This rule detects potential initial access activity where an adversary uploads a web shell or malicious script to a web server via a file upload mechanism (e.g., through a web form using multipart/form-data), followed by a GET or POST request to access the uploaded file. By checking the body content of HTTP requests for file upload indicators such as "Content-Disposition: form-data" and "filename=", the rule identifies suspicious upload activities. This sequence of actions is commonly used by attackers to gain and maintain access to compromised web servers.

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Identifies suspicious files being written by the Microsoft Exchange Server Unified Messaging (UM) service. This activity has been observed exploiting CVE-2021-26858.

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Identifies suspicious processes being spawned by the Microsoft Exchange Server worker process (w3wp). This activity may indicate exploitation activity or access to an existing web shell backdoor.

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Detects the creation of a PHP file in the WordPress plugin directory, which is a common technique used by attackers to establish persistence on a compromised web server. Attackers may upload a malicious PHP file and call it from a web browser to gain remote access to the server.

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Identifies the creation of ASPX/ASHX/ASMX files in specific directories that are commonly targeted by attackers to deploy web shells.

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Identifies suspicious processes spawned from the SAP NetWeaver application. This may indicate an attempt to execute commands via webshell.

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Identifies suspicious Java file creation in the IRJ directory of the SAP NetWeaver application. This may indicate an attempt to deploy a webshell.

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Identifies successful exploitation of CVE-2023-50164, a critical path traversal vulnerability in Apache Struts 2 file upload functionality. This high-fidelity rule detects a specific attack sequence where a malicious multipart/form-data POST request with WebKitFormBoundary is made to a Struts .action upload endpoint, immediately followed by the creation of a JSP web shell file by a Java process in Tomcat's webapps directories. This correlated activity indicates active exploitation resulting in remote code execution capability through unauthorized file upload and web shell deployment.

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Identifies suspicious processes being spawned by the ScreenConnect server process (ScreenConnect.Service.exe). This activity may indicate exploitation activity or access to an existing web shell backdoor.

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This rule detects connections accepted by a simple HTTP web server in Python and PHP built-in modules. Adversaries may create simple HTTP web servers to establish persistence on a compromised system by uploading a reverse or command shell payload to the server web root, allowing them to regain remote access to the system if lost. This event may occur when an attacker requests the server to execute a command or script via a potential backdoor.

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This rule detects the creation of a simple HTTP web server using PHP or Python built-in modules. Adversaries may create simple HTTP web servers to establish persistence on a compromised system by uploading a reverse or command shell payload to the server web root, allowing them to regain remote access to the system if lost.

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Identifies suspicious child processes executed via a web server, which may suggest a vulnerability and remote shell access. Attackers may exploit a vulnerability in a web application to execute commands via a web server, or place a backdoor file that can be abused to gain code execution as a mechanism for persistence.

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Identifies suspicious command executions via a web server, which may suggest a vulnerability and remote shell access. Attackers may exploit a vulnerability in a web application to execute commands via a web server, or place a backdoor file that can be abused to gain code execution as a mechanism for persistence.

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This rule leverages the "new_terms" rule type to detect unusual child process executions originating from web server processes on Linux systems. Attackers may exploit web servers to maintain persistence on a compromised system, often resulting in atypical child process executions. As child process spawns from web server parent processes are common, the "new_terms" rule type approach helps identify deviations from normal behavior.

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This rule leverages the "new_terms" rule type to detect unusual command executions originating from web server processes on Linux systems. Attackers may exploit web servers to maintain persistence on a compromised system, often resulting in atypical command executions. As command execution from web server parent processes is common, the "new_terms" rule type approach helps to identify deviations from normal behavior.

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This rule leverages the "new_terms" rule type to detect unusual file creations originating from web server processes on Linux systems. Attackers may exploit web servers to maintain persistence on a compromised system, often resulting in atypical file creations. As file creations from web server processes are common, the "new_terms" rule type approach helps to identify deviations from normal behavior.

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This rule detects the exploitation of a web server through the execution of a suspicious process by common web server user accounts. Attackers may upload a web shell to a web server to maintain access to the system.

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This rule detects potential command injection attempts via web server requests by identifying URLs that contain suspicious patterns commonly associated with command execution payloads. Attackers may exploit vulnerabilities in web applications to inject and execute arbitrary commands on the server, often using interpreters like Python, Perl, Ruby, PHP, or shell commands. By monitoring for these indicators in web traffic, security teams can identify and respond to potential threats early.

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Identifies suspicious commands executed via a web server, which may suggest a vulnerability and remote shell access.

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Identifies suspicious processes being spawned by the Windows Server Update Service. This activity may indicate exploitation activity or access to an existing web shell backdoor.

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