Each letter is a glass cane, a cylinder of glass made by pulling and twisting an arrangement of straight lines of colored glass embedded within clear glass. The top view shows the initial extruded arrangement, which is an easily recognized letter. The side view shows the pulled and twisted result, as simulated by our Virtual Glass software, and forms a challenging puzzle to decipher.

Tigress is a diversifying virtualizer/obfuscator for the C language that supports many defenses against both static and dynamic reverse engineering and de-virtualization attacks. Tigress is a source-to-source transformer - it takes a C source program as input and returns a new C program as output. An obfuscation script (actually, a long sequence of command line options) describes the sequences of transformations that should be applied to the functions of the program.

An excellent blog post on how Wordpress backdoors work, how they're hidden, and how they're used.