Spearphishing Attachment
Spearphishing attachment is a specific variant of spearphishing. Spearphishing attachment is different from other forms of spearphishing in that it employs the use of malware attached to an email. All forms of spearphishing are electronically delivered social engineering targeted at a specific individual, company, or industry. In this scenario, adversaries attach a file to the spearphishing email and usually rely upon User Execution to gain execution. There are many options for the attachment such as Microsoft Office documents, executables, PDFs, or archived files. Upon opening the attachment (and potentially clicking past protections), the adversary's payload exploits a vulnerability or directly executes on the user's system. The text of the spearphishing email usually tries to give a plausible reason why the file should be opened, and may explain how to bypass system protections in order to do so. The email may also contain instructions on how to decrypt an attachment, such as a zip file password, in order to evade email boundary defenses. Adversaries frequently manipulate file extensions and icons in order to make attached executables appear to be document files, or files exploiting one application appear to be a file for a different one.
Mitigations |
|
| Mitigation | Description |
|---|---|
| Antivirus/Antimalware |
Use signatures or heuristics to detect malicious software. |
| Spearphishing Attachment Mitigation |
Network intrusion prevention systems and systems designed to scan and remove malicious email attachments can be used to block activity. Solutions can be signature and behavior based, but adversaries may construct attachments in a way to avoid these systems. Block unknown or unused attachments by default that should not be transmitted over email as a best practice to prevent some vectors, such as .scr, .exe, .pif, .cpl, etc. Some email scanning devices can open and analyze compressed and encrypted formats, such as zip and rar that may be used to conceal malicious attachments in Obfuscated Files or Information. Because this technique involves user interaction on the endpoint, it's difficult to fully mitigate. However, there are potential mitigations. Users can be trained to identify social engineering techniques and spearphishing emails. To prevent the attachments from executing, application whitelisting can be used. Anti-virus can also automatically quarantine suspicious files. |
| Network Intrusion Prevention |
Use intrusion detection signatures to block traffic at network boundaries. |
| Restrict Web-Based Content |
Restrict use of certain websites, block downloads/attachments, block Javascript, restrict browser extensions, etc. |
| User Training |
Train users to be aware of access or manipulation attempts by an adversary to reduce the risk of successful spearphishing, social engineering, and other techniques that involve user interaction. |
Detection
Network intrusion detection systems and email gateways can be used to detect spearphishing with malicious attachments in transit. Detonation chambers may also be used to identify malicious attachments. Solutions can be signature and behavior based, but adversaries may construct attachments in a way to avoid these systems. Anti-virus can potentially detect malicious documents and attachments as they're scanned to be stored on the email server or on the user's computer. Endpoint sensing or network sensing can potentially detect malicious events once the attachment is opened (such as a Microsoft Word document or PDF reaching out to the internet or spawning Powershell.exe) for techniques such as Exploitation for Client Execution and Scripting.
Связанные риски
Каталоги
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