CVE-2018-11347 in YunoHost
Summary
by MITRE
The YunoHost 2.7.2 through 2.7.14 web application is affected by one HTTP Response Header Injection. This flaw allows an attacker to inject, into the response from the server, one or several HTTP Header. It requires an interaction with the user to send him the malicious link. It could be used to perform other attacks such as user redirection to a malicious website, HTTP response splitting, or HTTP cache poisoning.
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Analysis
by VulDB Data Team • 04/17/2020
The vulnerability CVE-2018-11347 represents a critical HTTP Response Header Injection flaw in the YunoHost web application platform, affecting versions 2.7.2 through 2.7.14. This security weakness stems from inadequate input validation and sanitization within the application's response handling mechanisms, allowing malicious actors to inject arbitrary HTTP headers into server responses. The vulnerability operates by exploiting insufficient sanitization of user-supplied input that flows into HTTP response headers without proper encoding or validation, creating a pathway for attackers to manipulate the HTTP communication between client and server. The flaw specifically impacts the application's ability to properly escape or validate data that gets embedded into HTTP headers, making it susceptible to header injection attacks that can fundamentally alter how web browsers and intermediaries process the responses.
The technical execution of this vulnerability requires an attacker to craft malicious links that, when clicked by a user, trigger the injection of crafted HTTP headers into the server's response. This user interaction requirement makes the attack vector more complex but not impossible to exploit, as social engineering becomes a necessary component for successful exploitation. When successfully exploited, the header injection can enable several dangerous attack scenarios including user redirection to malicious websites through Location header manipulation, HTTP response splitting attacks that can confuse web proxies and caches, and HTTP cache poisoning that can affect multiple users. The vulnerability's impact extends beyond simple redirection as it can compromise the integrity of HTTP communications and potentially enable more sophisticated attacks such as cross-site scripting through malicious header injection or session manipulation via Set-Cookie header tampering.
From a cybersecurity perspective, this vulnerability aligns with CWE-113, which specifically addresses "Improper Neutralization of CRLF Characters in HTTP Headers" and represents a classic example of HTTP header injection vulnerabilities that have been documented in various web application security frameworks. The attack pattern follows established methodologies described in the MITRE ATT&CK framework under the technique of "T1566 - Phishing" where initial access is gained through malicious links, and potentially extends to "T1071.004 - Application Layer Protocol: DNS" and "T1562.001 - Impair Defenses: Disable or Modify Tools" through the potential for cache poisoning attacks that can disrupt normal application behavior. The vulnerability's exploitation demonstrates the critical importance of proper input validation and output encoding in web applications, particularly in frameworks that handle user-generated content or dynamic response construction, as it can effectively bypass security controls that rely on predictable HTTP header behavior.
The operational impact of this vulnerability extends beyond immediate exploitation as it can create persistent security risks for affected organizations using YunoHost platforms. Once exploited, the header injection can enable attackers to manipulate user sessions, redirect traffic to malicious infrastructure, or poison application caches in ways that persist beyond individual attack sessions. Organizations may face significant reputational damage if users are redirected to phishing sites or if the vulnerability is used to compromise user credentials through session hijacking. The vulnerability also highlights the importance of maintaining up-to-date security patches, as this flaw existed across multiple minor versions of the YunoHost platform, indicating a potential gap in the application's security testing and validation processes. Additionally, the requirement for user interaction suggests that this vulnerability could be particularly challenging to detect and prevent through automated security scanning alone, requiring a combination of user education, network monitoring, and proper application security controls to mitigate effectively. The vulnerability serves as a reminder of the critical need for robust input validation and output encoding practices in web applications, particularly in platforms that serve as infrastructure for user services and email hosting, where the compromise of one component can affect numerous end users and their data.