The Mega file-sharing service has launched a vulnerability reward program that will pay up to ¬10,000 (around US$13,600) for every serious security flaw found in the platform and reported responsibly. The rules of the program were laid out in a blog post published Saturday.
The type of bugs that qualify for a reward include: SQL injection and XSS (cross-site scripting) flaws that can result in remote code execution on Mega's servers or in any client browser; issues that defeat the site's cryptographic security model resulting in unauthorized access to encryption keys or user data; access control bypasses that allow the destruction of keys or data and issues that can result in an account's data being compromised as the result of its associated email address being hacked.
The type of security issues that won't be rewarded include: issues that require user interaction like phishing and other forms of social engineering attacks; issues resulting from the use of weak passwords; issues that require a large number of server requests (brute force); any issues that result from the use of compromised client machines; issues that require an unsupported or outdated browser; vulnerabilities in third-party services, for example those run by resellers; denial-of-service issues; issues that require physical access to data centers; issues that involve the use of forged SSL certificates; cryptographic deficiencies that require extreme computational power to exploit, like the prediction of random numbers; or any other bugs that don't affect the integrity, availability and confidentiality of user data.
The launch of the Mega vulnerability reward program follows criticism from the security and cryptography community regarding some of the service's design decisions and claims that the service cannot deliver on its security and privacy promises to users.
Following Mega's launch two weeks ago, security experts pointed out several issues that could threaten the security of service like the inclusion of password hashes in sign-up confirmation links sent via email, the use of a weak cryptographic hash function to verify the integrity of JavaScript code on Mega's secondary servers, and the lack of proper entropy -- randomness -- during the encryption key generation process.
Mega's creators responded to these concerns in an earlier blog post, acknowledging some of them, but dismissing others.
"Mega's open source encryption remains unbroken! We'll offer 10,000 EURO to anyone who can break it," Mega founder Kim Dotcom said Friday on Twitter.
In response to that Twitter message, some people argued that the validity of that statement depends on one's interpretation of "broken" in a cryptographic context.
For example, Mega's administrators said that "anything requiring extreme computing power (2^60 cryptographic operations+) or a working quantum computer" doesn't qualify for a reward. "This includes allegedly predictable random numbers -- you qualify only if you are able to show an actual weakness rather than general conjecture," they said.
In a follow-up discussion on Twitter between Mega's chief programmer Bram van der Kolk and Nadim Kobeissi, developer of the encrypted instant messaging program Cryptocat, Kobeissi said: "Dude, your hashing algorithm has collisions in the space 2^64, and you think that 'doesn't qualify'???"
As part of the vulnerability reward program announced on Saturday, Mega has also launched a brute-force challenge that offers the maximum reward of $13,600 to anyone who decrypts a particular file encrypted with Mega's encryption scheme or to anyone who can crack the password from a hash included in a sign-up confirmation link.
Two weeks ago, a researcher named Steve Thomas, known online as "Sc00bz," released a tool called MegaCracker that can extract password hashes from Mega sign-up confirmation links sent via email and can attempt to crack them using a dictionary attack.
In response, Mega's administrators said at the time that the tool is "an excellent reminder not to use guessable/dictionary passwords." The new password hash cracking challenge is likely aiming to underscore that point by using a very strong password that cannot easily be recovered using dictionary attacks.
The value of each reward will be decided on a case by case basis by the Mega administrators depending on the flaw's complexity and potential impact. "The decision whether you qualify and how much you earn is at our discretion, and while we will be fair and generous, you agree to accept our verdict as final," the Mega administrators said.
If the same bug is reported by multiple individuals, only the person who reported it first will earn the reward. After the bug has been patched, the reporter is free to disclose it to the general public.