionary approach to handling application security. The urgent need for application agility In a landscape driven by customer demands, competitive advantages, and revenue growth, organizations can’t afford to rest on their laurels. However, as applications become increasingly complex, managing them becomes a monumental task: – Infrastructure Complexity: Juggling on-premises, cloud, and multi-vendor solutions is a daunting endeavor. – Conflicting Demands: Balancing the needs of development, operations, and management often leads to a tug-of-war. – Rising Customer Expectations: Meeting stringent time-to-market and feature release demands becomes a challenge. – Resource Constraints : A scarcity of application, networking, and security resources hampers progress. – Instant Global Impact: A single misstep in application delivery or performance can be broadcasted worldwide in seconds. – Unseen Threats: Zero-day vulnerabilities and ever-evolving threat landscapes keep organizations on edge. The high stakes of ignoring dynamic application management Failure to adopt a holistic and dynamic approach to application delivery and security management can result in dire consequences for your business: – Delayed Time-to-Market: Lags in application deployment can translate to missed opportunities and revenue loss. – Revenue Erosion: Unsatisfied customers and delayed releases can dent your bottom line. – Operational Inefficiencies: Productivity takes a hit as resources are wasted on inefficient processes. – Wasted Investments: Ill-informed decisions lead to unnecessary spending. – Customer Dissatisfaction: Poor application experiences erode customer trust and loyalty. – Brand Erosion: Negative publicity from application failures tarnishes your brand image. – Regulatory Woes: Non-compliance and governance violations invite legal repercussions. The AlgoSec AppViz advantage So, how does AppViz address these challenges and fortify your application ecosystem? Let’s take a closer look at its groundbreaking features: – Dynamic Application Learning: Seamlessly integrates with leading security solutions to provide real-time insights into application paths and relationships. – Real-time Health Monitoring: Instantly detects and alerts you to unhealthy application relationships. – Intelligent Policy Management: Streamlines security policy control, ensuring compliance and minimizing risk. – Automated Provisioning: Safely provisions applications with verified business requirements, eliminating uncertainty. – Micro-Segmentation Mastery: Enables precise micro-segmentation, enhancing security without disrupting functionality. – Vulnerability Visibility: Identifies and helps remediate vulnerabilities within your business-critical applications. In a world where application agility is paramount, AlgoSec AppViz emerges as the bridge between innovation and security. With its robust features and intelligent insights, AppViz empowers organizations to confidently navigate the dynamic landscape of application security, achieving business outcomes that set them apart in a fiercely competitive environment. Request a demo and embrace the future of application agility – embrace AlgoSec AppViz. Secure, accelerate, and elevate your application delivery today. Schedule a demo Related Articles Q1 at AlgoSec: What innovations and milestones defined our start to 2026? AlgoSec Reviews Mar 19, 2023 · 2 min read 2025 in review: What innovations and milestones defined AlgoSec’s transformative year in 2025? AlgoSec Reviews Mar 19, 2023 · 2 min read Navigating Compliance in the Cloud AlgoSec Cloud Mar 19, 2023 · 2 min read Speak to one of our experts Speak to one of our experts Work email* First name* Last name* Company* country* Select country... Short answer* By submitting this form, I accept AlgoSec's privacy policy Schedule a call

Micro-segmentation: From Strategy to Execution Download PDF Schedule time with one of our experts Schedule time with one of our experts Work email* First name* Last name* Company* country* Select country... Short answer* By submitting this form, I accept AlgoSec's privacy policy Continue

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AlgoSec Security Management Solution for Cisco ACI and Cisco Nexus Dashboard Download PDF Schedule time with one of our experts Schedule time with one of our experts Work email* First name* Last name* Company* country* Select country... Short answer* By submitting this form, I accept AlgoSec's privacy policy Continue

Last week our CTO, Professor Avishai Wool, presented a technical webinar on the do’s and don’ts for managing external connectivity to and... Auditing and Compliance 4 tips to manage your external network connections Joanne Godfrey 2 min read Joanne Godfrey Short bio about author here Lorem ipsum dolor sit amet consectetur. Vitae donec tincidunt elementum quam laoreet duis sit enim. Duis mattis velit sit leo diam. Tags Share this article 8/10/15 Published Last week our CTO, Professor Avishai Wool, presented a technical webinar on the do’s and don’ts for managing external connectivity to and from your network . We kicked off our webinar by polling the audience (186 people) on how many external permanent connections into their enterprise network they have. 40% have less than 50 external connections 31% have 50-250 external connections 24% have more than 250 external connections 5% wish they knew how many external connections they have! Clearly this is a very relevant issue for many enterprises, and one which can have a profound effect on security. The webinar covered a wide range of best practices for managing the external connectivity lifecycle and I highly recommend that you view the full presentation. But in the meantime, here are a few key issues that you should be mindful of when considering how to manage external connectivity to and from your network: Network Segmentation While there has to be an element of trust when you let an external partner into your network, you must do all you can to protect your organization from attacks through these connections. These include placing your servers in a demilitarized zone (DMZ), segregating them by firewalls, restricting traffic in both directions from the DMZ as well as using additional controls such as web application firewalls, data leak prevention and intrusion detection. Regulatory Compliance Bear in mind that if the data being accessed over the external connection is regulated, both your systems and the related peer’s systems are now subject t. So if the network connection touches credit card data, both sides of the connection are in scope, and outsourcing the processing and management of regulated data to a partner does not let you off the hook. Maintenance Sometimes you will have to make changes to your external connections, either due to planned maintenance work by your IT team or the peer’s team, or as a result of unplanned outages. Dealing with changes that affect external connections is more complicated than internal maintenance, as it will probably require coordinating with people outside your organisation and tweaking existing workflows, while adhering to any contractual or SLA obligations. As part of this process, remember that you’ll need to ensure that your information systems allow your IT teams to recognize external connections and provide access to the relevant technical information in the contract, while supporting the amended workflows. Contracts In most cases there is a contract that governs all aspects of the external connection – including technical and business issues. The technical points will include issues such as IP addresses and ports, technical contact points, SLAs, testing procedures and the physical location of servers. It’s important, therefore, that this contract is adhered to whenever dealing with technical issues related to external connections. These are just a few tips and issues to be aware of. To watch the webinar from Professor Wool in full, check out the recording here . Schedule a demo Related Articles Q1 at AlgoSec: What innovations and milestones defined our start to 2026? AlgoSec Reviews Mar 19, 2023 · 2 min read 2025 in review: What innovations and milestones defined AlgoSec’s transformative year in 2025? AlgoSec Reviews Mar 19, 2023 · 2 min read Navigating Compliance in the Cloud AlgoSec Cloud Mar 19, 2023 · 2 min read Speak to one of our experts Speak to one of our experts Work email* First name* Last name* Company* country* Select country... Short answer* By submitting this form, I accept AlgoSec's privacy policy Schedule a call

AlgoSec Horizon Platform Solution brief Download PDF Schedule time with one of our experts Schedule time with one of our experts Work email* First name* Last name* Company* country* Select country... Short answer* By submitting this form, I accept AlgoSec's privacy policy Continue