failbreak

The term "failbreak" refers to a jailbreak that cannot be released to the general public, which makes it a fail to an extent. There are a variety of reasons a jailbreak will become a "failbreak". This term came about when chpwn showed a screenshot of his new iPhone 5 running Cydia shortly after its launch on September 19, 2012. Shortly afterward, usage of this term picked up, and on October 19, 2012, planetbeing tweeted that he upgraded the "failbreak" with a kernel exploit so that tweaks actually work on the iPhone 5, to make it "almost a full tethered jailbreak." This "failbreak" of sorts has existed for a while, since the iOS 4.0 days. If some of you will recall pod2g tweeted about a 2 year old exploit being closed, this is what he was referring to, the original "failbreak" being closed.

This is actually not how we define "failbreak": pod2g heard us using the term in an IRC channel once, and then extrapolated the meaning; chpwn then had to clarify what he meant on a Twitter post, and now everyone is using the term in a way we usually do not, and the distinction is important, as people assume we have things we don't.

Specifically, a "failbreak"i s one that has malfunctioning kernel patches that prevent Substrate from operating. I provide a tool called "vmcheck" that people developing jailbreaks use to "unit test" their patches, and when it fails... well, that's a "failbreak". If you ran that tool on the jailbreak from chpwn/pheonix, that tool would fail.

The term was actually first used years ago by chpwn on a released jailbreak as there was something wrong with it that caused Substrate to only work in some processes; I was then later using it with regards to jailbreaks where the kernel patches didn't support the various memory protection changes required by C Substrate.

failbreaks

• iOS 4.2.1 (Jailbreak Monte)
  • Access to iOS 4.2b3 beta for device
• iOS 6 on A6
  • Apple Developer account required
  • Developers under NDA

References

• @chpwn with jailbroken iPhone 5
• @pod2g confirming chpwn is trustable
• @chpwn mentioning the term the first time
• @planetbeing on "the kernel exploit"