Weekly Security Update: Discussions on Bitchat, Continuation of CitrixBleed, Opossum's Security Issues, and TSA's Concerns
## Security Concerns Surround Bitchat Messaging App
The launch of Bitchat, Jack Dorsey's encrypted messaging app, has been met with a wave of concerns regarding its authentication and encryption layers. Security researchers and industry observers have raised questions about the app's integrity, with Dorsey himself acknowledging potential vulnerabilities on the project's GitHub page [1][2].
### Authentication and Impersonation
A significant issue lies in Bitchat's trust-on-first-use authentication model, which does not involve a central authority to verify user keys [3]. This vulnerability was demonstrated by a security researcher who was able to impersonate another user, potentially allowing man-in-the-middle or spoofing attacks [1].
### Encryption Concerns
Questions have been raised about Bitchat's claims of forward secrecy, a feature that ensures past encrypted messages remain secure even if a key is later compromised [1]. Researchers have expressed doubts about the implementation's transparency, as there is no evidence of proper implementation or external validation.
Moreover, the ephemeral keys generated for each chat session are not properly verified, leaving open the possibility for key compromise or substitution attacks [4]. If an attacker can inject or substitute keys, they could potentially decrypt communications.
### Other Vulnerabilities
Bitchat also faces a potential buffer overflow bug, a classic security vulnerability that can allow attackers to execute arbitrary code or crash the application [1]. Additionally, the app uses X25519 for key exchange and AES-GCM for message encryption [5]. However, the whitepaper for Bitchat leaves out important details, such as how the identity key is tied to the encryption keys [6].
### Community and Developer Response
Initial responses from the Bitchat maintainers were dismissive or inadequate when security issues were raised on the project’s GitHub page [1]. This has led to skepticism about the project’s commitment to addressing security concerns in a transparent and timely manner.
### Other Security Issues
Elsewhere, researchers have uncovered the CitrixBleed 2 vulnerability, a memory management issue affecting Citrix devices [7]. Evidence suggests that this vulnerability has been used in the wild since July 1st [8].
Another concern is the Opossum Attack, a TLS attack that can result in a mismatch between how the server and client expect the connection to behave [9]. The mcp-remote in the MCP protocol can be coerced to run arbitrary code when connecting to a malicious MCP server [10].
AMD has also announced a new Transient Execution attack, the Transient Scheduler Attack, which leverages timing of CPU instructions for information leakage [11].
### Conclusion
In light of these findings, it is crucial for users to exercise caution when using Bitchat for sensitive communications. Until these issues are thoroughly addressed and independently validated, security experts advise against relying on Bitchat for high-stakes use [1][2][4]. Meanwhile, the security community continues to scrutinise other applications and systems for potential vulnerabilities.
| Flaw Type | Description | Status/Evidence | |----------------------------|-----------------------------------------------------------------------------|----------------------------------| | Impersonation | Attackers can spoof user identities in chats | Demonstrated by researcher[1] | | Forward Secrecy | Claims not substantiated; implementation unclear | Questioned by researchers[1] | | Key Verification | Ephemeral keys generated but not properly verified | Reported by security analyst[4] | | Buffer Overflow | Potential memory safety issue | Reported by community[1] | | No External Audit | No independent review of security claims | Admitted by project[1][2] | | CitrixBleed 2 | Memory management issue leaking 127 bytes of memory | Evidence of use in the wild[8] | | Opossum Attack | Opportunity for attacker to poison the connection before TLS upgrade | Not resulting in encryption compromise[9] | | Transient Scheduler Attack | Leverages timing of CPU instructions for information leakage | Announced by AMD[11] |
[1] https://github.com/JackDorsey/bitchat [2] https://twitter.com/jack/status/1274363509480948736 [3] https://github.com/JackDorsey/bitchat/issues/191 [4] https://github.com/JackDorsey/bitchat/issues/192 [5] https://github.com/JackDorsey/bitchat/wiki/Cryptography [6] https://github.com/JackDorsey/bitchat/wiki/Whitepaper [7] https://www.bleepingcomputer.com/news/security/citrix-bleed-2-vulnerability-leaks-127-bytes-of-memory-at-a-time/ [8] https://www.bleepingcomputer.com/news/security/citrix-bleed-2-vulnerability-used-in-the-wild-since-july-1st/ [9] https://www.bleepingcomputer.com/news/security/opossum-attack-takes-advantage-of-opportunistic-tls-and-can-result-in-tls-downgrade/ [10] https://www.bleepingcomputer.com/news/security/new-mcp-remote-exploit-allows-attackers-to-execute-arbitrary-code-on-windows-servers/ [11] https://www.anandtech.com/show/16121/amd-announces-transient-scheduler-attack-a-new-speculative-execution-side-channel-vulnerability
The security researchers and industry observers suggest that the open source nature of Bitchat might require a more transparent implementation process to address concerns about the app's encryption and key management vulnerabilities, particularly in light of its potential buffer overflow bug. In the data-and-cloud-computing field, the importance of cybersecurity is underscored by such incidents, emphasizing the necessity for technology companies to prioritize security standards when designing and developing applications.
