Blueprint

A modular source code templater.

Configuration

Blueprint expects to receive a JSON configuration file which looks like the following:

{
    "filters": [
        "crypto.AES",
        "fmt.HexArray",
        "io.Content"
    ],
    "targets": [
        {
            "input": "Example.h.tpl",
            "output": "Example.h",
            "variables": {
                "EXAMPLE_VARIABLE": "EXAMPLE_VALUE",
            }
        }
    ]
}

The configuration is comprised of an arbitrary number of file targets. Blueprint operates on those targets by reading the input file of each target, performing templating on it, and writing the result to the output file, replacing any variables (found in the variables section) with their values. Moreover, an array of filters is defined in the config, controlling which filters will be imported (and thus be available for usage) in this configuration.

Templating

Blueprint utilizes Jinja for templating. Building upon the configuration in the above example, here is Example.h.tpl:

unsigned char key[] = { {{ AES_KEY | hexarr }} };
unsigned char iv[] = { {{ AES_IV | hexarr }} };
unsigned char payload[] = { {{ "payload.bin" | content | aes | hexarr }} };
usigned char example = "{{ EXAMPLE_VARIABLE }}";

Everything defined in {{ }} blocks is going to be evaluated by Blueprint. Inside such blocks, Jinja syntax is valid, along with filters defined by Blueprint modules. Filters receive an input (the expression before the pipe |) and return an output. They can also be chained together to create intricate templating functionality. Many filters also apply their own replacements to the processed target file, e.g. the XOR filter which also replaces XOR_KEY in the file with the random key generated for XORing.

Filters

For documentation regarding each filter refer to the README file inside the filter's directory. Here is a list of the available filters:

• io.Content
• io.Output
• crypto.XOR
• crypto.AES
• fmt.HexArray
• fmt.DecArray
• hashing.DJB2

Custom Modules

For documentation regarding creating your own Blueprint filters, refer to this README.

Detailed Analysis

A more detailed analysis of Blueprint and its features can be found on our blog. A step-by-step use case along with example code can be found on our second artictle From traditional to templated malware.

Author

Nick Aliferopoulos

Community

Join the Hackcraft community discord server here. On the server you can receive support and discuss issues related to Blueprint.