Update v8.7.4

Potential Linux Credential Dumping via Proc Filesystem

Identifies the execution of the mimipenguin exploit script which is linux adaptation of Windows tool mimikatz. Mimipenguin exploit script is used to dump clear text passwords from a currently logged-in user. The tool exploits a known vulnerability CVE-2018-20781. Malicious actors can exploit the cleartext credentials in memory by dumping the process and extracting lines that have a high probability of containing cleartext passwords.

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Suspicious File Changes Activity Detected

Ransomware is a type of malware that encrypts a victim’s files or systems and demands payment (usually in cryptocurrency) in exchange for the decryption key. One important indicator of a ransomware attack is the mass encryption of the file system, after which a new file extension is added to the file. This rule identifies a sequence of 50 file extension rename events by the same process in a timespan of 1 second.

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Potential Linux Ransomware Note Creation Detected

Ransomware is a type of malware that encrypts a victim’s files or systems and demands payment (usually in cryptocurrency) in exchange for the decryption key. One important indicator of a ransomware attack is the mass encryption of the file system, after which a new file extension is added to the file. Generally, a ransomware note with contact details is dropped onto the file system which can be used by the victim to contact the attacker. This rule identifies a sequence of a mass file encryption event in conjunction with the creation of a .txt file with a file name containing ransomware keywords executed by the same process in a 1 second timespan.

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Potential Persistence Through init.d Detected

Files that are placed in the /etc/init.d/ directory in Unix can be used to start custom applications, services, scripts or commands during start-up. Init.d has been mostly replaced in favor of Systemd, however, through the "systemd-sysv-generator" init.d files can be converted to service unit files that run at boot. Adversaries may add or alter files located in the /etc/init.d/ directory to execute malicious code on boot time in order to gain persistence onto the system.

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Potential Remote Code Execution via Web Server

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

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Potential Persistence Through MOTD File Creation Detected

Message of the day (MOTD) is the message that is presented to the user when a user connects to a Linux server via SSH or a serial connection. Linux systems contain several default MOTD files located in the "/etc/update-motd.d/" and "/usr/lib/update-notifier/" directories. These scripts run as the root user every time a user connects over SSH or a serial connection. Adversaries may create malicious MOTD files that grant them persistence onto the target every time a user connects to the system by executing a backdoor script or command. This rule detects the creation of potentially malicious files within the default MOTD file directories.

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Suspicious Process Spawned from MOTD Detected

Message of the day (MOTD) is the message that is presented to the user when a user connects to a Linux server via SSH or a serial connection. Linux systems contain several default MOTD files located in the "/etc/update-motd.d/" and "/usr/lib/update-notifier/" directories. These scripts run as the root user every time a user connects over SSH or a serial connection. Adversaries may create malicious MOTD files that grant them persistence onto the target every time a user connects to the system by executing a backdoor script or command. This rule detects the execution of potentially malicious processes through the MOTD utility.

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First Time Seen Commonly Abused Remote Access Tool Execution

Adversaries may install legitimate remote access tools (RAT) to compromised endpoints for further command-and-control (C2). Adversaries can rely on installed RATs for persistence, execution of native commands and more. This rule detects when a process is started whose name or code signature resembles commonly abused RATs. This is a New Terms rule type indicating the host has not seen this RAT process started before within the last 30 days.

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Modification of Standard Authentication Module or Configuration

Adversaries may modify the standard authentication module for persistence via patching the normal authorization process or modifying the login configuration to allow unauthorized access or elevate privileges.

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First Time Seen AWS Secret Value Accessed in Secrets Manager

An adversary equipped with compromised credentials may attempt to access the secrets in secrets manager to steal certificates, credentials, or other sensitive material.

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File made Immutable by Chattr

Detects a file being made immutable using the chattr binary. Making a file immutable means it cannot be deleted or renamed, no link can be created to this file, most of the file’s metadata can not be modified, and the file can not be opened in write mode. Threat actors will commonly utilize this to prevent tampering or modification of their malicious files or any system files they have modified for purposes of persistence (e.g .ssh, /etc/passwd, etc.).

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Abnormal Process ID or Lock File Created

Identifies the creation of a Process ID (PID), lock or reboot file created in temporary file storage paradigm (tmpfs) directory /var/run. On Linux, the PID files typically hold the process ID to track previous copies running and manage other tasks. Certain Linux malware use the /var/run directory for holding data, executables and other tasks, disguising itself or these files as legitimate PID files.

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Suspicious File Creation in /etc for Persistence

Detects the manual creation of files in specific etc directories, via user root, used by Linux malware to persist and elevate privileges on compromised systems. File creation in these directories should not be entirely common and could indicate a malicious binary or script installing persistence for long term access.

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Privileged Account Brute Force

Identifies multiple consecutive logon failures targeting an Admin account from the same source address and within a short time interval. Adversaries will often brute force login attempts across multiple users with a common or known password, in an attempt to gain access to accounts.

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Multiple Logon Failure Followed by Logon Success

Identifies multiple logon failures followed by a successful one from the same source address. Adversaries will often brute force login attempts across multiple users with a common or known password, in an attempt to gain access to accounts.

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Multiple Logon Failure from the same Source Address

Identifies multiple consecutive logon failures from the same source address and within a short time interval. Adversaries will often brute force login attempts across multiple users with a common or known password, in an attempt to gain access to accounts.

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FirstTime Seen Account Performing DCSync

This rule identifies when a User Account starts the Active Directory Replication Process for the first time. Attackers can use the DCSync technique to get credential information of individual accounts or the entire domain, thus compromising the entire domain.

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Potential Credential Access via DCSync

This rule identifies when a User Account starts the Active Directory Replication Process. Attackers can use the DCSync technique to get credential information of individual accounts or the entire domain, thus compromising the entire domain.

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Kerberos Pre-authentication Disabled for User

Identifies the modification of an account’s Kerberos pre-authentication options. An adversary with GenericWrite/GenericAll rights over the account can maliciously modify these settings to perform offline password cracking attacks such as AS-REP roasting.

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Access to a Sensitive LDAP Attribute

Identify access to sensitive Active Directory object attributes that contains credentials and decryption keys such as unixUserPassword, ms-PKI-AccountCredentials and msPKI-CredentialRoamingTokens.

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LSASS Memory Dump Handle Access

Identifies handle requests for the Local Security Authority Subsystem Service (LSASS) object access with specific access masks that many tools with a capability to dump memory to disk use (0x1fffff, 0x1010, 0x120089). This rule is tool agnostic as it has been validated against a host of various LSASS dump tools such as SharpDump, Procdump, Mimikatz, Comsvcs etc. It detects this behavior at a low level and does not depend on a specific tool or dump file name.

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Potential Remote Credential Access via Registry

Identifies remote access to the registry to potentially dump credential data from the Security Account Manager (SAM) registry hive in preparation for credential access and privileges elevation.

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Multiple Vault Web Credentials Read

Windows Credential Manager allows you to create, view, or delete saved credentials for signing into websites, connected applications, and networks. An adversary may abuse this to list or dump credentials stored in the Credential Manager for saved usernames and passwords. This may also be performed in preparation of lateral movement.

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Sensitive Privilege SeEnableDelegationPrivilege assigned to a User

Identifies the assignment of the SeEnableDelegationPrivilege sensitive "user right" to a user. The SeEnableDelegationPrivilege "user right" enables computer and user accounts to be trusted for delegation. Attackers can abuse this right to compromise Active Directory accounts and elevate their privileges.

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Potential Shadow Credentials added to AD Object

Identify the modification of the msDS-KeyCredentialLink attribute in an Active Directory Computer or User Object. Attackers can abuse control over the object and create a key pair, append to raw public key in the attribute, and obtain persistent and stealthy access to the target user or computer object.

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User account exposed to Kerberoasting

Detects when a user account has the servicePrincipalName attribute modified. Attackers can abuse write privileges over a user to configure Service Principle Names (SPNs) so that they can perform Kerberoasting. Administrators can also configure this for legitimate purposes, exposing the account to Kerberoasting.

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Suspicious Remote Registry Access via SeBackupPrivilege

Identifies remote access to the registry using an account with Backup Operators group membership. This may indicate an attempt to exfiltrate credentials by dumping the Security Account Manager (SAM) registry hive in preparation for credential access and privileges elevation.

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Adding Hidden File Attribute via Attrib

Adversaries can add the hidden attribute to files to hide them from the user in an attempt to evade detection.

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Windows Event Logs Cleared

Identifies attempts to clear Windows event log stores. This is often done by attackers in an attempt to evade detection or destroy forensic evidence on a system.

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System Information Discovery via Windows Command Shell

Identifies the execution of discovery commands to enumerate system information, files, and folders using the Windows Command Shell.

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Enumeration of Privileged Local Groups Membership

Identifies instances of an unusual process enumerating built-in Windows privileged local groups membership like Administrators or Remote Desktop users.

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Potential PowerShell HackTool Script by Function Names

Detects known PowerShell offensive tooling functions names in PowerShell scripts. Attackers commonly use out-of-the-box offensive tools without modifying the code. This rule aim is to take advantage of that.

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Remote Windows Service Installed

Identifies a network logon followed by Windows service creation with same LogonId. This could be indicative of lateral movement, but will be noisy if commonly done by administrators."

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Remote Logon followed by Scheduled Task Creation

Identifies a remote logon followed by a scheduled task creation on the target host. This could be indicative of adversary lateral movement.

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AdminSDHolder Backdoor

Detects modifications in the AdminSDHolder object. Attackers can abuse the SDProp process to implement a persistent backdoor in Active Directory. SDProp compares the permissions on protected objects with those defined on the AdminSDHolder object. If the permissions on any of the protected accounts and groups do not match, the permissions on the protected accounts and groups are reset to match those of the domain’s AdminSDHolder object, regaining their Administrative Privileges.

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Account Configured with Never-Expiring Password

Detects the creation and modification of an account with the "Don’t Expire Password" option Enabled. Attackers can abuse this misconfiguration to persist in the domain and maintain long-term access using compromised accounts with this property.

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KRBTGT Delegation Backdoor

Identifies the modification of the msDS-AllowedToDelegateTo attribute to KRBTGT. Attackers can use this technique to maintain persistence to the domain by having the ability to request tickets for the KRBTGT service.

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Account Password Reset Remotely

Identifies an attempt to reset a potentially privileged account password remotely. Adversaries may manipulate account passwords to maintain access or evade password duration policies and preserve compromised credentials.

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Startup or Run Key Registry Modification

Identifies run key or startup key registry modifications. In order to survive reboots and other system interrupts, attackers will modify run keys within the registry or leverage startup folder items as a form of persistence.

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A scheduled task was created

Indicates the creation of a scheduled task using Windows event logs. Adversaries can use these to establish persistence, move laterally, and/or escalate privileges.

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A scheduled task was updated

Indicates the update of a scheduled task using Windows event logs. Adversaries can use these to establish persistence, by changing the configuration of a legit scheduled task. Some changes such as disabling or enabling a scheduled task are common and may may generate noise.

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AdminSDHolder SDProp Exclusion Added

Identifies a modification on the dsHeuristics attribute on the bit that holds the configuration of groups excluded from the SDProp process. The SDProp compares the permissions on protected objects with those defined on the AdminSDHolder object. If the permissions on any of the protected accounts and groups do not match, the permissions on the protected accounts and groups are reset to match those of the domain’s AdminSDHolder object, meaning that groups excluded will remain unchanged. Attackers can abuse this misconfiguration to maintain long-term access to privileged accounts in these groups.

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Suspicious service was installed in the system

Identifies the creation of a new Windows service with suspicious Service command values. Windows services typically run as SYSTEM and can be used for privilege escalation and persistence.

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Temporarily Scheduled Task Creation

Indicates the creation and deletion of a scheduled task within a short time interval. Adversaries can use these to proxy malicious execution via the schedule service and perform clean up.

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User Added to Privileged Group

Identifies a user being added to a privileged group in Active Directory. Privileged accounts and groups in Active Directory are those to which powerful rights, privileges, and permissions are granted that allow them to perform nearly any action in Active Directory and on domain-joined systems.

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Process Creation via Secondary Logon

Identifies process creation with alternate credentials. Adversaries may create a new process with a different token to escalate privileges and bypass access controls.

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Modification of the msPKIAccountCredentials

Identify the modification of the msPKIAccountCredentials attribute in an Active Directory User Object. Attackers can abuse the credentials roaming feature to overwrite an arbitrary file for privilege escalation. ms-PKI-AccountCredentials contains binary large objects (BLOBs) of encrypted credential objects from the credential manager store, private keys, certificates, and certificate requests.

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Startup/Logon Script added to Group Policy Object

Detects the modification of Group Policy Objects (GPO) to add a startup/logon script to users or computer objects.

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Group Policy Abuse for Privilege Addition

Detects the first occurrence of a modification to Group Policy Object Attributes to add privileges to user accounts or use them to add users as local admins.

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Scheduled Task Execution at Scale via GPO

Detects the modification of Group Policy Object attributes to execute a scheduled task in the objects controlled by the GPO.

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Service Creation via Local Kerberos Authentication

Identifies a suspicious local successful logon event where the Logon Package is Kerberos, the remote address is set to localhost, followed by a sevice creation from the same LogonId. This may indicate an attempt to leverage a Kerberos relay attack variant that can be used to elevate privilege locally from a domain joined user to local System privileges.

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Potential Privileged Escalation via SamAccountName Spoofing

Identifies a suspicious computer account name rename event, which may indicate an attempt to exploit CVE-2021-42278 to elevate privileges from a standard domain user to a user with domain admin privileges. CVE-2021-42278 is a security vulnerability that allows potential attackers to impersonate a domain controller via samAccountName attribute spoofing.

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Remote Computer Account DnsHostName Update

Identifies the remote update to a computer account’s DnsHostName attribute. If the new value set is a valid domain controller DNS hostname and the subject computer name is not a domain controller, then it’s highly likely a preparation step to exploit CVE-2022-26923 in an attempt to elevate privileges from a standard domain user to domain admin privileges.

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Windows Service Installed via an Unusual Client

Identifies the creation of a Windows service by an unusual client process. Services may be created with administrator privileges but are executed under SYSTEM privileges, so an adversary may also use a service to escalate privileges from administrator to SYSTEM.

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Potential Shell via Web Server

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

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