Detections
Explore public detection logic contributed by the community across SIEM and rule languages.
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Detects phishing attempts related to 'Operation DoppelBrand' campaign using common email service providers (ESPs) to spoof legitimate-looking emails with fraud-themed subjects, such as invoices or payment requests, associated with the Brickstorm malware.
Detects SMTP MAIL FROM/Reply-To headers, DNS queries, or TLS SNI matches for known Business Email Compromise (BEC) lookalike domains (e.g., service-nowinc.com, domainlify.net) used for phishing or spoofing organizational identities.
Detects SMTP MAIL FROM/Reply-To headers, DNS queries, or TLS SNI matches for known Business Email Compromise (BEC) lookalike domains (e.g., service-nowinc.com, domainlify.net) used for phishing or spoofing organizational identities.
Detects phishing attempts related to 'Operation DoppelBrand' campaign using common email service providers (ESPs) to spoof legitimate-looking emails with fraud-themed subjects, such as invoices or payment requests, associated with the Brickstorm malware.
Detects phishing attempts related to 'Operation DoppelBrand' campaign using common email service providers (ESPs) to spoof legitimate-looking emails with fraud-themed subjects, such as invoices or payment requests, associated with the Brickstorm malware.
Detects SMTP MAIL FROM/Reply-To headers, DNS queries, or TLS SNI matches for known Business Email Compromise (BEC) lookalike domains (e.g., service-nowinc.com, domainlify.net) used for phishing or spoofing organizational identities.
Detects SMTP traffic containing XLSX file attachments, specifically looking for base64 encoded content that matches the criteria for CVE-2025-60727. This rule monitors network traffic for the delivery of potential malicious Office documents.
Detects SMTP traffic containing XLSX file attachments, specifically looking for base64 encoded content that matches the criteria for CVE-2025-60727. This rule monitors network traffic for the delivery of potential malicious Office documents.
This rule detects the outbound transmission of email attachments via SMTP (ports 25 and 587) that contain archived file formats (zip, 7z, tar.gz, tgz). Attackers often compress collected data into archives to facilitate exfiltration and minimize the time required for data transfer.
This rule detects the outbound transmission of email attachments via SMTP (ports 25 and 587) that contain archived file formats (zip, 7z, tar.gz, tgz). Attackers often compress collected data into archives to facilitate exfiltration and minimize the time required for data transfer.
This rule detects the presence of a Right-to-Left Override (RLO) character sequence in the content of an email sent over SMTP. The RLO character (U+202E, represented as E2 80 AE in UTF-8) is often used in phishing or malware campaigns to visually reverse the order of characters in a filename, making an executable file appear to be a benign file type (e.g., 'document.txt.exe' could appear as 'document.exe.txt'). The rule specifically looks for this byte sequence in traffic destined for port 25 (SMTP) and flags it as trojan activity.
This rule detects a high volume of inbound emails to port 25 (SMTP), indicating a potential email bombing attack. It triggers an alert if more than 100 emails are received from a single source IP address within a 60-second window.
This rule detects email attachments that use a double extension, specifically looking for files that appear to be common document or image types (doc, pdf, jpg) but have a hidden executable extension (exe, bat, vbs). This technique is often used by attackers to trick users into opening malicious files.
This rule detects emails sent to the internal network (SMTP port 25) that attempt to impersonate an internal IT department. It specifically looks for the 'From:' header, the phrase 'IT Department' (case-insensitive), and the word 'password' (case-insensitive) within the email content. This combination suggests a social engineering attempt, likely phishing, to trick recipients into revealing credentials.
This rule detects SMTP traffic where an email is failing SPF (Sender Policy Framework) authentication. Specifically, it looks for the 'Received-SPF: fail' header in emails sent to port 25 ($HOME_NET). This indicates that the sending server is not authorized to send email on behalf of the domain specified in the email's 'MAIL FROM' address, which is a strong indicator of a phishing attempt or spoofed email.
This rule detects executable attachments (e.g., .exe, .bat, .cmd, .scr, .pif, .com) being delivered via SMTP email. It specifically looks for these file extensions within the 'filename' attribute of email attachments.
This rule detects emails sent over SMTP where the 'From:' and 'Reply-To:' headers are present, indicating a potential attempt to spoof the sender's display name while using a different domain. It triggers an alert if 10 such emails are observed from the same source within 60 seconds, suggesting a bulk email or phishing attempt.
This rule detects email spoofing attempts where the 'From' address domain does not match the 'Return-Path' address domain. It specifically looks for SMTP traffic on port 25, ensuring the flow is established and to the server. The rule uses PCRE to extract the domain from the 'From' header and then checks if the 'Return-Path' header contains a different domain.
This rule detects phishing emails sent over SMTP that contain macro-enabled documents (Word or Excel files) as attachments. It specifically looks for base64 encoded content, the 'filename=' attribute, and uses a PCRE to identify common macro-enabled file extensions like .doc, .docx, .xls, .xlsm, and .xlsb within the filename.
This rule detects phishing emails that deliver survey or form lures by identifying specific content patterns within SMTP traffic. It looks for emails with 'Content-Type: application/' and 'filename=' headers, specifically targeting attachments with file extensions like .doc, .docx, .pdf, or .xlsx, which are commonly used in social engineering attacks to deliver malicious documents or forms.
This rule detects internal SMTP traffic that contains both 'Content-Type: application/' and 'filename=' in the email body. This combination is often indicative of an attachment being sent, and in the context of 'Lateral Phishing' (T1534), it suggests an attempt to send malicious attachments internally. The rule is set to trigger an alert if 5 such events occur from the same source IP within 300 seconds, indicating a potential automated or high-volume internal phishing attempt.
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