Update v0.14.1

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This section lists all updates associated with version 0.14.1 of the Fleet integration Prebuilt Security Detection Rules.

Rule Description Status Version

AWS Security Group Configuration Change Detection

Identifies a change to an AWS Security Group Configuration. A security group is like a virtul firewall and modifying configurations may allow unauthorized access. Threat actors may abuse this to establish persistence, exfiltrate data, or pivot in a AWS environment.

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Whitespace Padding in Process Command Line

Identifies process execution events where the command line value contains a long sequence of whitespace characters or multiple occurrences of contiguous whitespace. Attackers may attempt to evade signature-based detections by padding their malicious command with unnecessary whitespace characters. These observations should be investigated for malicious behavior.

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Webshell Detection: Script Process Child of Common Web Processes

Identifies suspicious commands executed via a web server, which may suggest a vulnerability and remote shell access.

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Web Application Suspicious Activity: POST Request Declined

A POST request to a web application returned a 403 response, which indicates the web application declined to process the request because the action requested was not allowed.

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Web Application Suspicious Activity: Unauthorized Method

A request to a web application returned a 405 response, which indicates the web application declined to process the request because the HTTP method is not allowed for the resource.

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Suspicious JAR Child Process

Identifies suspicious child processes of a Java Archive (JAR) file. JAR files may be used to deliver malware in order to evade detection.

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Bash Shell Profile Modification

Both ~/.bash_profile and ~/.bashrc are files containing shell commands that are run when Bash is invoked. These files are executed in a user’s context, either interactively or non-interactively, when a user logs in so that their environment is set correctly. Adversaries may abuse this to establish persistence by executing malicious content triggered by a user’s shell.

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AWS EC2 Full Network Packet Capture Detected

Identifies potential Traffic Mirroring in an Amazon Elastic Compute Cloud (EC2) instance. Traffic Mirroring is an Amazon VPC feature that you can use to copy network traffic from an Elastic network interface. This feature can potentially be abused to exfiltrate sensitive data from unencrypted internal traffic.

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AWS RDS Security Group Deletion

Identifies the deletion of an Amazon Relational Database Service (RDS) Security group.

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Spike in AWS Error Messages

A machine learning job detected a significant spike in the rate of a particular error in the CloudTrail messages. Spikes in error messages may accompany attempts at privilege escalation, lateral movement, or discovery.

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Rare AWS Error Code

A machine learning job detected an unusual error in a CloudTrail message. These can be byproducts of attempted or successful persistence, privilege escalation, defense evasion, discovery, lateral movement, or collection.

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Unusual City For an AWS Command

A machine learning job detected AWS command activity that, while not inherently suspicious or abnormal, is sourcing from a geolocation (city) that is unusual for the command. This can be the result of compromised credentials or keys being used by a threat actor in a different geography than the authorized user(s).

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Unusual Country For an AWS Command

A machine learning job detected AWS command activity that, while not inherently suspicious or abnormal, is sourcing from a geolocation (country) that is unusual for the command. This can be the result of compromised credentials or keys being used by a threat actor in a different geography than the authorized user(s).

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Unusual AWS Command for a User

A machine learning job detected an AWS API command that, while not inherently suspicious or abnormal, is being made by a user context that does not normally use the command. This can be the result of compromised credentials or keys as someone uses a valid account to persist, move laterally, or exfiltrate data.

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AWS RDS Security Group Creation

Identifies the creation of an Amazon Relational Database Service (RDS) Security group.

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Azure Active Directory High Risk Sign-in

Identifies high risk Azure Active Directory (AD) sign-ins by leveraging Microsoft’s Identity Protection machine learning and heuristics. Identity Protection categorizes risk into three tiers: low, medium, and high. While Microsoft does not provide specific details about how risk is calculated, each level brings higher confidence that the user or sign-in is compromised.

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Application Added to Google Workspace Domain

Detects when a Google marketplace application is added to the Google Workspace domain. An adversary may add a malicious application to an organization’s Google Workspace domain in order to maintain a presence in their target’s organization and steal data.

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Domain Added to Google Workspace Trusted Domains

Detects when a domain is added to the list of trusted Google Workspace domains. An adversary may add a trusted domain in order to collect and exfiltrate data from their target’s organization with less restrictive security controls.

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Google Workspace Admin Role Deletion

Detects when a custom admin role is deleted. An adversary may delete a custom admin role in order to impact the permissions or capabilities of system administrators.

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Google Workspace MFA Enforcement Disabled

Detects when multi-factor authentication (MFA) enforcement is disabled for Google Workspace users. An adversary may disable MFA enforcement in order to weaken an organization’s security controls.

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Google Workspace Password Policy Modified

Detects when a Google Workspace password policy is modified. An adversary may attempt to modify a password policy in order to weaken an organization’s security controls.

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MFA Disabled for Google Workspace Organization

Detects when multi-factor authentication (MFA) is disabled for a Google Workspace organization. An adversary may attempt to modify a password policy in order to weaken an organization’s security controls.

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Google Workspace Admin Role Assigned to a User

Detects when an admin role is assigned to a Google Workspace user. An adversary may assign an admin role to a user in order to elevate the permissions of another user account and persist in their target’s environment.

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Google Workspace API Access Granted via Domain-Wide Delegation of Authority

Detects when a domain-wide delegation of authority is granted to a service account. Domain-wide delegation can be configured to grant third-party and internal applications to access the data of Google Workspace users. An adversary may configure domain-wide delegation to maintain access to their target’s data.

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Google Workspace Custom Admin Role Created

Detects when a custom admin role is created in Google Workspace. An adversary may create a custom admin role in order to elevate the permissions of other user accounts and persist in their target’s environment.

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Google Workspace Role Modified

Detects when a custom admin role or its permissions are modified. An adversary may modify a custom admin role in order to elevate the permissions of other user accounts and persist in their target’s environment.

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O365 Excessive Single Sign-On Logon Errors

Identifies accounts with a high number of single sign-on (SSO) logon errors. Excessive logon errors may indicate an attempt to brute force a password or SSO token.

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Modification of Dynamic Linker Preload Shared Object

Identifies modification of the dynamic linker preload shared object (ld.so.preload). Adversaries may execute malicious payloads by hijacking the dynamic linker used to load libraries.

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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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macOS Installer Spawns Network Event

Identifies when the built in macOS Installer program generates a network event after attempting to install a .pkg file. This activity has been observed being leveraged by malware.

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Persistence via Docker Shortcut Modification

An adversary can establish persistence by modifying an existing macOS dock property list in order to execute a malicious application instead of the intended one when invoked.

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Finder Sync Plugin Registered and Enabled

Finder Sync plugins enable users to extend Finder’s functionality by modifying the user interface. Adversaries may abuse this feature by adding a rogue Finder Plugin to repeatedly execute malicious payloads for persistence.

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Spike in Network Traffic

A machine learning job detected an unusually large spike in network traffic. Such a burst of traffic, if not caused by a surge in business activity, can be due to suspicious or malicious activity. Large-scale data exfiltration may produce a burst of network traffic; this could also be due to unusually large amounts of reconnaissance or enumeration traffic. Denial-of-service attacks or traffic floods may also produce such a surge in traffic.

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Anomalous Linux Compiler Activity

Looks for compiler activity by a user context which does not normally run compilers. This can be the result of ad-hoc software changes or unauthorized software deployment. This can also be due to local privilege elevation via locally run exploits or malware activity.

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Anomalous Kernel Module Activity

Looks for unusual kernel module activity. Kernel modules are sometimes used by malware and persistence mechanisms for stealth.

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Unusual Linux Network Activity

Identifies Linux processes that do not usually use the network but have unexpected network activity, which can indicate command-and-control, lateral movement, persistence, or data exfiltration activity. A process with unusual network activity can denote process exploitation or injection, where the process is used to run persistence mechanisms that allow a malicious actor remote access or control of the host, data exfiltration, and execution of unauthorized network applications.

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Anomalous Process For a Linux Population

Searches for rare processes running on multiple Linux hosts in an entire fleet or network. This reduces the detection of false positives since automated maintenance processes usually only run occasionally on a single machine but are common to all or many hosts in a fleet.

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Unusual Linux Username

A machine learning job detected activity for a username that is not normally active, which can indicate unauthorized changes, activity by unauthorized users, lateral movement, or compromised credentials. In many organizations, new usernames are not often created apart from specific types of system activities, such as creating new accounts for new employees. These user accounts quickly become active and routine. Events from rarely used usernames can point to suspicious activity. Additionally, automated Linux fleets tend to see activity from rarely used usernames only when personnel log in to make authorized or unauthorized changes, or threat actors have acquired credentials and log in for malicious purposes. Unusual usernames can also indicate pivoting, where compromised credentials are used to try and move laterally from one host to another.

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Unusual Process For a Linux Host

Identifies rare processes that do not usually run on individual hosts, which can indicate execution of unauthorized services, malware, or persistence mechanisms. Processes are considered rare when they only run occasionally as compared with other processes running on the host.

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Unusual Process For a Windows Host

Identifies rare processes that do not usually run on individual hosts, which can indicate execution of unauthorized services, malware, or persistence mechanisms. Processes are considered rare when they only run occasionally as compared with other processes running on the host.

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Unusual Windows Network Activity

Identifies Windows processes that do not usually use the network but have unexpected network activity, which can indicate command-and-control, lateral movement, persistence, or data exfiltration activity. A process with unusual network activity can denote process exploitation or injection, where the process is used to run persistence mechanisms that allow a malicious actor remote access or control of the host, data exfiltration, and execution of unauthorized network applications.

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Anomalous Process For a Windows Population

Searches for rare processes running on multiple hosts in an entire fleet or network. This reduces the detection of false positives since automated maintenance processes usually only run occasionally on a single machine but are common to all or many hosts in a fleet.

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Unusual Windows Username

A machine learning job detected activity for a username that is not normally active, which can indicate unauthorized changes, activity by unauthorized users, lateral movement, or compromised credentials. In many organizations, new usernames are not often created apart from specific types of system activities, such as creating new accounts for new employees. These user accounts quickly become active and routine. Events from rarely used usernames can point to suspicious activity. Additionally, automated Linux fleets tend to see activity from rarely used usernames only when personnel log in to make authorized or unauthorized changes, or threat actors have acquired credentials and log in for malicious purposes. Unusual usernames can also indicate pivoting, where compromised credentials are used to try and move laterally from one host to another.

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Default Cobalt Strike Team Server Certificate

This rule detects the use of the default Cobalt Strike Team Server TLS certificate. Cobalt Strike is software for Adversary Simulations and Red Team Operations which are security assessments that replicate the tactics and techniques of an advanced adversary in a network. Modifications to the Packetbeat configuration can be made to include MD5 and SHA256 hashing algorithms (the default is SHA1). See the References section for additional information on module configuration.

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DNS Activity to the Internet

This rule detects when an internal network client sends DNS traffic directly to the Internet. This is atypical behavior for a managed network and can be indicative of malware, exfiltration, command and control, or simply misconfiguration. This DNS activity also impacts your organization’s ability to provide enterprise monitoring and logging of DNS and it opens your network to a variety of abuses and malicious communications.

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Roshal Archive (RAR) or PowerShell File Downloaded from the Internet

Detects a Roshal Archive (RAR) file or PowerShell script downloaded from the internet by an internal host. Gaining initial access to a system and then downloading encoded or encrypted tools to move laterally is a common practice for adversaries as a way to protect their more valuable tools and TTPs (tactics, techniques, and procedures). This may be atypical behavior for a managed network and can be indicative of malware, exfiltration, or command and control.

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RDP (Remote Desktop Protocol) from the Internet

This rule detects network events that may indicate the use of RDP traffic from the Internet. RDP is commonly used by system administrators to remotely control a system for maintenance or to use shared resources. 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.

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Telnet Port Activity

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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VNC (Virtual Network Computing) from the Internet

This rule detects network events that may indicate the use of VNC traffic from the Internet. VNC is commonly used by system administrators to remotely control a system for maintenance or to use shared resources. 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.

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VNC (Virtual Network Computing) to the Internet

This rule detects network events that may indicate the use of VNC traffic to the Internet. VNC is commonly used by system administrators to remotely control a system for maintenance or to use shared resources. 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.

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RPC (Remote Procedure Call) from the Internet

This rule detects network events that may indicate the use of RPC traffic from the Internet. RPC is commonly used by system administrators to remotely control a system for maintenance or to use shared resources. 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.

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RPC (Remote Procedure Call) to the Internet

This rule detects network events that may indicate the use of RPC traffic to the Internet. RPC is commonly used by system administrators to remotely control a system for maintenance or to use shared resources. 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.

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SMB (Windows File Sharing) Activity to the Internet

This rule detects network events that may indicate the use of Windows file sharing (also called SMB or CIFS) traffic to the Internet. SMB is commonly used within networks to share files, printers, and other system resources amongst trusted systems. 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 or for data exfiltration.

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Exporting Exchange Mailbox via PowerShell

Identifies the use of the Exchange PowerShell cmdlet, New-MailBoxExportRequest, to export the contents of a primary mailbox or archive to a .pst file. Adversaries may target user email to collect sensitive information.

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New ActiveSyncAllowedDeviceID Added via PowerShell

Identifies the use of the Exchange PowerShell cmdlet, Set-CASMailbox, to add a new ActiveSync allowed device. Adversaries may target user email to collect sensitive information.

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NTDS or SAM Database File Copied

Identifies a copy operation of the Active Directory Domain Database (ntds.dit) or Security Account Manager (SAM) files. Those files contain sensitive information including hashed domain and/or local credentials.

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Modification of AmsiEnable Registry Key

JScript tries to query the AmsiEnable registry key from the HKEY_USERS registry hive before initializing Antimalware Scan Interface (AMSI). If this key is set to 0, AMSI is not enabled for the JScript process. An adversary can modify this key to disable AMSI protections.

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Windows Defender Disabled via Registry Modification

Identifies modifications to the Windows Defender registry settings to disable the service or set the service to be started manually.

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Windows Defender Exclusions Added via PowerShell

Identifies modifications to the Windows Defender configuration settings using PowerShell to add exclusions at the folder directory or process level.

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Mshta Making Network Connections

Identifies Mshta.exe making outbound network connections. This may indicate adversarial activity, as Mshta is often leveraged by adversaries to execute malicious scripts and evade detection.

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Windows Network Enumeration

Identifies attempts to enumerate hosts in a network using the built-in Windows net.exe tool.

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External IP Lookup from Non-Browser Process

Identifies domains commonly used by adversaries for post-exploitation IP lookups. It is common for adversaries to test for Internet access and acquire their external IP address after they have gained access to a system. Among others, this has been observed in campaigns leveraging the information stealer, Trickbot.

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Execution of File Written or Modified by Microsoft Office

Identifies an executable created by a Microsoft Office application and subsequently executed. These processes are often launched via scripts inside documents or during exploitation of Microsoft Office applications.

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Suspicious WMI Image Load from MS Office

Identifies a suspicious image load (wmiutils.dll) from Microsoft Office processes. This behavior may indicate adversarial activity where child processes are spawned via Windows Management Instrumentation (WMI). This technique can be used to execute code and evade traditional parent/child processes spawned from Microsoft Office products.

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Disabling User Account Control via Registry Modification

User Account Control (UAC) can help mitigate the impact of malware on Windows hosts. With UAC, apps and tasks always run in the security context of a non-administrator account, unless an administrator specifically authorizes administrator-level access to the system. This rule identifies registry value changes to bypass User Access Control (UAC) protection.

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UAC Bypass Attempt with IEditionUpgradeManager Elevated COM Interface

Identifies attempts to bypass User Account Control (UAC) by abusing an elevated COM Interface to launch a rogue Windows ClipUp program. Attackers may attempt to bypass UAC to stealthily execute code with elevated permissions.

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UAC Bypass Attempt via Elevated COM Internet Explorer Add-On Installer

Identifies User Account Control (UAC) bypass attempts by abusing an elevated COM Interface to launch a malicious program. Attackers may attempt to bypass UAC to stealthily execute code with elevated permissions.

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UAC Bypass via ICMLuaUtil Elevated COM Interface

Identifies User Account Control (UAC) bypass attempts via the ICMLuaUtil Elevated COM interface. Attackers may attempt to bypass UAC to stealthily execute code with elevated permissions.

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UAC Bypass via DiskCleanup Scheduled Task Hijack

Identifies User Account Control (UAC) bypass via hijacking DiskCleanup Scheduled Task. Attackers bypass UAC to stealthily execute code with elevated permissions.

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UAC Bypass Attempt via Privileged IFileOperation COM Interface

Identifies attempts to bypass User Account Control (UAC) via DLL side-loading. Attackers may attempt to bypass UAC to stealthily execute code with elevated permissions.

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Bypass UAC via Event Viewer

Identifies User Account Control (UAC) bypass via eventvwr.exe. Attackers bypass UAC to stealthily execute code with elevated permissions.

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UAC Bypass Attempt via Windows Directory Masquerading

Identifies an attempt to bypass User Account Control (UAC) by masquerading as a Microsoft trusted Windows directory. Attackers may bypass UAC to stealthily execute code with elevated permissions.

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UAC Bypass via Windows Firewall Snap-In Hijack

Identifies attempts to bypass User Account Control (UAC) by hijacking the Microsoft Management Console (MMC) Windows Firewall snap-in. Attackers bypass UAC to stealthily execute code with elevated permissions.

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Unusual Parent-Child Relationship

Identifies Windows programs run from unexpected parent processes. This could indicate masquerading or other strange activity on a system.

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