Security issues in volunteer computing

Many types of attacks are possible in volunteer computing.

• Result falsification. Attackers return incorrect results.
• Credit falsification. Attackers return results claiming more CPU time than was actually used.
• Malicious executable distribution. Attackers break into a BOINC server and, by modifying the database and files, attempt to distribute their own executable (e.g. a virus program) disguised as a BOINC application.
• Overrun of data server. Attackers repeatedly send large files to BOINC data servers, filling up their disks and rendering them unusable.
• Theft of participant account information by server attack. Attackers break into a BOINC server and steal email addresses and other account information.
• Theft of participant account information by network attack. Attackers exploit the BOINC network protocols to steal account information.
• Theft of project files. Attackers steal input and/or output files.
• Intentional abuse of participant hosts by projects. A project intentionally releases an application that abuses participant hosts, e.g. by stealing sensitive information stored in files.
• Accidental abuse of participant hosts by projects. A project releases an application that unintentionally abuses participant hosts, e.g. deleting files or causing crashes.

BOINC provides mechanisms to reduce the likelihood of some of these attacks.

Result falsification

This can be probabilistically detected using redundant computing and result verification: if a majority of results agree (according to an application-specific comparison) then they are classified as correct.

Credit falsification

This can be probabilistically detected using redundant computing and credit verification: each participant is given the minimum credit from among the correct results (or some other algorithm, such as the mean or median of claimed credits).

Malicious executable distribution

BOINC uses code signing to prevent this. Each project has a key pair for code signing. The private key should be kept on a network-isolated machine used for generating digital signatures for executables. The public key is distributed to, and stored on, clients. All files associated with application versions are sent with digital signatures using this key pair.

Even if attackers break into a project's BOINC servers, they will not be able to cause clients to accept a false code file.

BOINC provides a mechanism by which projects can periodically change their code-signing key pair. The project generates a new key pair, then (using the code-signing machine) generates a signature for the new public key, signed with the old private key. The core client will accept a new key only if it's signed with the old key. This mechanism is designed to prevent attackers from breaking into a BOINC server and distributing a false key.

Denial of server attacks on data servers

Each result file has an associated maximum size. Each project has a upload authentication key pair. The public key is stored on the project's data servers. Result file descriptions are sent to clients with a digital signature, which is forwarded to the data server when the file is uploaded. The data server verifies the file description, and ensures that the amount of data uploaded does not exceed the maximum size.

Theft of participant account information by server attack

Each project must address theft of private account information (e.g. email addresses) using conventional security practices. All server machines should be protected by a firewall, and should have all unused network services disabled. Access to these machines should be done only with encrypted protocols like SSH. The machines should be subjected to regular security audits.

Projects should be undertaken only by organizations that have sufficient expertise and resources to secure their servers. A successful attack could discredit all BOINC-based projects, and public-participation computing in general.

Theft of participant account information by network attack

Attackers sniffing network traffic could get a user's account key, and use them to get the user's email address, or change the user's preferences. BOINC does nothing to prevent this.

Theft of project files

The input and output files used by BOINC applications are not encrypted. Applications can do this themselves, but it has little effect since data resides in cleartext in memory, where it is easy to access with a debugger.

Intentional abuse of participant hosts by projects

BOINC uses account-based sandboxing: applications run under a specially-created account

(Mac/Linux? version 5.4+, Windows version 6+). If your system's file and directory permissions are set appropriately, applications will have no access to files outside of the BOINC directory.

Accidental abuse of participant hosts by projects

BOINC prevents some problems: for example, it detects when applications use too much disk space, memory, or CPU time, and aborts them. Projects can minimize the likelihood of causing problems by pre-released application testing. Projects should test their applications thoroughly on all platforms and with all input data scenarios before promoting them to production status.