1. A computer system comprising: one or more memories storing computer-readable code; and one or more hardware processors, configured in response to executing the computer-readable code to cause the computer system to perform: accessing one or more seeding specifications and a program comprising computer-readable code; applying the one or more seeding specifications to the program to identify for analysis seeds comprising strings for corresponding identified string variables; and tracking flows emanating from the identified seeds and performing at least the following for the tracking: computing an integral offset into a tracked string variable for any statements causing such a computation; providing a string representation based on the computed integral offset, wherein the provided string representation comprises a value of the integral offset and an indication of the corresponding tracked string variable; and modeling string manipulations of the tracked string variables using the string representations, wherein tracking further comprises, for string manipulations other than statements performing the index-sensitive string manipulation and statements causing computation of an integral offset into a tracked string variable, applying an operation to the string representation while preserving the integral offset.