Citrix NetScaler ADC & Gateway Flaw Lets Attackers Obtain Sensitive Data Remotely

A security vulnerability has been identified in Citrix NetScaler ADC and Gateway appliances, allowing remote attackers to access sensitive data without authentication.

This flaw, identified as an out-of-bounds memory read issue, affects versions up to 13.1-50.23 of the software and has been compared to the previously known CitrixBleed vulnerability, though it is considered less severe in terms of the sensitivity of the data exposed, reads advisory from Bishop Fox.

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The vulnerability impacts explicitly NetScaler appliances configured as a Gateway or for Authentication, Authorization, and Auditing (AAA) services.

These configurations are commonly used in enterprise environments to manage secure remote access and traffic management.

The flaw allows attackers to exploit the system by sending specially crafted requests to the vulnerable interface, potentially leaking information such as credentials and session tokens in HTTP request bodies.

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The issue stems from improper handling of the HTTP Host request header within the software’s web interface.

When handling overly long header values, the software incorrectly calculates string lengths, leading to memory mismanagement and the unintended disclosure of data stored in memory.

“Bishop Fox staff determined that NetScaler ADC and Gateway products were vulnerable to an unauthenticated out-of-bounds memory read and exploited the vulnerability to capture sensitive information from the appliance’s process memory, including HTTP request bodies”. 

Citrix has acknowledged the vulnerability and released updates to mitigate the issue. Versions 13.1-51.15 and later contain fixes that address this security flaw.

Citrix strongly advises all users of affected versions to update their systems immediately to prevent potential exploitation, as active exploits of this vulnerability have been observed in the wild.

This vulnerability highlights the ongoing challenges in securing network appliances against sophisticated cyber threats.

Users of Citrix NetScaler ADC and Gateway are urged to review their systems and apply the necessary updates without delay to safeguard their networks against potential data breaches and unauthorized access.

For organizations using older, now end-of-life software versions, upgrading to a supported version is crucial not only to address this specific vulnerability but also to ensure overall system security and compliance with current standards.

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