LangSec Revisited: Input Security Flaws of the Second Kind

We consider a simple classification of input flaws in two categories: (1) flaws in processing input, with buffer overflows in parsers as the classic example, and (2) flaws in forwarding input to some other system, aka injection flaws, with SQL injection and XSS as classic examples. The LangSec approach identifies common root causes for both categories of flaws, but much of the LangSec literature and efforts focus on the first category of flaws, especially on techniques to eliminate parser bugs. Therefore we take a look at some existing approaches to tackling the second category of flaws, to identify (anti)patterns and place these in the LangSec perspective.