Runtime Module Crypter in Python 3 with advanced functionality, Bypass VM, Encrypt Source with AES & Base64 Encryption | Evil Code is executed by bruteforcing
A better version of Xencrypt.Xencrypt it self is a Powershell runtime crypter designed to evade Runtime Modul Crypter VB6 Codet V.1
A Runtime Crypter encrypts the specified file and when executed (ran), … Delete all the code in each module one after another until the …
I just want to show you how the basic runtime Module crypter works. … Now, double click on the second module, and put in the RunPe module in it.
Bypassing Static Analysis With a Custom Crypter. One of the most well-documented and easiest ways to bypass static analysis is to encrypt …
Runtime module crypter is crypter that is FUD when you execute your crypted file. Runtime module crypter use RunPe module, which inject your
What’s Crypter? Crypter’s are programs used to encrypt your virus server and make it FUD from Anti-Virus software’s. You can find many free crypter’s, here on HackForums that are FUD. Crypter’s can be coded in different programming languages: Visual Basic .NET, Visual Basic 2006, Delphi, C++ etc. You can find some source code’s here, in this thread (click thread, it’s link). Crypters works something like this: You open Crypter.exe, then choose Server and then click crypt button. What do I need to know about crypter? Well, very important thing about crypter is Stub. Stub must be in same folder with crypter or it won’t crypt it. I Builder – Crypters builder is used to encrypt the selected file. Some crypters can be Runtime and some Scantime only. Runtime FUD are Fully Undetected from Anti-Viruses when you run the crypted server and AV doesn’t detects. Scantime is when you scan it with Anti-Virus. Smile II Stub – Crypters builder use Stub to encrypt & split builders data with stub and make new FUD-ed file. III EOF – EOF aka. End-Of-File support means that your crypter can work with End-Of-File server’s. Some server’s will just crash or won’t work when you crypt and if your crypter doesn’t support EOF it won’t end the terminal unless End-Of-File ends it. IV Scantime – Scantime crypter is crypter that is FUD from all Anti-Viruses when you scan it. But it will be detected when you execute crypted scantime server, so its important to have RunPe module (read down). V Runtime – Runtime crypter is crypter that is FUD when you execute your crypted file. Runtime crypter use RunPe module, which inject your Virus with some process from TaskMangr and make it fully un-visible from TaskManager process list. Encryption Algorithms? This is list of famous Encryption
Windows Defender is enabled by default in all modern versions of Windows making it an important mitigation for defenders and a potential target for attackers. While Defender has significantly improved in recent years it still relies on age-old AV techniques that are often trivial to bypass. In this post we’ll analyse some of those techniques and examine potential ways they can be bypassed.
Before diving into Windows Defender we wanted to quickly introduce the main analysis methods used by most modern AV engines:
Static Analysis – Involves scanning the contents of a file on disk and will primarily rely on a set of known bad signatures. While this is effective against known malware, static signatures are often easy to bypass meaning new malware is missed. A newer variation of this technique is machine learning based file classification which essentially compares static features against known good and bad profiles to detect anomalous files.
Process Memory/Runtime Analysis – Similar to the static analysis except running process memory is analysed instead of files on disk. This can be more challenging for attackers as it can be harder to obfuscate code in memory as its executing and off the shelf payloads are easily detected.
It’s also worth mentioning how scans can be triggered:
File Read/Write – Whenever a new file is created or modified this can potentially trigger the AV and cause it to initiate a scan of the file.
Periodic – AV will periodically scan systems, daily or weekly scans are common and this can involve all or just a subset of the files on the system. This concept also applies to scanning the memory of running processes.
Suspicious Behaviour – AV will often monitor for suspicious behaviour (usually API calls) and use this to trigger a scan, again this could be of local files or process memory.
In the next few sections we’ll discuss potential bypass techniques in more detail.
Runtime Module Crypter Bypassing Static Analysis With a Custom Crypter
One of the most well-documented and easiest ways to bypass static analysis is to encrypt your payload and decrypt it upon execution. This works by creating a unique payload every time rendering static file signatures ineffective. There are multiple open source projects which demonstrate this (Veil, Hyperion, PE-Crypter etc.) however we also wanted to test memory injection techniques so wrote a custom crypter to incorporate them in the same payload.
The crypter would take a “stub“ to decrypt, load and execute our payload and the malicious payload itself. Passing these through our crypter would combine them together into our final payload which we can execute on our target.
The proof of concept we created included support for a number of different injection techniques that are useful to test against AVs including local/remote shellcode injection, process hollowing and reflective loading. Parameters for these techniques were passed in the stub options.
All of the above techniques were able to bypass Windows Defender’s static file scan when using a standard Metasploit Meterpreter payload. However, despite execution succeeding we found that Windows Defender would still kill the Meterpreter session when commands such as shell/execute were used. But why?
Analysing Runtime Analysis
As mentioned earlier in this post memory scanning can be periodic or “triggered” by specific activity. Given that our Meterpreter session was only killed when shell/execute was used it seemed likely this activity was triggering a scan.
Runtime module crypter After confirming Windows Defender memory scanning was being triggered by specific APIs, the next question was how can we bypass it? One simple approach would be to avoid the APIs that trigger Windows Defender’s runtime scanner but that would mean manually rewriting Metasploit payloads which is far too much effort. Another option would be to obfuscate the code in memory, either by adding/modifying instructions or dynamically encrypting/decrypting our payload in memory when a scan a detected. But is there another way?
Well one thing that works in an attacker’s favour is that the virtual memory space of processes is huge being 2 GB in 32 bits and 128 TB in 64 bits. As such AVs won’t typically scan the whole virtual memory space of a process and instead look for specific page allocations or permissions, for example MEM_PRIVATE or RWX page permissions. Reading through the Microsoft documentation though you’ll see one permission in particular that is quite interesting for us, PAGE_NOACCESS. This “Disables all access to the committed region of pages. An attempt to read from, write to, or execute the committed region results in an access violation.” which is exactly the kind of behaviour we are looking for. And quick tests confirmed that Windows Defender would not scan pages with this permission, awesome we have a potential bypass!
Runtime Module Crypter To weaponize this we’d just need to dynamically set PAGE_NOACCESS memory permissions whenever a suspicious API was called (as that would trigger a scan) then revert it back once the scan is done. The only tricky bit here is we’d need to add hooks for any suspicious calls to make sure we can set permissions before the scan is triggered.
Bringing this all together, we’d need to:
- Install hooks to detect when a Windows Defender trigger function (CreateProcess) is called
- When CreateProcess is called the hook is triggered and Meterpreter thread is suspended
- Set payload memory permissions to PAGE_NOACCESS
- Wait for scan to finish
- Set permission back to RWX
- Resume the thread and continue execution
We’ll walk through the code for this in the next section.
Digging into the hooking code
We started by creating a function installHook which would take the address of CreateProcess as well as the address of our hook as input then update one with the other.
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