CVE-2017-15906 Explained : Impact and Mitigation

CVE-2017-15906 involves attackers being able to create files with zero length due to a vulnerability in OpenSSH versions prior to 7.6. Learn about the impact, technical details, and mitigation steps.

Understanding CVE-2017-15906

This CVE identifier highlights a security issue in OpenSSH versions before 7.6 that allows attackers to create empty files by bypassing readonly mode restrictions.

What is CVE-2017-15906?

The vulnerability in the process_open function in sftp-server.c in OpenSSH versions prior to 7.6 enables malicious actors to perform write operations in readonly mode, leading to the creation of files with zero length.

The Impact of CVE-2017-15906

This vulnerability can be exploited by attackers to manipulate files and potentially disrupt system integrity and confidentiality. It poses a risk to the security of systems using affected OpenSSH versions.

Technical Details of CVE-2017-15906

Vulnerability Description

The issue arises from a lack of proper restrictions in the process_open function of sftp-server.c, allowing unauthorized write operations in readonly mode.

Affected Systems and Versions

Vendor: n/a
Product: n/a
Versions: All versions prior to OpenSSH 7.6

Exploitation Mechanism

Attackers can exploit this vulnerability to create files with zero length by circumventing the intended readonly mode restrictions in OpenSSH versions before 7.6.

Mitigation and Prevention

Immediate Steps to Take

Update OpenSSH to version 7.6 or newer to mitigate the vulnerability.
Monitor file creation activities for suspicious behavior.

Long-Term Security Practices

Implement least privilege access controls to limit write permissions.
Regularly review and update security configurations to address emerging threats.

Patching and Updates

Apply security patches provided by OpenSSH to address the vulnerability and enhance system security.