Google Project Zero security researchers have found what they claim is a "critical flaw" in the Transmission BitTorrent client that could enable cyber crooks to take control of users' computers.
According to Project Zero, the client is vulnerable to a DNS re-binding attack that effectively tricks the PC into accepting requests via port 9091 from malicious websites that it would (and should) ordinarly ignore.
The flaw could enable attackers to execute all kinds of attacks, including remote code execution, and works in both Chrome and Firefox - other browsers will almost certainly be vulnerable too.
Google Project Zero researcher Tavis Ormandy published proof of concept attack code last week in order to demonstrate the severity of the security flaw and to force the developers of Transmission to rush out a patch. He described it as a "relatively low complexity exploit", making it easy for attackers to deploy.
But Ormandy claims that the open-source developers responsible for maintaining Transmission haven't been quick to respond to his communications.
While the flaw was uncovered in November, they claimed that it would not be possible to produce a patch for weeks - possibly even busting Project Zero's unilateral 90-day disclosure rule. That would be a first for an open-source project, Ormandy claimed.
Writing on Twitter, Ormandy warned that it was not the only BitTorrent application vulnerable to the DNS-rebinding flaw. Rather, it is the "first of a few remote code execution flaws in various popular torrent clients".
First of a few remote code execution flaws in various popular torrent clients, here is a DNS rebinding vulnerability Transmission, resulting in arbitrary remote code execution. https://t.co/kAv9eWfXlG— Tavis Ormandy (@taviso) January 11, 2018
Publicising details of the attack appears to have done the trick of forcing the developers to rush out a patch, but this has not been applied in all the software that uses the Transmission protocol, Ormandy warned.
In a follow up to his original November post warning of a security vulnerability, Ormandy last week wrote: "I'm finding it frustrating that the Transmission developers are not responding on their private security list, I suggested moving this into the open so that distributions can apply the patch independently. I suspect they won't reply, but let's see.
"I've never had an open-source project take this long to fix a vulnerability before, so I usually don't even mention the 90-day limit if the vulnerability is in an open source project.
"I would say the average response time is measured in hours rather months if we're talking about open source."
Transmission is one of a number of BitTorrent peer-to-peer file sharing clients.
Rather than a centralised hub-and-spoke system for distributing files and data, shared files are decentralised, but publicised via the software that utilises the protocol. If anyone in the network wants a file, it is downloaded in 'pieces' from the source or sources.
Peer-to-peer file sharing, however, has gained a reputation as a distribution mechanism for pirated software, television shows and films.
However, the protocol is also used for many legitimate file-distribution purposes, such as software and other downloads by legitimate vendors in order to reduce the stresses on networks that more centralised distribution systems can cause.
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