Web Shell

A web shell is a malicious piece of code or script deployed on a compromised web server that grants an attacker remote control capabilities through a web interface. In the context of the "Deepening Control" phase and as a sub-technique of "Server Software Component" attacks, web shells represent a critical post-exploitation tool that allows adversaries to establish persistence, escalate privileges, and maintain covert access to the target environment. Once deployed, these shells can execute arbitrary commands with the same permissions as the web server process, provide file management capabilities, enable lateral movement within the network, and often include features to evade detection such as encryption, obfuscation, and password protection. Attackers typically inject web shells through vulnerabilities like file upload flaws, remote file inclusion, SQL injection, or direct access to web directories following successful server compromise. Unlike traditional remote access tools, web shells leverage standard web protocols (HTTP/HTTPS) for command and control communication, making them particularly difficult to detect as they blend with legitimate web traffic while providing attackers with a persistent foothold in the compromised environment.