Detections
Explore public detection logic contributed by the community across SIEM and rule languages.
545 detections
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Detects potential tampering with Windows Event Logs or audit services by correlating manual service stops or log clearing events (EventIDs 1100, 1102, 104, 7036, 7040) with a sudden, significant decrease in total event volume on the same host. The rule accounts for planned maintenance and legitimate event log service restarts to reduce noise.
Detects signs of email bombing by monitoring for critical thresholds in mail server queue size, transfer latency, or a significant spike in SMTP connection attempts targeting individual mailboxes. This activity often aims to disrupt email service availability, bury critical alerts, or facilitate social engineering attacks.
Detects a high volume of subscription or account confirmation emails directed at a single recipient within a one-hour window. This behavior, often referred to as 'email bombing,' can be used to disrupt user productivity, overwhelm inbox capacity, or serve as a distraction technique to hide other malicious activities, such as spearphishing or account takeover notifications.
This rule detects potential command and control (C2) communication related to the GhostContainer malware. It inspects HTTP POST requests directed at Microsoft Outlook Web Access (OWA) paths containing a suspicious 'x-owa-urlpostdata' header. The presence of this specific header, followed by a base64-encoded string of significant length, indicates an attempt to deliver C2 commands or exfiltrate data through OWA infrastructure.
Detects the GhostContainer .NET-based backdoor assembly deployed on compromised Microsoft Exchange servers, requiring multiple corroborating unique indicators (C2 header, proxy class name, virtual path parameters) alongside .NET/PE structure to reduce false positives
Detects unauthenticated HTTP POST requests to the PaperCut web management interface that attempt to modify server configuration settings. This behavior is consistent with exploitation attempts targeting vulnerabilities like CVE-2026-81578, which may allow for unauthorized pre-authentication remote code execution.
This rule detects high-frequency account and email address enumeration attempts. It monitors syslog data for SMTP commands such as VRFY, EXPN, or RCPT TO, and analyzes Microsoft Entra ID (SigninLogs) for authentication failures specifically associated with error code 50034 (user not found). Both behaviors are indicative of an adversary attempting to validate user identities within an environment, often as a precursor to targeted phishing or brute-force attacks.
This rule monitors for Exchange administration operations where mailbox permissions ('FullAccess', 'SendAs', or 'SendOnBehalf') are granted to a user. It specifically flags instances where the account performing the action is neither the owner of the target mailbox nor the grantee, identifying suspicious, potentially unauthorized delegation patterns.
Detects a significant surge of bulk or spam mail quarantine events for a single mailbox within a 15-minute window. This behavior often indicates a mail-bombing attack intended to overwhelm the user or as a distraction technique (smokescreen) to hide concurrent malicious activities such as exfiltration, lateral movement, or ransomware staging in the M365 tenant.
Detects instances where a high-value security or transaction-related notification email is received concurrently with a burst of non-essential bulk or subscription-based emails. This pattern is indicative of an email-bombing (inbox flooding) attack, often used to bury critical alerts and mask malicious activity such as unauthorized account access or fraudulent financial transactions.
This rule detects high-frequency account and email address enumeration attempts. It monitors syslog data for SMTP commands such as VRFY, EXPN, or RCPT TO, and analyzes Microsoft Entra ID (SigninLogs) for authentication failures specifically associated with error code 50034 (user not found). Both behaviors are indicative of an adversary attempting to validate user identities within an environment, often as a precursor to targeted phishing or brute-force attacks.
Detects the execution of cmd.exe as a child process of the IIS worker process (w3wp.exe) when the worker process is associated with an Exchange application pool. This pattern is indicative of a webshell exploiting an ASPX component to execute arbitrary commands on an Exchange Server.
Detects an Exchange server initiating outbound SMB (port 445) connections to non-private (external) IP addresses. This behavior is highly characteristic of PetitPotam (MS-EFSR) coercion, where an attacker forces the server to authenticate to an external, attacker-controlled UNC path to capture NTLM authentication credentials or relay them to other network resources.
This rule detects the creation or modification of suspicious files (extensions associated with web shells or modules, such as .aspx, .ashx, .asmx, .dll, or .config) within common Microsoft IIS and Exchange web directories. It correlates these file events with process activity initiated by common web server or management processes (e.g., w3wp.exe, powershell.exe) and filters out trusted files (Microsoft-signed), known administrative update activity, and files with a broader footprint in the environment to identify potentially malicious, low-prevalence artifacts.
Detects the use of curl.exe or curl to communicate with the malicious domain 'i.apee.my.id', initiated by a VS Code integrated terminal process. This behavior is indicative of malicious VS Code extensions exfiltrating data via a hidden terminal session.
Detects Microsoft Entra audit events where a user is added to either the Global Administrator or Cloud Device Administrator built-in roles, which are high-privilege administrative roles.
Detects anomalous mailbox access via the MailItemsAccessed operation, specifically identifying the unique ClientAppId and API pairing associated with the Storm-2755 (Payroll Pirates) adversary campaign. This activity indicates unauthorized access to email content, typically targeting high-value personnel such as payroll, finance, and HR staff through Adversary-in-the-Middle (AiTM) techniques.
This rule detects potentially malicious activity where an attacker, having performed a password reset or MFA change on a compromised account, attempts to hide their tracks by rapidly deleting security-related notification emails (e.g., password reset alerts) shortly after they arrive in the user's mailbox. It correlates Exchange mailbox operations with audit log account security changes to filter out routine noise.
Detects malicious script execution triggered by the CVE-2026-42897 XSS vulnerability in Outlook Web Access (OWA). The detection rule monitors AMSI script detection events for patterns associated with the OWAReaper exploit chain, which utilizes an 'onload=eval(atob())' loader to reconstruct a base64-encoded payload embedded in social-icon image tags within a browser session.
This rule identifies suspicious email messages that contain isolated blocks of text preceded by at least two whitespace characters (including newlines, carriage returns, or tabs). This pattern is often used by threat actors to obfuscate content, attempt to bypass email gateway filters, or hide malicious strings from security scanners by breaking up content flow.
Detects Microsoft Exchange EWS/OWA HTTP requests containing URL-encoded file scheme indicators (e.g., 'file%3a', '%66%69%6c%65'). This activity is associated with attempts to bypass security filters via scheme smuggling, potentially to facilitate Server-Side Request Forgery (SSRF) exploitation leading to unauthorized local file access.
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