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fix: strengthen anti-debug detection (Safe mode blocking startup check) (#76) #94

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Merged
mcpolo99 merged 1 commit into from
Jul 4, 2026
Merged

fix: strengthen anti-debug detection (Safe mode blocking startup check) (#76) #94

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9 changes: 7 additions & 2 deletions Confuser.Runtime/AntiDebug.Safe.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,12 @@ static void Initialize() {
"1".Equals(method.Invoke(null, new object[] { x + "_ENABLE_PROFILING" })))
Environment.FailFast(null);

// Blocking startup check: if a debugger is already attached when the module loads
// (e.g. the assembly was launched under a debugger / dnSpy's F5), fail immediately —
// before any user code runs — rather than only detecting it later on the async worker.
if (Debugger.IsAttached || Debugger.IsLogging())
Environment.FailFast(null);

var thread = new Thread(Worker);
thread.IsBackground = true;
thread.Start(null);
Expand All @@ -25,7 +31,6 @@ static void Worker(object thread) {
th = new Thread(Worker);
th.IsBackground = true;
th.Start(Thread.CurrentThread);
Thread.Sleep(500);
}
while (true) {
if (Debugger.IsAttached || Debugger.IsLogging())
Expand All @@ -34,7 +39,7 @@ static void Worker(object thread) {
if (!th.IsAlive)
Environment.FailFast(null);

Thread.Sleep(1000);
Thread.Sleep(200);
}
}
}
Expand Down
9 changes: 7 additions & 2 deletions Confuser.Runtime/AntiDebug.Win32.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,12 @@ static void Initialize() {
if (here != null && here.ProcessName.IndexOf("dnspy", StringComparison.OrdinalIgnoreCase) >= 0)
Environment.FailFast("");

// Blocking startup check: fail before any user code runs if a debugger is already
// attached when the module loads (managed or native), instead of only catching it
// later on the async worker thread where the app has already started.
if (Debugger.IsAttached || Debugger.IsLogging() || IsDebuggerPresent())
Environment.FailFast("");

var thread = new Thread(Worker);
thread.IsBackground = true;
thread.Start(null);
Expand Down Expand Up @@ -97,7 +103,6 @@ static void Worker(object thread) {
th = new Thread(Worker);
th.IsBackground = true;
th.Start(Thread.CurrentThread);
Thread.Sleep(500);
}
while (true) {
// Managed
Expand Down Expand Up @@ -129,7 +134,7 @@ static void Worker(object thread) {
if (!th.IsAlive)
Environment.FailFast("");

Thread.Sleep(1000);
Thread.Sleep(200);
}
}
}
Expand Down
15 changes: 15 additions & 0 deletions Confuser2.sln
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Original file line number Diff line number Diff line change
Expand Up @@ -205,6 +205,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "CrossFramework.WPF.Net8", "
EndProject
Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "CrossFramework.Library.Net10", "Tests\CrossFramework.Library.Net10\CrossFramework.Library.Net10.csproj", "{4458415A-0F5E-4136-B723-7A67955D6047}"
EndProject
Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "AntiDebug.Test", "Tests\AntiDebug.Test\AntiDebug.Test.csproj", "{47197200-B8CB-400A-B1BD-84975FEC8C28}"
EndProject
Global
GlobalSection(SolutionConfigurationPlatforms) = preSolution
Debug|Any CPU = Debug|Any CPU
Expand Down Expand Up @@ -1343,6 +1345,18 @@ Global
{4458415A-0F5E-4136-B723-7A67955D6047}.Release|x64.Build.0 = Release|Any CPU
{4458415A-0F5E-4136-B723-7A67955D6047}.Release|x86.ActiveCfg = Release|Any CPU
{4458415A-0F5E-4136-B723-7A67955D6047}.Release|x86.Build.0 = Release|Any CPU
{47197200-B8CB-400A-B1BD-84975FEC8C28}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
{47197200-B8CB-400A-B1BD-84975FEC8C28}.Debug|Any CPU.Build.0 = Debug|Any CPU
{47197200-B8CB-400A-B1BD-84975FEC8C28}.Debug|x64.ActiveCfg = Debug|Any CPU
{47197200-B8CB-400A-B1BD-84975FEC8C28}.Debug|x64.Build.0 = Debug|Any CPU
{47197200-B8CB-400A-B1BD-84975FEC8C28}.Debug|x86.ActiveCfg = Debug|Any CPU
{47197200-B8CB-400A-B1BD-84975FEC8C28}.Debug|x86.Build.0 = Debug|Any CPU
{47197200-B8CB-400A-B1BD-84975FEC8C28}.Release|Any CPU.ActiveCfg = Release|Any CPU
{47197200-B8CB-400A-B1BD-84975FEC8C28}.Release|Any CPU.Build.0 = Release|Any CPU
{47197200-B8CB-400A-B1BD-84975FEC8C28}.Release|x64.ActiveCfg = Release|Any CPU
{47197200-B8CB-400A-B1BD-84975FEC8C28}.Release|x64.Build.0 = Release|Any CPU
{47197200-B8CB-400A-B1BD-84975FEC8C28}.Release|x86.ActiveCfg = Release|Any CPU
{47197200-B8CB-400A-B1BD-84975FEC8C28}.Release|x86.Build.0 = Release|Any CPU
EndGlobalSection
GlobalSection(SolutionProperties) = preSolution
HideSolutionNode = FALSE
Expand Down Expand Up @@ -1434,6 +1448,7 @@ Global
{3942E3FD-06BC-470C-A1ED-BB18F2332B94} = {356BDB31-853E-43BB-8F9A-D8AC08F69EBB}
{30DC9F52-E08A-4EF0-B041-04AED6135C3D} = {356BDB31-853E-43BB-8F9A-D8AC08F69EBB}
{4458415A-0F5E-4136-B723-7A67955D6047} = {356BDB31-853E-43BB-8F9A-D8AC08F69EBB}
{47197200-B8CB-400A-B1BD-84975FEC8C28} = {356BDB31-853E-43BB-8F9A-D8AC08F69EBB}
EndGlobalSection
GlobalSection(ExtensibilityGlobals) = postSolution
SolutionGuid = {0D937D9E-E04B-4A68-B639-D4260473A388}
Expand Down
13 changes: 13 additions & 0 deletions Tests/AntiDebug.Test/AntiDebug.Test.csproj
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Original file line number Diff line number Diff line change
@@ -0,0 +1,13 @@
<Project Sdk="Microsoft.NET.Sdk">

<PropertyGroup>
<TargetFramework>net462</TargetFramework>
<IsPackable>false</IsPackable>
</PropertyGroup>

<ItemGroup>
<ProjectReference Include="..\Confuser.UnitTest\Confuser.UnitTest.csproj" />
<ProjectReference Include="..\AntiTamper\AntiTamper.csproj" />
</ItemGroup>

</Project>
29 changes: 29 additions & 0 deletions Tests/AntiDebug.Test/AntiDebugTest.cs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,29 @@
using System.Threading.Tasks;
using Confuser.Core;
using Confuser.Core.Project;
using Confuser.UnitTest;
using Xunit;
using Xunit.Abstractions;

namespace AntiDebug.Test {
public sealed class AntiDebugTest : TestBase {
public AntiDebugTest(ITestOutputHelper outputHelper) : base(outputHelper) { }

// Regression guard: anti-debug injects a startup check plus a background watchdog into
// the module cctor. This verifies that an assembly protected with anti-debug still runs
// normally when it is NOT being debugged — i.e. the strengthened checks (blocking startup
// check, faster polling) do not false-positive on a plain process launch. The test runner
// launches the subject as an ordinary child process with no debugger attached, so a healthy
// build must produce START / <resource> / END and exit code 42.
[Theory]
[InlineData("safe")]
[InlineData("win32")]
[Trait("Category", "Protection")]
[Trait("Protection", "anti debug")]
public Task ProtectAntiDebugAndExecute(string mode) =>
Run("AntiTamper.exe",
new[] { "This is a test." },
new SettingItem<Protection>("anti debug") { { "mode", mode } },
"_antidebug_" + mode);
}
}