BinaryObjectScanner/BurnOutSharp/PackerType/NSIS.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using BurnOutSharp.ExecutableType.Microsoft;
using BurnOutSharp.Matching;

namespace BurnOutSharp.PackerType
{
    public class NSIS : IContentCheck
    {
        /// <inheritdoc/>
        public List<ContentMatchSet> GetContentMatchSets() => null;

        /// <inheritdoc/>
        public string CheckContents(string file, byte[] fileContent, bool includeDebug = false)
        {
            // TODO: Implement resource finding instead of using the built in methods
            // Assembly information lives in the .rsrc section
            // I need to find out how to navigate the resources in general
            // as well as figure out the specific resources for both
            // file info and MUI (XML) info. Once I figure this out,
            // that also opens the doors to easier assembly XML checks.

            // TODO: Use this instead of the seek inside of `.rsrc` when that's fixed
            //string description = Utilities.GetManifestDescription(fileContent);

            // Get the sections from the executable, if possible
            PortableExecutable pex = PortableExecutable.Deserialize(fileContent, 0);
            var sections = pex?.SectionTable;
            if (sections == null)
                return null;

            // Get the .rsrc section, if it exists
            var rsrcSection = sections.FirstOrDefault(s => Encoding.ASCII.GetString(s.Name).StartsWith(".rsrc"));
            if (rsrcSection != null)
            {
                int sectionAddr = (int)rsrcSection.PointerToRawData;
                int sectionEnd = sectionAddr + (int)rsrcSection.VirtualSize;
                var matchers = new List<ContentMatchSet>
                {
                    // Nullsoft Install System
                    new ContentMatchSet(
                        new ContentMatch(new byte?[]
                        {
                            0x4e, 0x75, 0x6c, 0x6c, 0x73, 0x6f, 0x66, 0x74,
                            0x20, 0x49, 0x6e, 0x73, 0x74, 0x61, 0x6c, 0x6c,
                            0x20, 0x53, 0x79, 0x73, 0x74, 0x65, 0x6d
                        }, start: sectionAddr, end: sectionEnd),
                    GetVersion, "NSIS"),
                };

                string match = MatchUtil.GetFirstMatch(file, fileContent, matchers, includeDebug);
                if (!string.IsNullOrWhiteSpace(match))
                    return match;
            }

            // Get the .data section, if it exists
            var dataSection = sections.FirstOrDefault(s => Encoding.ASCII.GetString(s.Name).StartsWith(".data"));
            if (dataSection != null)
            {
                int sectionAddr = (int)dataSection.PointerToRawData;
                int sectionEnd = sectionAddr + (int)dataSection.VirtualSize;
                var matchers = new List<ContentMatchSet>
                {
                    // NullsoftInst
                    new ContentMatchSet(
                        new ContentMatch(new byte?[]
                        {
                            0x4E, 0x75, 0x6C, 0x6C, 0x73, 0x6F, 0x66, 0x74,
                            0x49, 0x6E, 0x73, 0x74
                        }, start: sectionAddr, end: sectionEnd),
                    "NSIS"),
                };

                string match = MatchUtil.GetFirstMatch(file, fileContent, matchers, includeDebug);
                if (!string.IsNullOrWhiteSpace(match))
                    return match;
            }

            return null;
        }

        public static string GetVersion(string file, byte[] fileContent, List<int> positions)
        {
            try
            {
                int index = positions[0];
                index += 24;
                if (fileContent[index] != 'v')
                    return "(Unknown Version)";

                var versionBytes = new ReadOnlySpan<byte>(fileContent, index, 16).ToArray();
                var onlyVersion = versionBytes.TakeWhile(b => b != '<').ToArray();
                return Encoding.ASCII.GetString(onlyVersion);
            }
            catch
            {
                return "(Unknown Version)";
            }
        }
    }
}