Detections

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

918 detections

This query was originally published in the threat analytics report, OSX/SurfBuyer adware campaign.
It will return results if a shell script has furtively attempted to decode and save a file to a /tmp folder.
If discovered on your system, this kind of activity might be associated with SurfBuyer, which is adware that installs a browser extension to take control of several major web browsers, including Safari, Google Chrome, and Firefox.
Azure Sentinel@AzureSentinel
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AzureSentinel
1 year ago
0018
Detects potential command execution via webshell in SAP NetViewer through JSP files with 'cmd' or similar parameters. This rule is designed to identify exploitation of vulnerabilities like CVE-2025-31324, which allows remote code execution via a webshell by looking for specific URI patterns and query parameters indicative of command execution attempts, including common Linux commands and base64 encoded commands.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
1 year ago
0029
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
Detects the potential abuse of the Linux Magic SysRq (System Request) key by adversaries with root or sufficient privileges to silently manipulate or destabilize a system. By writing to /proc/sysrq-trigger, they can crash the system, kill processes, or disrupt forensic analysis—all while bypassing standard logging. Though intended for recovery and debugging, SysRq can be misused as a stealthy post-exploitation tool. It is controlled via /proc/sys/kernel/sysrq or permanently through /etc/sysctl.conf.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
1 year ago
2025
This analytic detects instances where a shell is spawned within a Kubernetes container. Leveraging Falco, a cloud-native runtime security tool, this analytic monitors system calls within the Kubernetes environment and flags when a shell is spawned. This activity is significant for a SOC as it may indicate unauthorized access, allowing an attacker to execute arbitrary commands, manipulate container processes, or escalate privileges. If confirmed malicious, this could lead to data breaches, service disruptions, or unauthorized access to sensitive information, severely impacting the Kubernetes infrastructure's integrity and security.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
2043
This analytic detects the behavior of decoding base64-encoded data and passing it to a Linux shell. The detection is made by searching for specific commands in the Splunk query, namely "base64 -d" and "base64 --decode", within the Endpoint.Processes data model. The analytic also includes a filter for Linux shells. This activity is indicative of malicious behavior as Base64 encoding is commonly used to obfuscate malicious commands or payloads, and decoding it can be a step in running those commands. It suggests that an attacker is attempting to run malicious commands on a Linux system to gain unauthorized access, for data exfiltration, or perform other malicious actions.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
0034
The analytic detects the execution of suspicious bash commands commonly used in scripts like AutoSUID, LinEnum, and LinPeas for system discovery on a Linux host. It leverages Endpoint Detection and Response (EDR) data, specifically looking for a high number of distinct commands executed within a short time frame. This activity is significant as it often precedes privilege escalation or other malicious actions. If confirmed malicious, an attacker could gain detailed system information, identify vulnerabilities, and potentially escalate privileges, posing a severe threat to the environment.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
0033
This analytic detects the execution of BusyBox with sudo privileges, which can lead to privilege escalation on Linux systems. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process creation events where BusyBox is executed with both 'sh' and 'sudo' commands. This activity is significant because it indicates a user may be attempting to gain root access, bypassing standard security controls. If confirmed malicious, this could allow an attacker to execute arbitrary commands as root, leading to full system compromise and potential persistence within the environment.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
0031
The following analytic detects the execution of a command to enable all SysRq functions on a Linux system, a technique associated with the AwfulShred malware. It leverages Endpoint Detection and Response (EDR) data to identify processes executing the command to pipe bitmask '1' to /proc/sys/kernel/sysrq. This activity is significant as it can indicate an attempt to manipulate kernel system requests, which is uncommon and potentially malicious. If confirmed, this could allow an attacker to reboot the system or perform other critical actions, leading to system instability or further compromise.
Splunk Security@SplunkSecurity
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Splunk Security Content
1 year ago
0029
Detects suspicious shell commands commonly used in various exploit codes, including those associated with Apache Struts vulnerabilities and Metasploit framework activities. The rule looks for patterns indicative of downloading and executing scripts, setting up reverse shells, or modifying file permissions for persistence or privilege escalation.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
0051
This rule detects suspicious command-line patterns indicative of reverse shell attempts. It looks for various common techniques used to establish a reverse shell, including bash, sh, netcat, socat, Perl, Python, Ruby, and PHP one-liners that connect back to an attacker-controlled host. The rule also includes patterns for xterm reverse shells and specific shell commands often used in conjunction with reverse shells.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
1046
This rule detects suspicious sub-processes spawned by common web server processes on Linux systems. It specifically looks for web server processes (Apache, Nginx, Lighttpd, Node, Caddy, Tomcat, WebSphere) executing common system utilities and commands such as 'whoami', 'ifconfig', 'ip', 'uname', 'cat', 'crontab', 'hostname', 'iptables', 'netstat', 'pwd', and 'route'. This behavior is indicative of a web shell being used to execute commands on the compromised server.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
4037
Detects suspicious command executions on Linux systems, specifically focusing on modifications to file permissions (chmod 777, chmod u+s) and copying of shell binaries (/bin/ksh, /bin/sh). These actions are often associated with malware or hacking activities, such as privilege escalation or establishing persistence.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
1034
Detects executions of scripts located in potentially suspicious locations such as "/tmp" via a shell such as "bash", "sh", etc. This behavior is often associated with malware or adversaries attempting to execute payloads from temporary or user-writable directories.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
3031
Detects the execution traces of the WizardUpdate malware, a macOS trojan that attempts to infiltrate macOS machines to steal data and is associated with other types of malicious payloads. The rule specifically looks for shell commands executing `curl` with a specific pattern (`=$(curl ` and `eval`) or `curl` commands containing `_intermediate_agent_`.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
0029
Detects a bash process initiating an outbound network connection to a remote IP address, which is a common indicator of a reverse shell. This rule specifically looks for '/bin/bash' processes making network connections, excluding connections to localhost or unspecified addresses.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
1028
Detects the execution of the Bash shell with the '-i' flag, which indicates an interactive shell. This is commonly used in reverse shells or other scenarios where an attacker wants to interact with the compromised system.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
0028
This rule detects the execution of the `nohup` command on Linux systems. `nohup` is a utility that allows a command to continue running in the background even after the user logs out or the terminal is closed. Attackers may leverage `nohup` to maintain persistence for malicious processes or to bypass restrictions in certain environments.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
0028
This rule detects the execution of the `bpftrace` utility with the `--unsafe` option. The `bpftrace` tool is a high-level tracing language for Linux, and the `--unsafe` option allows it to perform operations that could potentially compromise system stability or security, such as writing to arbitrary memory locations or executing arbitrary code in the kernel. This usage could indicate an attempt to perform advanced system manipulation, potentially for privilege escalation, stealthy execution, or system compromise.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
2026
Detects the execution of PHP CLI with the "-r" flag to run inline PHP code, specifically looking for calls to the "fsockopen" function. This combination is often used by attackers to create sockets for reverse shell connections, potentially in conjunction with functions like "exec" or "fopen". The rule also checks for common Unix shell names in the command line, indicating an attempt to spawn a shell.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
2025
Detects execution of the perl binary with the "-e" flag and common strings related to potential reverse shell activity. This rule looks for specific patterns in the command line arguments that indicate an attempt to establish a reverse shell using Perl's networking capabilities.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
2024
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