CVE-2017-5933 : Security Advisory and Response

Citrix NetScaler ADC and NetScaler Gateway versions 10.5, 11.0, and 11.1 have a vulnerability related to GCM nonces that could potentially be exploited by attackers.

Understanding CVE-2017-5933

This CVE involves a vulnerability in Citrix NetScaler ADC and NetScaler Gateway versions 10.5, 11.0, and 11.1 that could allow attackers to acquire the GCM authentication key.

What is CVE-2017-5933?

The vulnerability in Citrix NetScaler ADC and NetScaler Gateway versions 10.5, 11.0, and 11.1 involves the random generation of GCM nonces, potentially making it easier for attackers to obtain the GCM authentication key and deceive the system by exploiting a reused nonce in a session.

The Impact of CVE-2017-5933

This vulnerability could lead to a security breach where attackers could spoof data and potentially perform a "forbidden attack" due to the reuse of nonces in a session.

Technical Details of CVE-2017-5933

Citrix NetScaler ADC and NetScaler Gateway versions 10.5, 11.0, and 11.1 are affected by this vulnerability.

Vulnerability Description

The vulnerability arises from the random generation of GCM nonces, making it marginally easier for remote attackers to obtain the GCM authentication key and spoof data by leveraging a reused nonce in a session.

Affected Systems and Versions

Citrix NetScaler ADC version 10.5 before Build 65.11
Citrix NetScaler ADC version 11.0 before Build 69.12/69.123
Citrix NetScaler ADC version 11.1 before Build 51.21

Exploitation Mechanism

Attackers can exploit this vulnerability by acquiring the GCM authentication key and deceiving the system through the reuse of nonces in a session.

Mitigation and Prevention

It is crucial to take immediate steps to address and prevent the exploitation of this vulnerability.

Immediate Steps to Take

Update Citrix NetScaler ADC and NetScaler Gateway to the recommended builds to mitigate the vulnerability.
Monitor network traffic for any suspicious activity that could indicate exploitation of the vulnerability.

Long-Term Security Practices

Implement strong encryption protocols and regularly update security measures to prevent similar vulnerabilities.
Conduct regular security audits and penetration testing to identify and address any potential security gaps.

Patching and Updates

Apply patches provided by Citrix to fix the vulnerability and enhance the security of the affected systems.