[Zero-day] Understanding zero-day attacks

 

Intro 

We start an ordinary day. We drink coffee while checking our emails, and install the latest software updates. Suddenly, the computer starts acting strangely. It slows down, files won't open, and the system seems paralyzed. This might be a sign of an impending zero-day malware attack.

A 'Zero-Day' attack refers to an attack that exploits vulnerabilities not yet identified by security experts. Predicting and defending against these attacks is challenging, making them extremely dangerous.

In this article, we will explore what a zero-day attack is, how it occurs, and strategies to shield ourselves from these threats.

1. Definition

Zero-day attacks stand out as one of the most disruptive cybersecurity threats, posing a significant challenge even to security experts. The term 'Zero-Day' refers to an attack that occurs before a security vulnerability is publicly disclosed - essentially, on 'day zero'. Attackers discover and exploit these vulnerabilities while they remain unknown to software developers and security professionals. The essence of a zero-day attack lies in its unpredictability and the difficulty of defense. Attackers use these vulnerabilities to deploy malware. Although there are various types of attacks such as ransomware, backdoor installations, network interference, and DDoS attacks, malware utilizing zero-day attacks remain among the most active.

For an in-depth definition of Zero-Day Attack, please refer to the ITU-T X.1236 established by International Telecommunication Union (ITU).

6.1. General characteristics, section 6.1.1. Zero-day malware attacks

Targeted email attacks mainly involve the use of new malware that can be challenging to detect using general pattern recognition. In particular, by exploiting a zero-day vulnerability, malicious developers can create malware that takes advantage of a vulnerability before a corresponding security program is developed and deployed. This implies that malware exploiting vulnerabilities can propagate extensively before organizations can effectively mitigate the threat.

2. Risk

Unpredictablility

Zero-day attacks are characterized by their occurrence in a state where vulnerabilities have not been disclosed, making it challenging to prevent or prepare for them in advance.

The lack of prior knowledge about these vulnerabilities adds to the difficulty in predicting when and how an attack will occur.

This distinctive feature is elaborated in the definition of [7.1.1. Zero-day malware] as per ITU-T X.1236.

As zero-day malware is not registered in large-scale databases, identifying the unknown malware used by attackers becomes challenging for security systems. 

Severe Consequences

Zero-Day attacks have the potential to result in the theft of personal information, financial data theft, and system paralysis. These attacks can inflict substantial losses, particularly for businesses.

The general types of damage caused by these attacks are detailed in Section 7.1.1 of the ITU-T X.1236 on zero-day malware.

Exploiting the vulnerability of zero-day, attackers insert an attachment or a clickable link containing unknown malware that goes undetected by the security system. Subsequently, they send an email designed to induce users into clicking where they shouldn’t.

Zero-day malwares may gain access to the memory of a victim’s computer system, enabling them to damage or delete files and programs.

Delayed Response

Given that zero-day attacks exploit vulnerabilities before they are known, it takes time for security companies to develop and distribute patches. Consequently, during this period, the attack continues to cause damage, amplifying the overall impact.

Difficulty in Recovery

Recovering the system to its original state is challenging after a zero-day attack. Since this attack method is not registered in cybersecurity-related big data, fining a solution becomes a time-consuming process. This delay in response naturally complicates the recovery or restoration efforts following the attack.

3. Types of Attackers

Zero-day malware attacks are carried out by attackers with a variety of motivations. Gaining an understanding of their motives, targets, and the techniques they use is crucial for the development of effective cybersecurity strategies.

Hacktivists

Often conduct attacks to convey social or political messages, drawing public attention to their causes. Their objectives may range from the disclosure of information to exposing the illegal activities of governments or large corporations.

Cybercriminals

Exploit zero-day vulnerabilities to steal personal financial information, sensitive corporate data, or other valuable information for illicit gains.

Corporate Spies

Engage in high-level, targeted attacks to uncover secrets of competing companies or organizations. Their goal is to gain competitive advantages or acquire important market information.

Cyber Warfare

Conducted by nations or political actors, aims to attack or monitor the critical cyber infrastructure of an enemy country. This form of warfare is used for information gathering, infrastructure disruption, or exercising political influence.

4. Attack Examples 

Attack on Iran's Nuclear Facilities

One of the most notable instances of a zero-day vulnerability exploitation is the 'Stuxnet attack on Iran's nuclear facilities'.

Stuxnet, discovered in 2010, was a highly sophisticated malware specifically designed to target Iran's Natanz nuclear facility. Its primary purpose was to disrupt Iran's uranium enrichment program. Stuxnet infiltrated the industrial control systems managing Iran's centrifuges, resulting in physical damage. The malware exploited several zero-day vulnerabilities in the Windows operating system and notably spread through USB drives.

What set Stuxnet apart was its unique objective. Instead of focusing solely on data corruption or system paralysis, Stuxnet aimed to manipulate specific industrial control systems, leading to tangible and physical destruction. This case demonstrated how cyber actions have tangible and physical consequences, showcasing the evolving landscape of cyber threats and their impact on the physical realm.

Attack on Microsoft Word Users

In early April 2017, a significant Zero-Day attack targeted Microsoft Word users in Australia. This incident was part of a large-scale email campaign delivering the Trojan Dridex. Victims fell prey to a banking Trojan horse when they downloaded and opened a Word document containing numerous macros from a malicious email. The Dridex botnet was then installed upon opening these documents. Notably, the malware only executed if the infected Word file was opened with the 'Enable Editing' feature activated, and the spread continued as many users granted editing permissions to the downloaded documents. Microsoft promptly addressed the security issue by releasing a related patch on April 11, 2017.

5. How to Prevent

​With the rapid growth of the internet, the IT industry is also expanding. Despite significant progress in security technologies, we are still not free from Zero-Day attacks. While it's challenging to completely prevent such attacks, the risk can be minimized through the following methods:

Regular Updates

Ensure that systems and software are kept up-to-date and promptly apply security patches from manufacturers to minimize vulnerabilities.

Network Firewalls

Implement network firewalls to block malicious traffic and prevent external intrusions.

Intranet Security

Reinforce security within internal networks to prevent internal attacks and be prepared for Zero-Day attacks.

Security Applications

Enhance the security for vulnerable applications, and if necessary, introduce security solutions to improve the detection and blocking of malware.

User Education

Provide cybersecurity training to employees and users, educating them to avoid malicious links and encouraging the prompt reporting of suspicious activities.

Malicious File Detection

Utilize antivirus and malware detection solutions to identify and block malicious files.

Network Monitoring

Continuously monitor network activity 24/7, detect unusual signs, and respond swiftly.

6. Solutions

The response to zero-day attacks must be multifaceted. The most crucial elements in preventing and responding to these attacks are appropriate preventive measures and a rapid response strategy.

First, both organizations and individuals should recognize cybersecurity as an essential element, not optional one. Regular security updates, strong password policies, and data backups are basic yet essential measures.

In the event of detecting a zero-day attack, it's crucial to immediately disconnect the device from all network connections without turning it off. This prevents further damage and aids in preserving data for forensic investigation.

Reset all system and administrator account passwords, and if necessary, disable Wi-Fi and deactivate critical network connections.

If there is no decryption solution for the infected system, consider attempting system restoration or reinstalling the OS, which is the most reliable way to cleanse and recover the infected system. Installing and updating antivirus software, along with regular scans, are essential to remove any residual infections and prevent future attacks.

7. References

<Title: Revised baseline text for X.1221 (Xsr-ctea): Security requirements and countermeasures for targeted email attacks (for consent)>

ITU-T Recommendation database

 

ITU-T Recommendation database

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