CVE-2018-17938 in Zimbra Collaboration
Summary
by MITRE
Zimbra Collaboration before 8.8.10 GA allows text content spoofing via a loginErrorCode value.
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Analysis
by VulDB Data Team • 03/29/2020
The vulnerability identified as CVE-2018-17938 affects Zimbra Collaboration software versions prior to 8.8.10 GA, representing a text content spoofing issue that can be exploited to manipulate user-facing error messages during authentication processes. This flaw specifically involves the loginErrorCode value which is used to communicate authentication failures to users. The vulnerability stems from insufficient input validation and output encoding mechanisms within the Zimbra web interface, allowing malicious actors to inject crafted text content that gets displayed to users in error message contexts. Such spoofing attacks can be particularly dangerous in security-sensitive environments where users rely on accurate error messages to identify legitimate authentication issues versus potential attacks.
The technical implementation of this vulnerability occurs when the Zimbra application processes authentication requests and generates error responses containing the loginErrorCode value. When this value contains unescaped or improperly sanitized user-controllable input, it becomes susceptible to content injection attacks. Attackers can manipulate the loginErrorCode parameter to display misleading information to users, potentially causing confusion about authentication status or redirecting users to malicious content. This issue falls under CWE-79 - Cross-Site Scripting and CWE-116 - Improper Encoding or Escaping of Output, both of which are fundamental web application security weaknesses that can lead to various downstream attacks including phishing and social engineering operations.
The operational impact of CVE-2018-17938 extends beyond simple message manipulation to potentially enable more sophisticated attack vectors. Users encountering spoofed error messages may be misled into believing they are experiencing legitimate authentication problems when they are actually being targeted by an attack. This can result in users inadvertently following malicious links or providing additional credentials to attackers who exploit the spoofed error messages to gain trust and access to legitimate accounts. The vulnerability also impacts the integrity of the authentication system by undermining user confidence in the application's error reporting mechanisms and potentially enabling credential harvesting attacks that leverage the confusion caused by misleading error messages.
Security practitioners should implement immediate mitigations including upgrading to Zimbra Collaboration 8.8.10 GA or later versions that contain the necessary patches to address the text content spoofing vulnerability. Organizations should also review their web application security configurations to ensure proper input validation and output encoding mechanisms are in place for all user-controllable parameters. The remediation process should include comprehensive testing of error message handling components and monitoring for potential exploitation attempts. Additionally, implementing web application firewalls and content security policies can provide additional layers of protection against similar vulnerabilities. This issue aligns with ATT&CK technique T1566 - Phishing and T1078 - Valid Accounts, as it can facilitate both social engineering attacks and unauthorized access attempts through manipulation of authentication feedback mechanisms.