Star

Star is a userland jailbreak from comex that utilizes 3 unknown exploits (2 new exploits, and 1 from Spirit) to jailbreak iOS 3.1.2 and later. Star warns that 3.1.2 and 3.1.3 are known to fail though, and that performing a fresh restore to 4.0 is recommended. It can be used via Jailbreakme.

Payloads

The first payload is deployed via a http redirect to a prepared pdf file. The PDF contains a CFF font with a malformed type 2 charstring, which contains commands to repeatedly push and duplicate random numbers onto an "argument stack". Presumably this crashes the font parser.