DLL Refresher detection

[0xElessar]

Hello,

thank you for providing such a great framework! Amazing work.

Unfortunately, the DLL Refresher code is detected by some AV, for example: NOD32. Example command:

../ScareCrow/ScareCrow -I beacon-sourcepoint-test1.bin -Loader dll -etw -domain www.microsoft.com

When I disabled refreshing and ETW, the DLL bypasses NOD32 though. I tried modifying the Struct.go, but editing is pretty hard due to "variable set and unused" compilation error.

Any chance that you can implement ETW and Refresher functionality as reflected (encrypted) DLL files? My Goland skills cannot do that in this language :(

thanks Rafal

[GetRektBoy724]

Might wanna try my program,SharpUnhooker. Not only unhooks the whole API DLL, but it also disables AMSI (if loaded) and ETW. And also, usually "variable set and unused" is only a warning (in most programming languages).

[0xElessar]

Thank you, @GetRektBoy724 . Thank you for Csharp code. Very useful! Another one in C code is https://github.com/rsmudge/unhook-bof

But it would be great to integrate this code safely in this project. As it simplifies the pipeline very nicely :)

Indeed, "variable set and unused" is usually a warning, but in Goland seems to be a hard error :(

[GetRektBoy724]

Thank you, @GetRektBoy724 . Thank you for Csharp code. Very useful! Another one in C code is https://github.com/rsmudge/unhook-bof

But it would be great to integrate this code safely in this project. As it simplifies the pipeline very nicely :)

[Tylous]

Hello,

thank you for providing such a great framework! Amazing work.

Unfortunately, the DLL Refresher code is detected by some AV, for example: NOD32. Example command:

../ScareCrow/ScareCrow -I beacon-sourcepoint-test1.bin -Loader dll -etw -domain www.microsoft.com

When I disabled refreshing and ETW, the DLL bypasses NOD32 though. I tried modifying the Struct.go, but editing is pretty hard due to "variable set and unused" compilation error.

Any chance that you can implement ETW and Refresher functionality as reflected (encrypted) DLL files? My Goland skills cannot do that in this language :(

thanks Rafal

I could look to make it a encrypted DLL in the next update however I do not think would stop the detection. What happens if you use the refresh with say wscript or control loaders? Does the same issue occur?

[0xElessar]

Hello @Tylous,

thank you again for the tool. I tried binary, DLL and wscript. NOD32 detected all of them with the same signature Kryptik.E or something similar. It was a static AV file check, no execution was required.

I checked deeper with DLL function. I found that this function triggers the detection:

func {{.Variables.Reloading}}(name string) error {
        {{.Variables.dll}}, {{.Variables.error}} := ioutil.ReadFile(name)
        if {{.Variables.error}} != nil {
            return {{.Variables.error}}
        }
[...] 

When I removed the content of this function detection stopped. The same happened when I used 'unmodified' flag. I attempted to check what exactly triggers detection, but modification of this code is pretty hard and time-consuming due to the error message ("declared but unused"). I changed "PAGE_EXECUTE_READWRITE" memory flag too, but this did not impact the detection.

I thought if this functionality is encrypted and loaded as reflective DLL, no signature can match it, especially as your tool will make the encryption unique every time it runs. Anyway, this is just an idea. If I am wrong, apologies!

thanks

[Tylous]

hmmm interesting. If it is this, try changing the variable name to adsfa and replace if {{.Variables.error}} != nil { return {{.Variables.error}} } with if {{.Variables.error}} != nil { }

[0xElessar]

I am sorry, @Tylous . I think you misunderstood me.

I meant the whole function starting with func {{.Variables.Reloading}}(name string) error {

The function contains the reference to:

{{.Variables.dll}}, {{.Variables.error}} := ioutil.ReadFile(name)
[...]
{{.Variables.x}} := {{.Variables.file}}.Section(".text")
[...]
{{.Variables.loaddll}}, {{.Variables.error}} := windows.LoadDLL(name)
[...]
{{.Variables.runfunc}}, _ := NtProtectVirtualMemory(
[...]

Apologies if I did not make myself clear.

[Tylous]

All good, I think I have an idea of what to do. Gonna start building and testing this week.

[0xElessar]

All good, I think I have an idea of what to do. Gonna start building and testing this week.

Great stuff. Much appreciated, @Tylous !

[Tylous]

Update: I am working on an updated version to address this and some other things. Please bare with me, while I test it all.

[Tylous]

Should be addressed in Patch 3.0

[0xElessar]

Thank you very much, @Tylous !

[Tylous]

Closing this issue if there are further issues related to this feel free to re-open.