{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata. Fed continuously.","feed_url":"https://feed.craftedsignal.io/products/apache/feed.json","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cpes":[],"_cs_cves":[],"_cs_exploited":false,"_cs_has_poc":false,"_cs_poc_references":[],"_cs_products":["Elastic Defend","Apache","Nginx"],"_cs_severities":["low"],"_cs_tags":["web-shell","command-execution","persistence","linux"],"_cs_type":"advisory","_cs_vendors":["Elastic","Apache","Nginx"],"content_html":"\u003cp\u003eThis detection rule identifies unusual command execution originating from web server parent processes on Linux hosts, a common tactic used in web shell attacks. Adversaries exploit vulnerabilities in web servers such as Apache and Nginx to execute arbitrary commands, blending malicious activity with legitimate server processes. The rule focuses on identifying unusual patterns and contexts, such as unexpected working directories or command structures, to flag potential compromises. This technique allows attackers to maintain persistence, execute commands, and potentially establish command and control within the compromised system. The rule is designed to detect such activities by monitoring process execution events and comparing them against a baseline of normal web server behavior.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eAn attacker exploits a vulnerability in a web application running on a Linux server.\u003c/li\u003e\n\u003cli\u003eThe attacker gains initial access and uploads a web shell, a malicious script (e.g., PHP, Python) that allows remote command execution.\u003c/li\u003e\n\u003cli\u003eThe web server (e.g., Apache, Nginx) spawns a process to execute the web shell.\u003c/li\u003e\n\u003cli\u003eThe attacker uses the web shell to execute commands, such as spawning a reverse shell or listing files.\u003c/li\u003e\n\u003cli\u003eA shell process (e.g., bash, sh) is created as a child of the web server process.\u003c/li\u003e\n\u003cli\u003eThe attacker uses the shell to perform reconnaissance, such as identifying user accounts and network configurations.\u003c/li\u003e\n\u003cli\u003eThe attacker attempts to establish persistence by creating a cron job or modifying system files.\u003c/li\u003e\n\u003cli\u003eThe attacker uses the compromised server as a command and control node to communicate with other systems or exfiltrate data.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eA successful web shell attack can lead to complete compromise of the web server and potentially other systems on the network. Attackers can steal sensitive data, modify web pages, or use the server to launch further attacks. The impact can range from data breaches and defacement to denial-of-service attacks and lateral movement within the network. While this specific detection rule has low severity, failing to detect and remediate these attacks can have significant consequences.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eDeploy the Sigma rule \u003ccode\u003eDetect Unusual Shell Spawned by Web Server\u003c/code\u003e to your SIEM and tune for your environment to identify suspicious command execution from web server processes.\u003c/li\u003e\n\u003cli\u003eInvestigate alerts triggered by the \u003ccode\u003eDetect Web Server Child Process Executing Shell with Command Line Arguments\u003c/code\u003e Sigma rule to identify potentially compromised web servers.\u003c/li\u003e\n\u003cli\u003eReview the process command lines from the alerts and exclude specific working directories like /var/www/dev or /var/www/test from the rule to reduce false positives.\u003c/li\u003e\n\u003cli\u003eImplement additional monitoring and alerting for similar activities, focusing on unusual command executions and web server behavior as mentioned in the \u003ccode\u003eResponse and Remediation\u003c/code\u003e section of the rule documentation.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2026-06-01T15:44:23Z","date_published":"2026-06-01T15:44:23Z","id":"https://feed.craftedsignal.io/briefs/2026-06-web-server-command-execution/","summary":"This rule detects potential command execution from a web server parent process on a Linux host, indicating a possible web shell attack where adversaries exploit web server vulnerabilities to execute arbitrary commands.","title":"Unusual Command Execution from Web Server Parent Process on Linux","url":"https://feed.craftedsignal.io/briefs/2026-06-web-server-command-execution/"}],"language":"en","title":"CraftedSignal Threat Feed — Apache","version":"https://jsonfeed.org/version/1.1"}