A Server-Side Request Forgery (SSRF) vulnerability in Cowrie's emulated shell mode allows unauthenticated attackers to abuse the honeypot as an amplification vector for HTTP-based denial-of-service attacks against arbitrary third-party hosts.
When Cowrie operates in emulated shell mode (the default configuration), it basically emulates common Linux commands. The wget and curl command emulations actually perform real outbound HTTP requests to the destinations specified by the attacker, as this functionality is intended to allow Cowrie to save downloaded files for later inspection.
An attacker who connects to the honeypot via SSH or Telnet can repeatedly invoke these commands targeting a victim host. Since there was no rate limiting mechanism in place, the attacker could generate unlimited outbound HTTP traffic toward the victim. The requests originate from the honeypot's IP address, effectively masking the attacker's identity and turning the honeypot into an unwitting participant in distributed denial-of-service (DDoS) attacks.
This vulnerability was observed being actively exploited in the wild.
Acknowledgements This vulnerability was investigated by Abraham Gebrehiwot and Filippo Lauria, with additional contributions from Michele Castellaneta, Claudio Porta and Sara Afzal. All researchers are affiliated with the Institute of Informatics and Telematics (IIT), Italian National Research Council (CNR).
Fix
This issue has been fixed in version 2.9.0 via PR #2800, which introduces a rate limiting mechanism for outbound requests in command emulations such as wget and curl.
This is a rudimentary proof of concept demonstrating the amplification potential of this vulnerability.
Setup:
2.9.0Exploitability
AV:NAC:LAT:NPR:NUI:NVulnerable System
VC:NVI:NVA:LSubsequent System
SC:NSI:NSA:L6.9/CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L