The importance of patch management after serious Linux vulnerabilities 0 1032

  • The open-source Linux operating system is used by most of the servers on the internet as well as in smartphones, with an ever-growing desktop user base as well.
  • The bug known as Dirty Cow (CVE-2016-5195) – named as such since it exploits a mechanism called “copy-on-write” and falls within the class of vulnerabilities known as privilege escalation. This would allow an attacker to effectively take control of the system.
  • Patch management should be a core consideration for all IT systems, whether they are servers or workstations, and of course regardless of the operating systems used.
Serious Linux vulnerabilities

In recent news there have been a number of serious vulnerabilities found in various Linux systems. Whilst OS vulnerabilities are a common occurrence, it’s the nature of these that have garnered so much interest.

The open-source Linux operating system is used by most of the servers on the internet as well as in smartphones, with an ever-growing desktop user base as well.

Open-source software is typically considered to increase the security of an operating system, since anyone can read, re-use and suggest modifications to the source code – part of the idea being that many people involved would increase the chances of someone finding and hopefully fixing any bugs.

With that in mind let’s turn our sights on the bug known as Dirty Cow (CVE-2016-5195) found in October – named as such since it exploits a mechanism called “copy-on-write” and falls within the class of vulnerabilities known as privilege escalation. This would allow an attacker to effectively take control of the system.

What makes this particular vulnerability so concerning however isn’t the fact that it’s a privilege escalation bug, but rather that it was introduced into the kernel around nine years ago. Exploits already taking advantage of Dirty Cow were also found after the discovery of the bug by Phil Oester. This means that a reliable means of exploitation is readily available, and due to its age, it will be applicable to millions of systems.

Whilst Red Hat, Debian and Ubuntu have already released patches, millions of other devices are still vulnerable – worse still is the fact that between embedded versions of the operating and older Android devices, there are difficulties in applying the updates, or they may not receive any at all, leaving them vulnerable.

Next, let’s have a look at a more recent vulnerability which was found in Cryptsetup (CVE-2016-4484), which is used to set up encrypted partitions on Linux using LUKS (Linux Unified Key Setup). It allows an attacker to obtain a root initramfs shell on affected systems. At this point, depending on the system in question, it could be used for a number of exploitation strategies according to the researchers whom discovered the bug, namely:

  • Privilege escalation: if the boot partition is not encrypted:
    • It can be used to store an executable file with the bit “SetUID” enabled. Which can later be used to escalate privileges by a local user.
    • If the boot is not secured, then it would be possible to replace the kernel and the initrd image.
  • Information disclosure: It is possible to access all the disks. Although the system partition is encrypted it can be copied to an external device, where it can be later be brute forced. Obviously, it is possible to access to non-encrypted information in other devices.
  • Denial of service: The attacker can delete the information on all the disks, causing downtime of the system in question.

Whilst many believe the severity and/or likely impact of this vulnerability has been exaggerated considering you need physical or remote console access (which many cloud platforms provide these days), what makes it so interesting is just how it is exploited.

All you need to do is repeatedly hit the Enter key at the LUKS password prompt until a shell appears (approximately 70 seconds later) – the vulnerability is as a result of incorrect handling of password retries once the user exceeds the maximum number (by default 3).

The researchers also made several notes regarding physical access and explained why this and similar vulnerabilities remain of concern. It’s generally accepted that once an attacker has physical access to a computer, it’s pwned. However, they highlighted that with the use of technology today, there are many levels of what can be referred to as physical access, namely:

  • Access to components within a computer – where an attacker can remove/replace/insert anything including disks, RAM etc. like your own computer
  • Access to all interfaces – where an attacker can plug in any devices including USB, Ethernet, Firewire etc. such as computers used in public facilities like libraries and internet cafes.
  • Access to front interfaces – usually USB and the keyboard, such as systems used to print photos.
  • Access to a limited keyboard or other interface – like a smart doorbell, alarm, fridge, ATM etc.

Their point is that the risks are not limited to traditional computer systems, and that the growing trends around IoT devices will increase the potential reach of similar attacks – look no further than our last article on DDoS attacks since IoT devices like printers, IP cameras and routers have been used for some of the largest DDoS attacks ever recorded.

This brings us back around to the fact that now, more than ever, it’s of critical importance that you keep an eye on your systems and ensure any vulnerabilities are patched accordingly, and more importantly – in a timeous manner. Patch management should be a core consideration for all IT systems, whether they are servers or workstations, and of course regardless of the operating systems used.

To this end ESET formed another Technology Alliance with software vendor Flexera, whom recently acquired the well-known security vendor, Secunia. Through this partnership, ESET now also offers Corporate Software Inspector, one of the most popular and established patch management solutions on the market. Their 2016 review indicated that the number of vulnerabilities detected in 2015 was 16081, which were “discovered in 2484 applications from 263 vendors” and shows a worrying “39% increase over the course of the five-year trend and a 2% increase from 2014 to 2015.”

Keep an eye out for coming news, material and demos regarding Corporate Software Inspector, or contact us.

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Ransomware Protection Crucial to Enterprise 0 281

Ransomware

Ransomware is by far the biggest threat among Enterprises.  So what is Ransomware? It is a malicious code that blocks or encrypts the contents of a device and demands a ransom to restore access to the data.

According to research done by ESET,  Companies named ransomware their number one concern.

In response to customer needs and concerns, ESET integrated Ransomware Shield into its security solutions. ESET has long been providing its customers with very good behavior-based malware detection and also with Host-based Intrusion Prevention System (HIPS) that allows users to set custom rules for the protection against ransomware. However, should something slip past the 11 other security layers, Ransomware Shield will be automatically activated.

While ransomware infection often starts with clicking a suspicious link or a fictitious invoice, ESET found that email remains the most common distribution method.

To combat these scenarios, enter ESET Dynamic Threat Defense (EDTD). EDTD provides another layer of security for ESET products like Mail Security and Endpoint products. It utilizes a cloud-based sandboxing technology and multiple machine learning models to detect new, never before seen type of threats. In result, attachments that were classified as malicious are stripped off the email and the recipient gets information about the detection.

To learn more about how ESET can protect your business, and to book a FREE in house Cybersecurity Training Session for your employees, please sign up below.

Free Training

Interview: Addressing the Six Biggest Cybersecurity Challenges for Enterprise 0 199

cybersecurity challenges enterprise
Ken Kimani, Channel Manager of ESET East Africa, introduces the 6 biggest cybersecurity challenges for enterprises

Enterprises are under constant attack from cybersecurity threats resulting in the loss of millions in revenue annually. Factors such as ransomware, targeted attacks, insufficient network visibility, various operating systems in an organization, bad security behaviour among office staff, lack of skilled cybersecurity workforce and the level of tolerance among staff are the major causes of cyber-attacks in the country.

To mitigate these issues, ESET East Africa offers free training, suitable for all skill levels to help educate enterprises on the importance of cybersecurity.

Subscribe to our newsletter to find out more about this training, our enterprise offering and to follow our series on the 6 Biggest Cybersecurity Challenges for Enterprises.