StbiSharp

Problem

Control Flow Guard (CFG/CFI) protects the code flow integrity by ensuring that dynamic calls are made only to vetted functions. Trusted execution paths rely on the ability of the operating system to build a list of valid function targets. Certain functions can intentionally be disallowed to prevent malicious code from deactivating vulnerability mitigation features. A list of such invalid function targets can include publicly exported symbols. Applications that enhance control flow integrity through export suppression rely on libraries to mark their publicly visible symbols as suppressed. This is done for all symbols that are considered to be sensitive functions, and to which access should be restricted. It is considered dangerous to mix applications that perform export suppression with libraries that do not.

Problem

Control Flow Guard (CFG/CFI) protects the code flow integrity by ensuring that indirect calls are made only to vetted functions. This mitigation protects dynamically resolved function targets by instrumenting the code responsible for transferring execution control. Higher-level programming languages implement structured exception handling by managing their own code flow execution paths. As such, they are subject to code flow hijacking during runtime. Language-specific exception handling mitigation enforces execution integrity by instrumenting calls to manage execution context switching. Any deviation from the known and trusted code flow paths will cause the application to terminate. This makes malicious code less likely to execute.

Problem

On Linux, external symbols are resolved via the procedure linkage table (PLT) and the global offset table (GOT). Without any protection, both are writable at runtime and thus leave the executable vulnerable to pointer hijacking - an attack where the function address is overwritten with an address of a malicious function. Pointer hijacking can be mitigated by using full read-only relocations, which instruct the compiler to unify global offset tables into a single read-only table. This requires that all external function symbols are resolved at load-time instead of during execution, and may increase loading time for large programs.

Problem

Digital signatures are applied to applications, packages and documents as a cryptographically secured authenticity record. Signatures verify the origin and the integrity of the object they apply to. The integrity validation relies on the cryptographic strength of the encryption and the hash verification algorithm. If either of the two is considered weak by current standards, there is a chance the signed object could be maliciously modified, without triggering the integrity failure check.

Problem

Common compilers often embed source code information into executables for debugging purposes, usually by mapping symbols to source filenames or paths. While this is typically desirable in open-source software and standard tools, that information can be used to determine security weaknesses, code repository layout, trade secrets and similar sensitive information. Such symbols make it easier to reverse-engineer a closed source application.

Problem

Digital signatures are applied to applications, packages and documents as a cryptographically secured authenticity record. Signatures are made using digital certificates, which can either be purchased from certificate authorities or be self-issued. When a certificate is purchased from a certificate authority, the subject that requests it goes through an identity validation process. Depending on the certificate type, those checks can be basic or extended. Confirming the subject identity is a multi-step process, and the requesting subject can be mapped to its legal entity name only through extended validation of submitted documents. Extended identity validation typically costs more, and it takes longer for a certificate to be issued when this process is correctly followed.