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.

The second payload use an exploit in the kernel to get root access and privileges in order to jailbreak.