External Attack Surface Management (EASM)

As organizations expand, their external attack surface grows proportionally with the addition of more domains, internet-facing services, and cloud assets. Each new endpoint, be it a web portal, API, or cloud service, offers potential entry points for attackers. This expanding digital footprint increases vulnerability risks and emphasizes the need for robust cybersecurity measures to defend against potential external threats.

This blog delves into the external attack surface, its key components, strategies for organizations to manage it, the lifecycle of an EASM program, and insights from Gartner’s hype cycle on EASM.

What Is External Attack Surface?

The external attack surface of an organization encompasses the entire area of a system or organization that is susceptible to an attack from external sources. It represents the collection of all points and interfaces exposed to the outside world, where unauthorized users might attempt to gain access or extract information.

An organization’s external attack surface typically consists of:

Internet-facing Assets

Internet-facing assets are any servers, devices, or systems that are directly reachable from the public internet. They represent the digital face of an organization to the external world. Due to their exposure, they are often the first target for attackers, as exploiting vulnerabilities in these assets can provide initial foothold or access to the organization’s internal network or sensitive data.

Web servers, for instance, can be compromised to host malicious content or serve as a platform for further lateral movement inside an organization’s network. Mail servers, another pivotal asset, if breached, can be manipulated to intercept or send deceptive emails, aiding in phishing or spear-phishing campaigns. DNS servers are vital for traffic direction; a malicious actor gaining control can redirect users to fraudulent sites, a tactic commonly used for phishing or man-in-the-middle attacks. FTP and file servers, given their primary function of storing and transferring data, can be treasure troves of sensitive information. An adversary targeting these can steal, alter, or ransom the stored data.

Web Applications

Websites, online platforms, and web services/APIs that the organization offers to its customers, partners, or the general public are prime targets of adversaries. Vulnerabilities in these platforms can be exploited in various ways.

Web platforms, such as e-commerce sites and customer portals, are susceptible to various cyberattacks. Attackers can exploit SQL Injection vulnerabilities to manipulate databases, for instance, extracting customer data from an online store. Cross-Site Scripting (XSS) allows malicious actors to inject scripts into web pages, potentially hijacking user sessions on an e-commerce site. Cross-Site Request Forgery (CSRF) can deceive users into unintentionally performing actions, like initiating fund transfers on banking portals. Inadequate session management can lead to session hijacking, permitting unauthorized access, while file inclusion vulnerabilities might let attackers run harmful scripts, compromising servers. Furthermore, security misconfigurations, such as unprotected directories, can expose critical data. Given these threats, robust security practices are paramount for web applications.

Remote Access Points

Remote Access Points, encompassing tools like VPNs, RDP, and SSH, are invaluable for modern organizations, facilitating connections from virtually anywhere to the company’s internal network. Their increased use, augmented by the shift to remote work, amplifies their presence on an organization’s external attack surface. However, if inadequately safeguarded, this convenience can become a magnet for cyber adversaries.

Vulnerabilities in VPN solutions, misconfigurations, or compromised credentials of remote employees can be identified and exploited to grant unauthorized access.

Cloud Assets

Cloud assets have swiftly become cornerstones in modern organizational infrastructure, amplifying operational efficiency through their innate flexibility and scalability. However, their integration also means they significantly shape the external attack surface. While they promise convenience, they bring forth many challenges, notably misconfigurations.

For instance, an inadvertently exposed S3 bucket on AWS can turn into massive reputation and financial losses due to data breaches.

Official and Sub Domains

Official domains and subdomains play a crucial role in defining an organization’s online presence, acting as the primary interfaces for external traffic and interactions. They are significant contributors to the external attack surface of an organization, being directly accessible from the internet.

Domains often carry critical functionalities, and any misconfiguration can lead to potential security lapses. Outdated or misconfigured SSL/TLS certificates, for instance, can compromise the integrity and confidentiality of data during transmission. Additionally, legacy subdomains, which may have been created for past projects or campaigns, might not be monitored or updated regularly, making them susceptible to exploits.

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