Detections

Explore public detection logic contributed by the community across SIEM and rule languages.

7,138 detections

This analytic detects the suspicious disable or modification of system firewalls on Linux systems. Specifically, it looks for `SERVICE_STOP` events for `firewalld` or `ufw` units. This behavior is critical to monitor as it may indicate attempts to gain unauthorized access or maintain control over a system by bypassing network controls. Such actions could be signs of malicious activity, potentially leading to a compromised system, unauthorized access to sensitive data, or a wider network breach. Early detection and response are essential to prevent potential security incidents.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
0029
The analytic detects suspicious stopping of the `osquery` service, which may indicate an attempt to disable monitoring and evade detection. `Osquery` is a powerful tool used for querying system information and detecting anomalies, and stopping its service can be a sign that an attacker is trying to disrupt security monitoring or hide malicious activities. By monitoring for unusual or unauthorized stops of the `osquery` service, this analytic helps identify potential efforts to bypass security controls, enabling security teams to investigate and respond to possible threats effectively.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
0029
The following analytic detects suspicious preload hijacking via the `preload` file, which may indicate an attacker's attempt to intercept or manipulate library loading processes. The `preload` file can be used to force the loading of specific libraries before others, potentially allowing malicious code to execute or alter application behavior. By monitoring for unusual or unauthorized modifications to the `preload` file, this analytic helps identify attempts to hijack preload mechanisms, enabling security teams to investigate and address potential threats to system integrity and security.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
0028
This rule detects attempts to hijack the Amazon SSM Agent on Linux systems. Specifically, it looks for the 'amazon-ssm-agent' executable being run with command-line arguments indicative of registration with a new code, ID, and region. This behavior is consistent with the technique described in the Mitiga research report where the SSM agent can be abused as a remote access trojan for persistence and command and control.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
1 year ago
0020
Detects suspicious use of command-line tools such as curl or wget to download remote
content - particularly scripts - into temporary directories (e.g., /dev/shm, /tmp), followed by
immediate execution, indicating potential malicious activity. This pattern is commonly used
by malicious scripts, stagers, or downloaders in fileless or multi-stage Linux attacks.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
1 year ago
000
The following analytic detects command-line activities that redirect stdout or stderr to the /dev/null file. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process execution logs. This behavior is significant as it can indicate attempts to hide command outputs, a technique observed in the CyclopsBlink malware to conceal modifications to iptables firewall settings. If confirmed malicious, this activity could allow an attacker to stealthily alter system configurations, potentially leading to unauthorized access or persistent control over the compromised machine.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
0034
The analytic identifies potential exploitation attempts on a PaperCut NG server by analyzing its debug log data. It detects unauthorized or suspicious access attempts from public IP addresses and searches for specific URIs associated with known exploits. The detection leverages regex to parse unstructured log data, focusing on admin login activities. This activity is significant as it can indicate an active exploitation attempt on the server. If confirmed malicious, attackers could gain unauthorized access, potentially leading to data breaches or further compromise of the server.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
1030
Detects the use of command-line tools such as 'scp', 'rsync', and 'sftp' that are commonly used to copy files to or from remote systems. This activity can be indicative of an adversary transferring tools into an environment (Ingress Tool Transfer) or moving files laterally within a compromised network (Lateral Tool Transfer). The rule specifically looks for the presence of these tool names followed by a space and then a colon or an '@' symbol, which are characteristic of remote file operations.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
1 year ago
2068
Detects the use of the `syslog` syscall with action codes 4, 5, or 6, which can clear or disable the kernel ring buffer (dmesg logs). This technique can be used by attackers to hide traces after exploitation or privilege escalation. A common method is running `dmesg -c`, which internally triggers this syscall.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
1 year ago
2033
This rule detects attempts to enumerate local system groups on Linux. Adversaries often perform this discovery technique to understand the environment and identify users with elevated permissions. The rule triggers on execution of the 'groups' command or on common file viewing utilities (cat, ed, head, less, more, nano, tail, vi, vim) when they are used to read the '/etc/group' file.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
1 year ago
1028
This rule detects the execution or creation of files identified as Remote Access Tools (RATs) based on a Google Cloud Threat Intelligence (GCTI) feed. It correlates process launch, module load, or file creation events with known SHA256 hashes of RATs provided by the GCTI feed. The rule specifically looks for events where the SHA256 hash of the process or file matches a hash from the 'Remote Access Tools' threat feed within the GCTI graph.
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Google SecOps@GoogleSecOps
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Google SecOps Detection Rules
1 year ago
2073
Detects the execution of common text-based file access or inspection utilities to read the content of the '/etc/sudoers' file on Linux systems. This activity is often performed by adversaries to discover users with sudo rights, which can be a precursor to privilege escalation.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
1 year ago
2027
Detects attempts to record audio using the `arecord` and `ecasound` utilities on Linux systems. This rule specifically looks for the execution of `arecord` with common audio recording flags (`-vv`, `-fdat`) or the `ecasound` utility making a `memfd_create` syscall, which could indicate audio processing or recording.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
1 year ago
0026
This rule detects when a file, identified as malicious by Google Safe Browsing, initiates an outbound network connection to an IP address known to be a Tor Exit Node, as identified by Google Cloud Threat Intelligence (GCTI) Feed. This indicates potential command and control (C2) communication or data exfiltration by malware attempting to anonymize its network traffic.
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Google SecOps@GoogleSecOps
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Google SecOps Detection Rules
1 year ago
0063
Detects possible command execution by a web application or web shell by monitoring `execve` and `execveat` syscalls initiated by the web server's user ID (e.g., euid 33 for www-data). This rule specifically targets Linux systems using auditd for logging, requiring a specific auditd configuration to capture these events.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
1 year ago
3024
This rule detects outbound network connections to IP addresses that have been observed for the first time within the last 24 hours. It specifically excludes connections to private IP address ranges (RFC1918). The detection relies on correlating current network connection events with historical 'first seen' data for IP addresses from an entity graph.
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Google SecOps@GoogleSecOps
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Google SecOps Detection Rules
1 year ago
1061
Detects the use of the `sysinfo` system call in Linux, which provides a snapshot of key system statistics such as uptime, load averages, memory usage, and the number of running processes. Malware or reconnaissance tools might leverage `sysinfo` to fingerprint the system, gathering data to determine if it's a viable target.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
1 year ago
3023
This rule detects outbound network connections to IP addresses that exhibit low prevalence within the monitored environment. Specifically, it flags connections to IPs that have a rolling maximum prevalence of 1 to 3 occurrences over a 10-day period. This behavior can be indicative of command and control (C2) communication, data exfiltration, or other suspicious activities where adversaries might use newly registered or rarely seen infrastructure.
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Google SecOps@GoogleSecOps
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Google SecOps Detection Rules
1 year ago
1051
This rule detects outbound network connections to known Tor exit nodes. It leverages a Google Cloud Threat Intelligence (GCTI) feed that provides a list of current Tor exit node IP addresses. The rule specifically looks for allowed network connections where the target IP address is identified as a Tor exit node by the GCTI feed. This can indicate an attempt to anonymize network traffic, which is often associated with malicious activity.
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Google SecOps@GoogleSecOps
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Google SecOps Detection Rules
1 year ago
1050
Detects the execution of host or user discovery utilities such as "whoami", "hostname", "id", "last", "uname", "users", "w", and "who" on Linux systems. Adversaries use these commands to gather information about the system and its users to inform subsequent actions.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
1 year ago
2019
Detects the creation of a process that includes environment variables for HTTP or HTTPS proxy settings in its command line. This can indicate an attempt to route network traffic through a proxy, potentially for command and control or to bypass network restrictions.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
1 year ago
1023
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