Detections

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

6,208 detections

This rule detects PowerShell script blocks that utilize .NET's SslStream for establishing encrypted network connections. Specifically, it looks for the use of 'System.Net.Security.SslStream', 'Net.Security.RemoteCertificateValidationCallback', and '.AuthenticateAsClient' which are indicative of a client-side SSL/TLS connection being programmatically established, potentially for command and control (C2) purposes to evade detection.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
1042
This rule detects RDP traffic communicating with the loopback address (127.0.0.1 or ::1) on either the source or destination port 3389, specifically looking for Windows Filtering Platform (WFP) events (EventID 5156). This behavior is indicative of RDP over a reverse SSH tunnel, where RDP traffic is redirected locally to bypass network restrictions or for covert communication. The rule explicitly filters out events originating from 'AppContainer Loopback' and known Thor processes to reduce false positives.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
0041
This rule detects attempts to execute common Windows operating system commands via HTTP GET requests, which is a common characteristic of web shell activity. The rule specifically looks for URL-encoded versions of commands like 'whoami', 'net user', 'cmd /c', 'powershell', 'tasklist', 'wmic', 'ssh', 'python', 'ipconfig', 'wget', 'curl', 'certutil', 'copy \\', 'dsquery', and 'nltest'. These commands are often used by attackers to gain information about the compromised system, escalate privileges, or establish further persistence after deploying a web shell.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
1040
Detects the execution of Netcat (nc.exe, ncat.exe, netcat.exe) with suspicious command-line arguments often associated with establishing listener modes, reverse shells, or proxy connections. Netcat is a versatile networking utility that can be used by adversaries for command and control (C2) communication, data exfiltration, or creating backdoors, often leveraging non-application layer protocols.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
1038
Detects a network connection initiated from a process located in the "C:\Users\Public" folder. Attackers are known to drop their malicious payloads and malware in this directory as it's writable by everyone. This rule helps hunt for potential suspicious or uncommon activity in the environment.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
0037
Detects suspicious DNS queries that contain a base64 encoded string, indicated by the '==.' pattern. This pattern is often used in DNS exfiltration techniques where data is encoded in base64 and sent via DNS queries to bypass network defenses.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
0037
Detects attempts to decode a base64 encoded Gzip archive within a PowerShell script. This technique is often used by adversaries to load malicious content into memory, leveraging standard encoding for obfuscation and memory-resident execution.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
0037
Detects the execution of the 'curl' command on Linux systems. This typically indicates an attempt to download files from a remote location or make web requests to external servers. This activity can be associated with adversaries transferring tools or communicating with command and control infrastructure.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
1036
This rule detects suspicious DNS queries specifically targeting 'api.telegram.org'. This domain is used by Telegram Bot API, which can be leveraged by various types of malware (e.g., RATs, ransomware) for command and control (C2) or data exfiltration. Monitoring these queries helps identify systems potentially communicating with malicious Telegram bots.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
3036
This rule detects when the Notepad++ updater utility (GUP.exe) is executed by a process other than Notepad++ itself, specifically when command-line arguments indicate a file download operation (containing '-unzipTo' and 'http'). This behavior can be indicative of an adversary abusing a legitimate application's updater for ingress tool transfer or other malicious file downloads, bypassing typical security controls that might monitor direct download utilities.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
0036
Detects potential Command and Control (C2) communication associated with the Small Sieve malware. This rule specifically looks for HTTP GET requests to 'api.telegram.org' with a specific chat_id and 'text=com/' in the URI, which are indicators of Small Sieve's use of the Telegram Bot API for C2.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
0034
This rule detects suspicious DNS queries that are characteristic of Cobalt Strike beacons. Specifically, it looks for DNS query names starting with 'aaa.stage.' or 'post.1', or containing '.stage.123456.'. These patterns are known indicators of Cobalt Strike's DNS communication for staging or command and control.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
0034
This rule detects the execution of the Tor client or Tor Browser, which are used to connect to the Tor anonymity network. Specifically, it looks for process creation events where the image path ends with '\tor.exe' or '\Tor Browser\Browser\firefox.exe'. This indicates an attempt to establish an anonymous connection, potentially for malicious command and control, data exfiltration, or to bypass network restrictions.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
1034
This rule detects HTTP POST requests that exhibit characteristics commonly associated with the Empire post-exploitation framework. Specifically, it looks for a combination of a distinct user-agent string ('Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko') and specific URI paths ('/admin/get.php', '/news.php', '/login/process.php'). This pattern is indicative of an Empire agent communicating with its command and control server.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
4033
This rule detects Cobalt Strike Malleable C2 profile patterns by analyzing HTTP proxy logs. It looks for specific User-Agent strings, HTTP methods (GET/POST), URIs, and hostnames that are characteristic of known Cobalt Strike profiles, including those mimicking Amazon, generic browsers, OCSP, and OneDrive traffic. The rule aims to identify command and control communications attempting to blend in with legitimate web traffic.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
1033
Detects suspicious User-Agent strings that appear to be Base64 encoded. This pattern has been observed in some malware, such as YamaBot, to obfuscate the true User-Agent. The rule specifically looks for Base64 encoded prefixes of common browser User-Agents like 'Chrome', 'AppleWebKit', 'Dalvik', and 'Mozilla', with an offset to account for potential padding variations.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
1033
Detects svchost.exe initiating an outbound network connection on TCP port 3389 (RDP) to a loopback address (127.0.0.0/8 or ::1/128). This behavior is indicative of RDP traffic being tunneled, potentially via a reverse SSH tunnel, to bypass network restrictions or for covert remote access.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
0033
Detects a potential exploitation attempt of CVE-2023-25157, a SQL injection vulnerability in GeoServer. The rule looks for specific GET requests to '/geoserver/ows' containing 'CQL_FILTER=' along with known vulnerable functions or SQL injection keywords in the query string.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
0031
Detects the execution of suspicious child processes from macOS installer package parent processes. This includes various scripting interpreters like osascript, JXA, and common network utilities like curl and wget, which can be abused during preinstall or postinstall phases of a package installation.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
0031
This rule detects suspicious user agent strings commonly associated with cryptocurrency miners (XMRig and CCMiner) in proxy logs. The presence of these user agents indicates that a system on the network might be infected with mining malware and is attempting to communicate with mining pools or command and control servers.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
1031
Detects attempts of decoding a base64 Gzip archive via PowerShell. This technique is often used as a method to load malicious content into memory afterward. The detection relies on the presence of 'FromBase64String' for decoding, 'MemoryStream' for in-memory operations, and 'H4sI' which is a common magic string for Gzip compressed data.
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SigmaHQ Detections@sigmaHQ
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SigmaHQ
2 years ago
0031
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