GitHub C2 profile malfunctioning on some situations

[armysick]

Describe the bug

For the GitHub profile to work with Athena, it is mandatory that the repository is not empty, and that the default branch is named "main".

In

Athena/Payload_Type/athena/athena/agent_code/Agent.Profiles.GitHub/GitHubProfile.cs

Line 101 in a2bfe47

var baseRef = await client.Git.Reference.Get(OWNER, REPO, $"heads/main");

will fail unless two conditions are met:

• Repository is not empty
• Branch main exists

Expected behavior
Either handle this edge case scenario (see additional data below);
Or describe these two conditions as a quick note on the setup documentation.

Additional data

Stack trace for "Git Repository is empty" Exception (empty repo):

   at Octokit.Connection.RunRequest(IRequest request, CancellationToken cancellationToken, Func`2 preprocessResponseBody) in /_/Octokit/Http/Connection.cs:line 798
   at Octokit.Connection.Run[T](IRequest request, CancellationToken cancellationToken, Func`2 preprocessResponseBody) in /_/Octokit/Http/Connection.cs:line 783
   at Octokit.ApiConnection.Get[T](Uri uri, IDictionary`2 parameters)
   at Agent.Profiles.GitHub.StartBeacon()

Stack trace for "Not Found" Exception (main branch does not exist):

   at Octokit.Connection.RunRequest(IRequest request, CancellationToken cancellationToken, Func`2 preprocessResponseBody) in /_/Octokit/Http/Connection.cs:line 798
   at Octokit.Connection.Run[T](IRequest request, CancellationToken cancellationToken, Func`2 preprocessResponseBody) in /_/Octokit/Http/Connection.cs:line 783
   at Octokit.ApiConnection.Get[T](Uri uri, IDictionary`2 parameters)
   at Agent.Profiles.GitHub.StartBeacon()

[checkymander]

Thanks for the report, and recommendations! @scottctaylor12 cc'ing the creator of that profile

[scottctaylor12]

Thanks for the detailed writeup @armysick! These are great suggestions that I will add to the C2 Profile documentation immediately. Rather than hardcoding the main branch, I will make that a configurable parameter in the near future.

[scottctaylor12]

The GitHub C2 Documentation has been updated with your suggestions. Feel free to install the latest version of the GitHub C2 Profile to see the updated documentation, or check them out at: https://github.com/MythicC2Profiles/github/blob/main/documentation-c2/github/_index.md
Thank you again for submitting this issue!