Perl Backdoor BkDService

The BkDService is a backdoor written in Perl that connects to and communicates with attacker C2 over IRC. BkDService was used as the payload in an attack against a Drupal CMS that is vulnerable to CVE-2018-7600. The backdoor has functionality that includes the execution of shell commands, the download of files, a TCP connect port scanner, and the ability to take part in UDP DDoS attacks.

Exploitation

Stages

1. The compromised server attempts to join an IRC channel on the attacker C2 server.
2. The attacker C2 sends commands over IRC as private messages.
3. The compromised server replies over IRC confirming that functionality was successfully invoked.

Prerequisites

The attacker must be able to inject the malicious code onto the web server through another vulnerability or exploit.

Alert Logic Coverage

Alert Logic® has evaluated its customer base for exposure to the exploit and has developed signatures for mitigating the threat depending on the security service in place.

The Network-Based Intrusion Detection System (IDS) has been updated with the new signatures for this exploit when detected via Alert Logic Threat Manager™. If this signature is detected, an incident is generated in the Alert Logic console.

Recommendations for Mitigation

Ensure that all public internet-facing hosts have available patches applied and are sufficiently hardened for public access.