Researchers from ETH Zurich have uncovered vital safety vulnerabilities in a number of extensively used end-to-end encrypted (E2EE) cloud storage companies.
The cryptographic flaws might permit attackers to bypass encryption, compromise file confidentiality, tamper with knowledge, and even inject unauthorised recordsdata into customers’ storage.
The research analysed 5 E2EE cloud storage suppliers—Sync, pCloud, Seafile, Icedrive, and Tresorit—which collectively serve an estimated 22 million customers worldwide. Every of the companies guarantees sturdy encryption to safeguard recordsdata from unauthorised entry, even by the service supplier.
Nonetheless, researchers Jonas Hofmann and Kien Tuong Truong found that 4 of the 5 have extreme flaws that may weaken protections. Introduced on the ACM Convention on Pc and Communications Safety (CCS), their findings spotlight potential gaps within the E2EE safety guarantees made by suppliers.
Tresorit stands out however isn’t flawless
Of the companies examined, Tresorit demonstrated the fewest vulnerabilities, with solely minor dangers of metadata tampering and non-authentic keys throughout file sharing. Though much less extreme, these points might nonetheless pose dangers in sure situations. In distinction, the opposite 4 companies exhibited extra substantial safety gaps, growing the probabilities of knowledge publicity or tampering.
Key vulnerabilities and reasonable threats to E2EE
To judge the energy of E2EE safety, researchers examined ten completely different assault situations, assuming the attacker had already gained management over a cloud server with permissions to learn, modify, or inject knowledge. Although this degree of entry is unlikely, the research contends that E2EE ought to be efficient even below such situations. Some notable vulnerabilities are:
- Unauthenticated Key Materials: Each Sync and pCloud had been discovered to have unauthenticated encryption keys, permitting attackers to insert their very own keys, decrypt recordsdata, and entry delicate knowledge.
- Public key substitution: Sync and Tresorit had been susceptible to unauthorised key substitute throughout file sharing, permitting attackers to intercept or change recordsdata.
- Protocol downgrade assault: The protocols utilized by Seafile allowed for a downgrade to weaker encryption requirements, making it extra susceptible to brute-force assaults.
Different dangers had been recognized in Icedrive and Seafile, which used unauthenticated encryption modes, permitting attackers to switch and corrupt file contents. Moreover, vulnerabilities within the “chunking” course of throughout a number of companies might compromise file integrity by permitting attackers to reorder, take away, or alter file items.
Supplier gives responses and subsequent steps
In April 2024, the researchers shared their findings with Sync, pCloud, Seafile, and Icedrive, adopted by Tresorit in September. Responses diverse, with Sync and pCloud but to reply, Seafile getting ready to patch the protocol downgrade difficulty, and Icedrive declining to deal with the issues. Tresorit acknowledged receipt however declined to talk extra.
In keeping with a current BleepingComputer report, Sync indicated that they’re “fast-tracking fixes” and have already resolved among the documented knowledge leak points with file-sharing hyperlinks.
ETH Zurich researchers imagine these safety flaws are frequent throughout many E2EE cloud storage platforms, underscoring the necessity for additional investigation and a standardised protocol to make sure safe encryption within the business.
(Picture by Roman)
See additionally: Why firms proceed to battle with cloud visibility – and code vulnerabilities
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