CVE-2016-20011 in libgrss
Summary
by MITRE • 05/26/2021
libgrss through 0.7.0 fails to perform TLS certificate verification when downloading feeds, allowing remote attackers to manipulate the contents of feeds without detection. This occurs because of the default behavior of SoupSessionSync.
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Analysis
by VulDB Data Team • 05/29/2021
The vulnerability identified as CVE-2016-20011 affects the libgrss library version 0.7.0 and earlier, representing a critical security flaw in how the library handles secure communications when downloading RSS feeds. This issue stems from the library's failure to properly validate TLS certificates during the feed retrieval process, creating a significant attack surface that enables man-in-the-middle adversaries to intercept and manipulate feed content without detection. The root cause lies in the default configuration of SoupSessionSync, which is a component within the library responsible for handling HTTP requests and responses.
The technical implementation of this vulnerability demonstrates a fundamental flaw in the library's security architecture where certificate validation is either disabled or improperly configured during the SSL/TLS handshake process. When libgrss attempts to download feeds from remote servers, it establishes secure connections but fails to verify the authenticity of the server certificates presented. This behavior creates a trust relationship that can be easily exploited by attackers who position themselves between the client and the feed server, allowing them to perform certificate spoofing attacks. The vulnerability specifically impacts the cryptographic security controls that should normally validate the identity of the remote server and ensure data integrity during transmission.
From an operational perspective, this vulnerability poses severe risks to users who rely on RSS feeds for critical information updates, news aggregation, or automated content processing. Attackers could inject malicious content into feeds, redirect users to phishing sites, or disseminate false information through compromised feed sources. The impact extends beyond simple content manipulation as it undermines the trust model that RSS feeds rely upon for information integrity. This flaw particularly affects applications that aggregate content from multiple sources, as a single compromised feed could compromise the entire information ecosystem. The vulnerability also creates opportunities for advanced persistent threats to establish footholds through feed-based delivery mechanisms.
The security implications of this vulnerability align with CWE-295, which addresses improper certificate validation in security protocols, and relates to ATT&CK technique T1195.001 for content injection attacks. Organizations using affected versions of libgrss should immediately implement mitigations including updating to patched versions of the library, implementing additional validation layers, or configuring explicit certificate verification settings. The recommended approach involves enforcing strict certificate validation policies and ensuring that all network communications utilize properly configured SSL/TLS implementations. Additionally, implementing network monitoring to detect anomalous feed content patterns can provide early warning capabilities for potential exploitation attempts. Security teams should also consider deploying certificate pinning mechanisms where appropriate and establish regular vulnerability assessment procedures to identify similar configuration flaws in other network libraries and components.