EXPLORE DETECTIONS
Linux Impair Defenses Process Kill
The following analytic identifies the execution of the 'pkill' command, which is used to terminate processes on a Linux system. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process names and command-line executions. This activity is significant because threat actors often use 'pkill' to disable security defenses or terminate critical processes, facilitating further malicious actions. If confirmed malicious, this behavior could lead to the disruption of security applications, enabling attackers to evade detection and potentially corrupt or destroy files on the targeted system.
Linux Indicator Removal Clear Cache
The following analytic detects processes that clear or free page cache on a Linux system. It leverages Endpoint Detection and Response (EDR) data, focusing on specific command-line executions involving the kernel system request `drop_caches`. This activity is significant as it may indicate an attempt to delete forensic evidence or the presence of wiper malware like Awfulshred. If confirmed malicious, this behavior could allow an attacker to cover their tracks, making it difficult to investigate other malicious activities or system compromises.
Linux Indicator Removal Service File Deletion
The following analytic detects the deletion of Linux service unit configuration files by suspicious processes. It leverages Endpoint Detection and Response (EDR) telemetry, focusing on processes executing the 'rm' command targeting '.service' files. This activity is significant as it may indicate malware attempting to disable critical services or security products, a common defense evasion tactic. If confirmed malicious, this behavior could lead to service disruption, security tool incapacitation, or complete system compromise, severely impacting the integrity and availability of the affected Linux host.
Linux Ingress Tool Transfer Hunting
The following analytic detects the use of 'curl' and 'wget' commands within a Linux environment. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process names, user information, and command-line executions. This activity is significant as 'curl' and 'wget' are commonly used for downloading files, which can indicate potential ingress of malicious tools. If confirmed malicious, this activity could lead to unauthorized code execution, data exfiltration, or further compromise of the system. Monitoring and tuning this detection helps identify and differentiate between normal and potentially harmful usage.
Linux Ingress Tool Transfer with Curl
The following analytic detects the use of the curl command with specific switches (-O, -sO, -ksO, --output) commonly used to download remote scripts or binaries. This detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on process names and command-line arguments. This activity is significant as it may indicate an attempt to download and execute potentially malicious files, often used in initial stages of an attack. If confirmed malicious, this could lead to unauthorized code execution, enabling attackers to compromise the system further.
Linux Insert Kernel Module Using Insmod Utility
The following analytic detects the insertion of a Linux kernel module using the insmod utility. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process execution logs that include process names and command-line details. This activity is significant as it may indicate the installation of a rootkit or malicious kernel module, potentially allowing an attacker to gain elevated privileges and bypass security detections. If confirmed malicious, this could lead to unauthorized code execution, persistent access, and severe compromise of the affected system.
Linux Install Kernel Module Using Modprobe Utility
The following analytic detects the installation of a Linux kernel module using the modprobe utility. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process names and command-line executions. This activity is significant because installing a kernel module can indicate an attempt to deploy a rootkit or other malicious kernel-level code, potentially leading to elevated privileges and bypassing security detections. If confirmed malicious, this could allow an attacker to gain persistent, high-level access to the system, compromising its integrity and security.
Linux Iptables Firewall Modification
The following analytic detects suspicious command-line activity that modifies the iptables firewall settings on a Linux machine. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on specific command patterns that alter firewall rules to accept traffic on certain TCP ports. This activity is significant as it can indicate malware, such as CyclopsBlink, modifying firewall settings to allow communication with a Command and Control (C2) server. If confirmed malicious, this could enable attackers to maintain persistent access and exfiltrate data, posing a severe security risk.
Linux Kernel Module Enumeration
The following analytic identifies the use of the 'kmod' process to list kernel modules on a Linux system. This detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on process names and command-line executions. While listing kernel modules is not inherently malicious, it can be a precursor to loading unauthorized modules using 'insmod'. If confirmed malicious, this activity could allow an attacker to load kernel modules, potentially leading to privilege escalation, persistence, or other malicious actions within the system.
Linux Kworker Process In Writable Process Path
The following analytic detects the execution of a kworker process with a command line in writable directories such as /home/, /var/log, and /tmp on a Linux machine. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process and parent process paths. This activity is significant as kworker processes are typically kernel threads, and their presence in writable directories is unusual and indicative of potential malware, such as CyclopsBlink. If confirmed malicious, this could allow attackers to blend malicious processes with legitimate ones, leading to persistent access and further system compromise.
Linux Magic SysRq Key Abuse
Detects potential abuse of the Linux Magic SysRq (System Request) key by adversaries with root or sufficient privileges to manipulate or destabilize a system. Writing to /proc/sysrq-trigger can crash the system, kill processes, or bypass standard logging. Monitoring SysRq abuse helps detect stealthy post-exploitation activity. Correlate with related EXECVE or PROCTITLE events to identify the process or user responsible for the access or modification.
Linux Make Privilege Escalation
The following analytic detects the use of the 'make' command with elevated privileges to execute system commands as root, potentially leading to a root shell. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on command-line executions that include 'make', '--eval', and 'sudo'. This activity is significant because it indicates a possible privilege escalation attempt, allowing a user to gain root access. If confirmed malicious, an attacker could achieve full control over the system, execute arbitrary commands, and compromise the entire environment.
Linux Medusa Rootkit
This detection identifies file creation events associated with the installation of the Medusa rootkit, a userland LD_PRELOAD-based rootkit known for deploying shared objects, loader binaries, and configuration files into specific system directories. These files typically facilitate process hiding, credential theft, and backdoor access. Monitoring for such file creation patterns enables early detection of rootkit deployment before full compromise.
Linux MySQL Privilege Escalation
The following analytic detects the execution of MySQL commands with elevated privileges using sudo, which can lead to privilege escalation. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process execution logs that include command-line details. This activity is significant because it indicates a potential misuse of MySQL to execute system commands as root, which could allow an attacker to gain root shell access. If confirmed malicious, this could result in full control over the affected system, leading to severe security breaches and unauthorized access to sensitive data.
Linux Ngrok Reverse Proxy Usage
The following analytic detects the use of Ngrok on a Linux operating system. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process names and command-line arguments associated with Ngrok. This activity is significant because Ngrok can be used by adversaries to establish reverse proxies, potentially bypassing network defenses. If confirmed malicious, this could allow attackers to create persistent, unauthorized access channels, facilitating data exfiltration or further exploitation of the compromised system.
Linux Node Privilege Escalation
The following analytic identifies the execution of Node.js with elevated privileges using sudo, specifically when spawning child processes. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on command-line executions that include specific Node.js commands. This activity is significant because running Node.js as a superuser without dropping privileges can allow unauthorized access to the file system and potential privilege escalation. If confirmed malicious, this could enable an attacker to maintain privileged access, execute arbitrary code, and compromise sensitive data within the environment.
Linux NOPASSWD Entry In Sudoers File
The following analytic detects the addition of NOPASSWD entries to the /etc/sudoers file on Linux systems. It leverages Endpoint Detection and Response (EDR) telemetry to identify command lines containing "NOPASSWD:". This activity is significant because it allows users to execute commands with elevated privileges without requiring a password, which can be exploited by adversaries to maintain persistent, privileged access. If confirmed malicious, this could lead to unauthorized privilege escalation, persistent access, and potential compromise of sensitive data and system integrity.
Linux Obfuscated Files or Information Base64 Decode
The following analytic detects the use of the base64 decode command on Linux systems, which is often used to deobfuscate files. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on command-line executions that include "base64 -d" or "base64 --decode". This activity is significant as it may indicate an attempt to hide malicious payloads or scripts. If confirmed malicious, an attacker could use this technique to execute hidden code, potentially leading to unauthorized access, data exfiltration, or further system compromise.
Linux Octave Privilege Escalation
The following analytic detects the execution of GNU Octave with elevated privileges, specifically when it runs system commands via sudo. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process command-line arguments that include "octave-cli," "--eval," "system," and "sudo." This activity is significant because it indicates a potential privilege escalation attempt, allowing a user to execute commands as root. If confirmed malicious, this could lead to full system compromise, enabling an attacker to gain root access and execute arbitrary commands, severely impacting system security and integrity.
Linux OpenVPN Privilege Escalation
The following analytic detects the execution of OpenVPN with elevated privileges, specifically when combined with the `--dev`, `--script-security`, `--up`, and `sudo` options. This detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on process command-line arguments and execution details. This activity is significant because it indicates a potential privilege escalation attempt, allowing a user to execute system commands as root. If confirmed malicious, this could lead to full system compromise, enabling an attacker to gain root access and execute arbitrary commands with elevated privileges.
Linux Persistence and Privilege Escalation Risk Behavior
The following analytic identifies potential Linux persistence and privilege escalation activities. It leverages risk scores and event counts from various Linux-related data sources, focusing on tactics associated with persistence and privilege escalation. This activity is significant for a SOC because it highlights behaviors that could allow an attacker to maintain access or gain elevated privileges on a Linux system. If confirmed malicious, this activity could enable an attacker to execute code with higher privileges, persist in the environment, and potentially access sensitive information, posing a severe security risk.
Linux PHP Privilege Escalation
The following analytic detects the execution of PHP commands with elevated privileges on a Linux system. It identifies instances where PHP is used in conjunction with 'sudo' and 'system' commands, indicating an attempt to run system commands as the root user. This detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on process command-line arguments. This activity is significant because it can indicate an attempt to escalate privileges, potentially leading to full root access. If confirmed malicious, this could allow an attacker to execute arbitrary commands with root privileges, compromising the entire system.
Linux pkexec Privilege Escalation
The following analytic detects the execution of `pkexec` without any command-line arguments. This behavior leverages data from Endpoint Detection and Response (EDR) agents, focusing on process telemetry. The significance lies in the fact that this pattern is associated with the exploitation of CVE-2021-4034 (PwnKit), a critical vulnerability in Polkit's pkexec component. If confirmed malicious, this activity could allow an attacker to gain full root privileges on the affected Linux system, leading to complete system compromise and potential unauthorized access to sensitive information.
Linux Possible Access Or Modification Of sshd Config File
The following analytic detects suspicious access or modification of the sshd_config file on Linux systems. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on command-line executions involving processes like "cat," "nano," "vim," and "vi" accessing the sshd_config file. This activity is significant because unauthorized changes to sshd_config can allow threat actors to redirect port connections or use unauthorized keys, potentially compromising the system. If confirmed malicious, this could lead to unauthorized access, privilege escalation, or persistent backdoor access, posing a severe security risk.