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Update v8.19.25

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This section lists all updates associated with version 8.19.25 of the Fleet integration Prebuilt Security Detection Rules.

Rule Description Status Version

Suspicious Instance Metadata Service (IMDS) API Request

This rule identifies various tools/scripts performing network activities attempting to access the cloud service provider’s instance metadata service (IMDS) API endpoint, which can be used to retrieve sensitive instance-specific information such as instance ID, public IP address, and even temporary security credentials if roles are assumed by that instance.

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Azure Run Command Script Child Process

Identifies process start events whose parent matches Azure Virtual Machine Run Command execution patterns on Windows or Linux. On Windows, Run Command often launches PowerShell with -ExecutionPolicy Unrestricted and a script?.ps1 file; on Linux, the Azure Linux Agent (waagent) runs downloaded script.sh under "/var/lib/waagent/run-command/". Child process telemetry exposes the on-guest payload that cloud activity logs do not fully describe.

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Azure Run Command Correlated with Process Execution

Correlates successful Azure Virtual Machine Run Command operations with endpoint process execution on the same host within minutes. Adversaries abuse Run Command to run scripts remotely as SYSTEM or root while activity logs only record the control-plane action; Elastic Defend process telemetry reveals the on-guest payload.

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AWS S3 Credential File Retrieved from Bucket

Detects successful S3 GetObject calls targeting high-value credential and secret files commonly stored in S3 buckets: AWS credentials files (".aws/credentials", ".aws/config"), SSH private keys ("id_rsa", "id_ed25519", "id_ecdsa", "id_dsa"), environment files (".env"), PEM and PuTTY key files, and other private key patterns. These file types are high-yield targets for credential harvesting from S3. The rule excludes AWSService identity type to suppress S3 replication, Glacier restore, and other AWS-internal data movement that legitimately reads these files.

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Entra ID Kali365 Default User-Agent Detected

Identifies the default user agent string associated with Kali365 (also referred to as Kali365 Live), a phishing-as-a-service (PhaaS) platform that automates OAuth 2.0 device code phishing and adversary-in-the-middle (AiTM) session capture against Microsoft 365 and Microsoft Entra ID. The Kali365 Electron desktop client identifies itself with the user agent kali365-live/1.0.0 when polling for and replaying captured OAuth tokens, so its appearance in Entra ID sign-in logs, Entra ID audit logs, or the Microsoft 365 unified audit log indicates that an attacker-controlled Kali365 client is interacting with the tenant using stolen tokens. Unlike dual-use offensive tooling, Kali365 is a criminal service with no legitimate enterprise use, making this user agent a high-fidelity indicator of active account compromise.

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Entra ID Microsoft Authentication Broker Sign-In with Non-Standard User Agent

Detects Microsoft Entra ID sign-in activity where the Microsoft Authentication Broker authenticates is using a user agent that is not consistent with common browser, mobile, or Windows platform authentication clients. Adversary-in-the-middle and OAuth phishing tooling often presents scripted or relayed user agents (for example Node.js, Python, or generic HTTP libraries) while still targeting first-party resources through the broker.

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Azure VM Extension Deployment by User

Identifies the successful deployment of a high-risk Azure Virtual Machine extension by an interactive user principal. Attackers with privileged Azure RBAC roles can abuse VM extensions such as VMAccess, CustomScriptExtension, and RunCommand to execute arbitrary code, create backdoor accounts, harvest credentials, and establish persistence on Azure-hosted virtual machines without requiring direct network access to the VM.

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Entra ID Device Registration with ROADtools Default OS Build

Identifies a Microsoft Entra ID device registration where the recorded cloud device operating system build is "10.0.19041.928" and the device display name follows the default "DESKTOP-" pattern. This combination is the default device profile that ROADtools (roadtx) uses when registering a device, and it is uncommon for the OS build to match the hardcoded value across an environment of otherwise patched hosts. Adversaries register rogue devices in Entra ID to acquire a Primary Refresh Token (PRT), establish persistence, and obtain trusted, programmatic access to the tenant. Because the OS build is a tool default, this is a high-fidelity but evadable indicator; baseline approved provisioning tooling and device naming conventions before relying on it.

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Entra ID Device with ROADtools Default OS Build (Entity Analytics)

Identifies the first occurrence of a Microsoft Entra ID device, surfaced through the Entra ID Entity Analytics device inventory, whose host name follows the default "DESKTOP-" pattern and whose operating system build is 10.0.19041.928. This combination is the default device profile that ROADtools (roadtx) uses when registering a device, and the OS build typically differs from the patched OS versions of legitimate hosts in the environment. Adversaries register rogue devices in Entra ID to acquire a Primary Refresh Token (PRT), establish persistence, and obtain trusted, programmatic access to the tenant. Because the OS build is a tool default, this is a high-fidelity but evadable indicator; baseline approved device builds and naming conventions before relying on it.

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Google Workspace User Login with Unusual ASN

Detects the first time a Google Workspace user successfully signs in from a given source ASN within a 14-day historical window. Most users have a stable set of egress ASNs (home ISP, corporate VPN, mobile carrier). A new ASN for a user is a meaningful anomaly as it surfaces ISP changes and travel, but also catches AiTM phishing-kit relays whose egress ASN was never previously associated with the user.

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Google Workspace User Sign-in from Atypical Device Type

Detects the first time a Google Workspace user is observed authenticating from a device of a given type (e.g., WINDOWS, MAC, ANDROID, IOS, LINUX) within a historical window. Note that "DEVICE_REGISTER_UNREGISTER_EVENT" events do not represent one-time physical device enrollments; the Google Reports API emits a fresh "google_workspace.device.id" on each event, and the same physical device may produce multiple events per day as sessions/sync renewals occur. The rule therefore surfaces a user authenticating from a new device type, not a new physical device. This is still high-fidelity because adversaries who compromise a Workspace identity via AiTM kits or stolen OAuth refresh tokens frequently relay sessions from device types that diverge from the legitimate user’s baseline (e.g., a WINDOWS session appearing for a known macOS user, or simultaneous WINDOWS+MAC sessions within minutes), which is the canonical kit fingerprint. Because the underlying token retains access after password rotation, treat unexpected device-type divergence as a compromise indicator and revoke tokens, not just credentials.

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Google Workspace Device Registration Burst for Single User

Detects bursts of Google Workspace device registration events for the same user, where three or more distinct "google_workspace.device.id" values are emitted in a one-minute window. Although "DEVICE_REGISTER_UNREGISTER_EVENT" fires routinely on session/sync registration and is not a true physical device enrollment, legitimate user activity typically produces fewer than three distinct device IDs in a single minute. A high-cardinality burst is the fingerprint behavior of AiTM phishing-kit relays (Tycoon2FA Google variant, EvilGinx phishlets) and stolen-OAuth-token replay tooling, both of which mint a new session attestation per relay or replay attempt.

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M365 Exchange Inbox Rule with Obfuscated Name

Identifies when a Microsoft Exchange inbox rule is created or modified with a name composed only of special characters. Adversaries may use obfuscated inbox rule names to evade detection, hide malicious forwarding or deletion rules, or blend in with benign audit noise. The rule name is parsed from "o365.audit.ObjectId", which encodes the mailbox identity and rule name separated by a backslash.

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Segfault from Sensitive Process Detected

Monitors kernel logs for segfault messages from sensitive processes. A segfault, or segmentation fault, is an error that occurs when a program tries to access a memory location that it’s not allowed to access, typically leading to program termination. A segfault can be an indication of malicious behavior if it results from attempts to exploit buffer overflows, inject shared objects, or other vulnerabilities in software to execute arbitrary code or disrupt its normal operation.

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Passwordless Sudo Probing

This rule detects passwordless sudo probing activity on Linux systems. Passwordless sudo probing can be an indication of an attacker attempting to enumerate it’s allowed commands and potential privilege escalation.

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Suspicious Command Execution via Web Server

Identifies suspicious command executions via a web server, which may suggest a vulnerability and remote shell access. Attackers may exploit a vulnerability in a web application to execute commands via a web server, or place a backdoor file that can be abused to gain code execution as a mechanism for persistence.

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Unusual Child Execution via Web Server

This rule leverages the "new_terms" rule type to detect unusual child process executions originating from web server processes on Linux systems. Attackers may exploit web servers to maintain persistence on a compromised system, often resulting in atypical child process executions. As child process spawns from web server parent processes are common, the "new_terms" rule type approach helps identify deviations from normal behavior.

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Cloud Instance Metadata Credential Path HTTP Request

Detects HTTP GET requests to the link-local instance metadata service (169.254.169.254) for cloud credential or token paths on AWS, GCP, or Azure. Adversaries and vulnerable workloads use scripts, shells, or application runtimes to read IAM role credentials or OAuth tokens from the metadata API. Requires the Network Packet Capture integration with HTTP decoding on ports 80 and 443 and process enrichment enabled so "process.*" fields are present.

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Suspicious Instance Metadata Service (IMDS) API Command Line Execution

This rule identifies various tools/scripts performing command line execution attempting to access the cloud service provider’s instance metadata service (IMDS) API endpoint, which can be used to retrieve sensitive instance-specific information such as instance ID, public IP address, and even temporary security credentials if roles are assumed by that instance.

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AWS SSM Session Manager Child Process Execution

Identifies process start events where the parent process is the AWS Systems Manager (SSM) Session Manager worker. Session Manager provides interactive shell access to EC2 instances and hybrid nodes without bastion hosts or open inbound ports. Adversaries abuse it for remote execution and lateral movement using legitimate AWS credentials and IAM permissions. This rule surfaces endpoint execution occurring under that worker for visibility and hunting. Expect noise from authorized administrative sessions.

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M365 or Entra ID Identity Sign-in from a Suspicious Source

This rule correlate Entra-ID or Microsoft 365 mail successful sign-in events with network security alerts by source address. Adversaries may trigger some network security alerts such as reputation or other anomalies before accessing cloud resources.

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AWS AssumeRoleWithWebIdentity from Kubernetes SA and External ASN

Detects successful AssumeRoleWithWebIdentity where the caller identity is a Kubernetes service account and the source autonomous system organization is present but not Amazon.com, Inc. EKS workloads that obtain IAM credentials via IAM Roles for Service Accounts (IRSA) normally reach STS from AWS-managed or AWS-associated networks; the same identity from a clearly external ASN can indicate a stolen or misused projected service-account token being exchanged for IAM credentials off-cluster.

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Entra ID OAuth User Impersonation to Microsoft Graph

Identifies potential session hijacking or token replay in Microsoft Entra ID. This rule detects cases where a user signs in and subsequently accesses Microsoft Graph from a different IP address using the same session ID. This may indicate a successful OAuth phishing attack, session hijacking, or token replay attack, where an adversary has stolen a session cookie or refresh/access token and is impersonating the user from an alternate host or location.

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Google Workspace Drive Data Transfer or Takeout Export Initiated

Detects when Google Workspace administrators initiate bulk movement or export of user Drive data. This includes admin data transfer requests that reassign a user’s Drive files to another account, and Customer Takeout export jobs that package organizational data for download or off-platform transfer. Adversaries with administrative access may abuse these mechanisms to stage or exfiltrate sensitive files.

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Forwarded Google Workspace Security Alert

Identifies the occurrence of a security alert from the Google Workspace alerts center. Google Workspace’s security alert center provides an overview of actionable alerts that may be affecting an organization’s domain. An alert is a warning of a potential security issue that Google has detected.

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External User Added to Google Workspace Group

Detects an external Google Workspace user account being added to an existing group. Adversaries may add external user accounts as a means to intercept shared files or emails with that specific group.

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Google Workspace Suspended User Account Renewed

Detects when a previously suspended user’s account is renewed in Google Workspace. An adversary may renew a suspended user account to maintain access to the Google Workspace organization with a valid account.

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Google Workspace User Organizational Unit Changed

Users in Google Workspace are typically assigned a specific organizational unit that grants them permissions to certain services and roles that are inherited from this organizational unit. Adversaries may compromise a valid account and change which organizational account the user belongs to which then could allow them to inherit permissions to applications and resources inaccessible prior to.

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Kubernetes Admission Webhook Created or Modified

Detects creation, modification, or deletion of Kubernetes MutatingWebhookConfigurations or ValidatingWebhookConfigurations by non-system identities. Admission webhooks intercept every API request matching their rules before persistence, giving an attacker powerful capabilities: injecting malicious sidecars into every new pod via a mutating webhook, blocking security tooling deployments via a validating webhook, or silently exfiltrating pod specifications to an external server. Webhook manipulation is a stealthy persistence and defense evasion technique because the webhook configuration itself looks benign in kubectl output while actively modifying or intercepting all matching Kubernetes API traffic.

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M365 Exchange Inbox Forwarding Rule Created

Identifies when a new Inbox forwarding rule is created in Microsoft 365. Inbox rules process messages in the Inbox based on conditions and take actions. In this case, the rules will forward the emails to a defined address. Attackers can abuse Inbox Rules to intercept and exfiltrate email data without making organization-wide configuration changes or having the corresponding privileges.

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M365 SharePoint Site Sharing Policy Weakened

Identifies when a SharePoint or OneDrive site sharing policy is changed to weaken security controls. The SharingPolicyChanged event fires for many routine policy modifications, but this rule targets specific high-risk transitions where sharing restrictions are relaxed. This includes enabling guest sharing, enabling anonymous link sharing, making a site public, or enabling guest user access. Adversaries who compromise administrative accounts may weaken sharing policies to exfiltrate data to external accounts or create persistent external access paths.

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Kubernetes and Cloud Credential Path Access via Process Arguments

Flags Linux process executions whose arguments reference high-value Kubernetes service-account material, kubeconfig or node PKI paths, or common cloud files, when invoked via typical file-reading utilities or from ephemeral directories. Useful for spotting in-cluster and hybrid credential theft early.

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Attempt to Clear Kernel Ring Buffer

Monitors for the deletion of the kernel ring buffer events through dmesg. Attackers may clear kernel ring buffer events to evade detection after installing a Linux kernel module (LKM). This activity is commonly observed by intrusions that leverage kernel-level rootkits to maintain persistence on a compromised host.

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Kubernetes Static Pod Manifest File Access

Detects Linux process executions where shells, editors, interpreters, or file/stream utilities reference /etc/kubernetes/manifests in process arguments. That directory holds static pod manifests read by the kubelet; interaction via editors, downloaders, kubectl, redirection helpers (tee, dd), or scripting runtimes may indicate staging or tampering with manifests for persistence or privileged workload placement. Pairs with file-telemetry rules that flag direct manifest creation on container workloads.

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Deprecated - Unusual Process Spawned from Web Server Parent

This rule detects unusual processes spawned from a web server parent process by identifying low frequency counts of process spawning activity. Unusual process spawning activity may indicate an attacker attempting to establish persistence, execute malicious commands, or establish command and control channels on the host system. ESQL rules have limited fields available in its alert documents. Make sure to review the original documents to aid in the investigation of this alert.

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Deprecated - Unusual Command Execution from Web Server Parent

This rule detects potential command execution from a web server parent process on a Linux host. Adversaries may attempt to execute commands from a web server parent process to blend in with normal web server activity and evade detection. This behavior is commonly observed in web shell attacks where adversaries exploit web server vulnerabilities to execute arbitrary commands on the host. The detection rule identifies unusual command execution from web server parent processes, which may indicate a compromised host or an ongoing attack. ESQL rules have limited fields available in its alert documents. Make sure to review the original documents to aid in the investigation of this alert.

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Deprecated - Uncommon Destination Port Connection by Web Server

This rule identifies unusual destination port network activity originating from a web server process. The rule is designed to detect potential web shell activity or unauthorized communication from a web server process to external systems.

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Suspicious Child Execution via Web Server

Identifies suspicious child processes executed via a web server, which may suggest a vulnerability and remote shell access. Attackers may exploit a vulnerability in a web application to execute commands via a web server, or place a backdoor file that can be abused to gain code execution as a mechanism for persistence.

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Unusual Command Execution via Web Server

This rule leverages the "new_terms" rule type to detect unusual command executions originating from web server processes on Linux systems. Attackers may exploit web servers to maintain persistence on a compromised system, often resulting in atypical command executions. As command execution from web server parent processes is common, the "new_terms" rule type approach helps to identify deviations from normal behavior.

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Potential Privilege Escalation via unshare and UID Change

Identifies potentially suspicious use of unshare to create a user namespace context followed by a UID change event indicating a transition to root. Adversaries may use unshare-based primitives as part of local privilege escalation chains. This rule is intentionally generic and can surface multiple local privesc patterns beyond a single CVE.

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Suspicious AWS S3 Connection via Script Interpreter

Detects when a script interpreter (osascript, Node.js, Python) with minimal arguments makes an outbound connection to AWS S3 or CloudFront domains. Threat actors have used S3 buckets for both command and control and data exfiltration. Script interpreters connecting to cloud storage should be investigated for potential malicious activity.

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Dumping Account Hashes via Built-In Commands

Identifies the execution of macOS built-in commands used to dump user account hashes. Adversaries may attempt to dump credentials to obtain account login information in the form of a hash. These hashes can be cracked or leveraged for lateral movement.

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Suspicious Web Browser Sensitive File Access

Identifies the access or file open of web browser sensitive files by an untrusted/unsigned process or osascript. Adversaries may acquire credentials from web browsers by reading files specific to the target browser.

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Potential Privacy Control Bypass via TCCDB Modification

Identifies the use of sqlite3 to directly modify the Transparency, Consent, and Control (TCC) SQLite database. This may indicate an attempt to bypass macOS privacy controls, including access to sensitive resources like the system camera, microphone, address book, and calendar.

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Accepted Default Telnet Port Connection

This rule detects network events that may indicate the use of Telnet traffic. Telnet is commonly used by system administrators to remotely control older or embedded systems using the command line shell. It should almost never be directly exposed to the Internet, as it is frequently targeted and exploited by threat actors as an initial access or backdoor vector. As a plain-text protocol, it may also expose usernames and passwords to anyone capable of observing the traffic.

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Abnormally Large DNS Response

Specially crafted DNS requests can manipulate a known overflow vulnerability in some Windows DNS servers, resulting in Remote Code Execution (RCE) or a Denial of Service (DoS) from crashing the service.

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Rare Connection to WebDAV Target

Identifies rare connection attempts to a Web Distributed Authoring and Versioning (WebDAV) resource. Attackers may inject WebDAV paths in files or features opened by a victim user to leak their NTLM credentials via forced authentication.

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