CVE-2022-21692 in OnionShare
Summary
by MITRE • 01/19/2022
OnionShare is an open source tool that lets you securely and anonymously share files, host websites, and chat with friends using the Tor network. In affected versions anyone with access to the chat environment can write messages disguised as another chat participant.
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Analysis
by VulDB Data Team • 01/20/2022
The vulnerability identified as CVE-2022-21692 affects OnionShare, a widely used open source tool designed for secure and anonymous file sharing, website hosting, and instant messaging through the Tor network. This tool serves as a critical component in privacy-focused communications, particularly for journalists, activists, and researchers who require secure channels for information exchange. The vulnerability represents a significant flaw in the application's chat functionality that undermines the integrity of user communications and trust within the system.
The technical nature of this vulnerability lies in the improper validation and authentication mechanisms within the chat component of OnionShare. Specifically, the flaw allows any authenticated user within the chat environment to craft and transmit messages that appear to originate from other participants in the conversation. This represents a classic case of identity spoofing or impersonation, where the malicious actor can manipulate the message source field to disguise their communications as legitimate messages from trusted contacts. The vulnerability essentially breaks the authentication model that should prevent unauthorized message attribution, creating a scenario where the integrity of the chat environment is compromised.
From an operational impact perspective, this vulnerability creates serious security implications for users relying on OnionShare for confidential communications. An attacker who gains access to a chat session can manipulate the conversation flow by inserting misleading or malicious messages that appear to come from legitimate participants. This can lead to social engineering attacks where false information is disseminated within the chat environment, potentially causing confusion, misinformation, or even coordinated deception among users. The vulnerability undermines the fundamental trust model of the application, as users cannot reliably verify the authenticity of messages they receive, which directly impacts the security posture of sensitive communications.
The vulnerability aligns with CWE-352, which describes Cross-Site Request Forgery, and more specifically relates to CWE-287, which addresses improper authentication mechanisms. From an ATT&CK framework perspective, this vulnerability maps to technique T1566, which involves social engineering through manipulation of communication channels, and T1557, which covers credential access through manipulation of network communications. The attack surface is particularly concerning because it allows for persistent manipulation of chat conversations without requiring elevated privileges beyond basic access to the chat environment.
Mitigation strategies for this vulnerability should focus on implementing proper message authentication and integrity checks within the chat component. The most effective approach involves adding cryptographic signatures or message authentication codes to each chat message, ensuring that recipients can verify the true source of communications. Additionally, the application should implement strict validation of message source fields and maintain detailed audit logs of message transmissions. Users should be advised to verify message authenticity through out-of-band channels when possible, and administrators should consider implementing additional access controls to limit who can participate in sensitive chat sessions. Regular updates and patches should be deployed immediately upon availability, as this vulnerability can be exploited without requiring specialized knowledge or advanced attack capabilities.