Detections
Explore public detection logic contributed by the community across SIEM and rule languages.
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Detects file modification or creation events affecting critical authentication components, specifically Pluggable Authentication Modules (pam_unix.so) and OpenSSH binaries (sshd, ssh, scp). Such activity is highly indicative of an attempt to backdoor the authentication process to facilitate unauthorized access or credential theft, as observed in Operation Highland.
Detects the modification or creation of shared object files (.so) within common Linux Pluggable Authentication Modules (PAM) directories. Adversaries often modify these modules to establish persistence, capture credentials, or create backdoors for authentication bypass.
This rule detects modifications to Nginx configuration files (nginx.conf, or files within conf.d, sites-enabled, or sites-available directories) by processes other than authorized system management tools (e.g., nginx, apt, ansible). It further correlates these file modifications with subsequent Nginx configuration reloads, which is a common behavior when an adversary attempts to apply malicious configuration changes to a web server.
This rule monitors for signs of Atlas RAT activity on Linux systems, including the execution of processes matching known Atlas RAT naming conventions, unauthorized modifications to system persistence mechanisms (systemd or init.d directories) by non-package management utilities, and anomalous outbound network connections originating from sshd or PAM-related processes.
This rule detects unauthorized modifications or creations of files within critical Linux Pluggable Authentication Module (PAM) directories (such as /etc/pam.d/ and /lib/security/). Attackers often target these files to implement backdoors, bypass authentication mechanisms, or harvest credentials. The rule excludes common package management tools to minimize false positives.
Detects suspicious behavior involving the 'uptime' system utility, including execution from non-standard paths, unexpected outbound network connections, spawning child processes, or replacement of the legitimate /usr/bin/uptime binary. These behaviors are indicative of masquerading or binary hijacking.
This rule monitors Linux authentication logs for anomalies related to Pluggable Authentication Modules (PAM). It identifies potential security risks by detecting file operations (read, write, create) within PAM-related processes, references to world-writable or temporary directories that may be used for staging credentials, and unusual authentication event patterns.
Detects instances of the 'smbd' process executing from non-standard locations or initiating network connections on ports other than the default SMB ports (139, 445), which may indicate a rogue service, masquerading, or network pivoting activity.
Detects the execution of known GSocket/GS-Netcat tools or the usage of the 'uptime' command when accompanied by network activity, which may indicate process masquerading.
This rule detects potential persistence mechanisms on Linux systems by identifying the creation of new systemd service files, modifications to init.d scripts, or the use of systemctl to enable or start services. The rule specifically excludes standard package management activities (apt, yum, dnf, dpkg) and flags if the triggered service operation involves suspicious file paths.
This rule detects unauthorized write, modification, or creation events on critical SSH binary files (sshd, ssh, scp) on Linux systems. It excludes legitimate package management tools (e.g., apt, yum, dpkg, rpm) from triggering alerts to reduce noise from system updates.
This rule monitors for modifications to critical Name Service Switch (NSS) configuration files (/etc/nsswitch.conf) or the creation/loading of NSS shared library files (/lib/libnss_*.so). Adversaries may target these files to manipulate identity management, gain persistence, or escalate privileges by intercepting authentication requests.
Detects suspicious activity involving the uptime utility on Linux systems. This includes execution from non-standard paths, invocation with unexpected command-line arguments, execution with unusual parent processes, or evidence of the uptime binary being overwritten or written to a non-standard location. Such behavior is often indicative of masquerading or attempts to hide malicious activities.
Detects the deployment and execution of GS-Netcat (gsocket), a tool often used for creating persistent reverse shells or backdoors. The rule identifies processes associated with gsocket, instances where the 'uptime' command is masqueraded with suspicious command-line arguments, and unauthorized creation or modification of systemd service files designed for persistence.
Detects potential credential harvesting activities targeting the SSH and PAM authentication stacks. The rule identifies suspicious file operations (creation/modification/read) by authentication-related processes (sshd, login, su, sudo) involving sensitive files like /etc/shadow or non-standard file paths in temporary directories, as well as the spawning of interpreters that write to these suspicious locations.
Detects two suspicious behaviors related to OpenSSH. The first scenario identifies unauthorized modifications, creations, or renames of core OpenSSH binaries (/usr/sbin/sshd, /usr/bin/ssh, /usr/bin/scp) that are not initiated by common package managers, which could indicate persistence mechanisms or backdooring. The second scenario monitors ssh/sshd/scp processes creating or modifying files in common temporary or world-writable directories (/tmp, /var/tmp, /dev/shm, etc.), which is often indicative of credential harvesting or data staging.
This rule detects low-frequency, external network connections originating from Linux processes that are either explicitly known to be associated with malicious tools (e.g., gs-netcat, gsocket, atlasd) or are masquerading as legitimate system utilities (e.g., uptime, smbd) in a manner consistent with the Velvet Ant Operation Highland activity. The detection aggregates connections by process metadata and flags low-frequency outbound traffic, which is indicative of C2 beaconing.
This rule detects potentially malicious or masqueraded Samba (smbd) activity on Linux systems. It monitors for three conditions: smbd processes launched from non-standard binary paths, smbd process network activity from non-standard binary paths, and smbd processes spawned by unauthorized or unexpected parent processes. These patterns are often associated with unauthorized SMB service deployment, malware persistence, or masquerading techniques.
Detects potential tampering with Pluggable Authentication Modules (PAM) or configuration files on Linux systems. This includes the loading of non-standard shared libraries by authentication-related processes (sshd, sudo, login), modification of core PAM modules (e.g., pam_unix.so) by non-package manager processes, and unauthorized modifications to files within /etc/pam.d/. It also monitors for credential-related activity where authentication processes write data into temporary or hidden directories.
Detects Linux processes running from non-standard directories that exhibit network beaconing behavior, correlated with the concurrent creation or modification of systemd unit files on the same host. This pattern is indicative of a remote access trojan (RAT) or backdoor establishing persistent command-and-control.
Detects signs of JDY botnet activity on Linux systems, specifically identifying shell-based payload downloads using curl or wget, or the execution of binaries directly from temporary directories, a pattern common in IoT firmware compromises.
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