Attackers Deploy Web Shells via RCE Vulnerabilities to Maintain Persistence on Web Servers
What Happened — Threat researchers observed a surge in web‑shell deployments that leverage arbitrary‑file‑write and remote‑code‑execution (RCE) flaws. Attackers drop tiny scripts, often named to blend with legitimate files, and sometimes embed default back‑door credentials.
Why It Matters for TPRM —
- Web shells provide a stealthy foothold, enabling lateral movement and data exfiltration from third‑party web assets.
- Persistent malicious code can evade standard vulnerability scans if the shell’s filename mimics benign resources.
- Compromised vendor portals become a conduit for downstream supply‑chain attacks on your organization’s ecosystem.
Who Is Affected — All industries that rely on externally hosted web applications, including SaaS providers, cloud‑hosted services, e‑commerce sites, and any organization exposing public‑facing web servers.
Recommended Actions —
- Review all third‑party web‑hosting contracts for mandatory secure‑coding and patch‑management clauses.
- Validate that vendors employ continuous file‑integrity monitoring and block unauthorized file uploads.
- Conduct regular penetration tests focused on arbitrary‑file‑write and RCE vectors.
Technical Notes — Attackers exploit CVE‑2024‑XXXX (arbitrary file write) and CVE‑2024‑YYYY (RCE) to plant PHP, ASP, or JSP web shells. The shells often contain hard‑coded credentials (e.g., admin:password) and are executed via HTTP requests. Persistence is achieved by configuring the shell to run on server start‑up or via scheduled tasks. Source: SANS Internet Storm Center