Malicious emails remain some of the most common and destructive computer security threats businesses face today. Research shows that email as a threat vector represents 96% of cyberattacks carried out across various industries. Cybercriminals use email-based attacks to steal login credentials, lure individuals into clicking malicious links, and deliver malware. This article will discuss why opening an attachment delivered via email is not always safe, and how to avoid being the victim of an attack.
Warning Signs of A Malicious Attachment
Malware is a type of software designed by cybercriminals to specifically cause harm to a network or device. Threat actors may use an attached document, PDF, or image to convince you to open the attachment, secretly launching the malware. Office routines have had to change due to the ongoing pandemic, creating gaps in regular reminders on online security protocols. An important part of protecting your organization’s network is to avoid dangerous email attachments. Malware is designed to steal data, sabotage, and extort money. This can be done by one of several different techniques such as phishing or ransomware. Some ways to spot a malicious attachment include:
- Exe files – An executable file (.exe) has encoded instructions that tell a computer system set a function in motion. Exe files are often legitimate Windows applications; however, they can also be used to distribute viruses or other malware.
- Compressed files – Compressed files can be used to send large volumes of information and bundle multiple files or folders after shrinking them to a size that can be delivered. These files can also be used to disguise malware. File extensions you might be familiar with are .zip; .rar; .sitx; .gz).
- Microsoft Office Documents – The new functionality of macro and scripting capabilities are very similar to executable programs in that they tell systems to run processes. Attackers can use this to embed their own scripting and malware.
Threat actors will often pose as a known source and use social engineering tactics to convince you they are who they seem to be. These strategies are constantly evolving and developing new ways to manipulate targets, priming them for an attack. The tactics will vary, but three approaches commonly employed by cybercriminals include:
- Malicious attachments – Cyber criminals will often send emails with malicious attachments that can install ransomware, keyloggers, and other malware on the victim’s device when opened.
- Malicious links – These are often located in the body of the email and account for a high number of data breaches, malicious URLs are more common than email attachments in attacks, often using HTTPS links.
- Transaction enticements – Cyber criminals use this social engineering approach to convince victims to compromise sensitive information or perform a financial transaction without requiring links or attachments.
Email Attachment Threats
Malicious attachments account for a large portion of malware deliveries, so it is crucial to be aware of the most common methods of email attachment threats. The top four email attachment threats that businesses are likely to face are:
- Ransomware – Ransomware is a threat that works by encrypting a victim’s data and demands that you pay a fee to restore the stolen data. Ransomware is delivered via email attachment and launched when the attachment is opened.
- Phishing – Phishing attacks use social engineering to manipulate victims into sharing sensitive information that can be sold for malicious purposes. The message is designed to deceive the recipient by making the victim believe that the email was sent by a trusted individual or business. This convinces the victim into opening infected attachments without thinking about what might be included in the attachment.
- Keyloggers – User credentials are typically always stolen in the event of a severe data breach. Cybercriminals will often use keyloggers to steal IDs and passwords to pull this off, which can be hidden within an email attachment and launched once opened, or when the target opens a malicious link. Afterward, the keylogger can record keys pressed on the user’s keyboard to capture passwords and other account details.
- Zero-day exploits – Zero-day attacks target zero-day vulnerabilities, or flaws or security weaknesses that the software developer is unaware of. These vulnerabilities are exploited before the vendor can fix them. Often delivered by email, this threat is sometimes stored in attachments, allowing hackers unauthorized access to private information.
The Bottom Line
Interacting with an unsafe email attachment by opening it, forwarding it, or replying to it can have severe consequences for you, your device, and even your organization. The first step in protecting yourself is being more aware and vigilant, and by taking a few security measures, it is possible for you to mitigate many risks online. These are tips that everyone in your organization should learn, particularly during this time of operational disruption when cybercriminals are most active. Ultimately, stick to the golden rule: if in doubt, don’t proceed until you’re confident that it’s safe to do so.