CVE-2019-6111 Explained : Impact and Mitigation

OpenSSH 7.9 SCP Implementation Vulnerability

Understanding CVE-2019-6111

What is CVE-2019-6111?

The CVE-2019-6111 vulnerability is found in OpenSSH 7.9, affecting the scp implementation. It allows a malicious server or a Man-in-The-Middle attacker to replace files in the target directory of the scp client, potentially leading to unauthorized access.

The Impact of CVE-2019-6111

This vulnerability can be exploited by attackers to manipulate files and directories, including critical files like .ssh/authorized_keys, compromising the integrity and security of the system.

Technical Details of CVE-2019-6111

Vulnerability Description

The scp client in OpenSSH 7.9 only performs basic validation of received object names, enabling malicious servers to send arbitrary files to the client, leading to potential file manipulation.

Affected Systems and Versions

Vendor: n/a
Product: n/a
Versions: All versions are affected

Exploitation Mechanism

Malicious scp server or Man-in-The-Middle attacker can replace files in the target directory
Recursive operation (-r) can manipulate subdirectories

Mitigation and Prevention

Immediate Steps to Take

Update OpenSSH to a patched version
Avoid using scp with untrusted servers
Monitor system logs for any suspicious activities

Long-Term Security Practices

Implement secure file transfer protocols like SFTP
Regularly review and update security configurations

Patching and Updates

Apply patches provided by OpenSSH to fix the vulnerability