![]() We are just counting until we reach the value 12341234, and pushing/poping the same value from the stack. ![]() To do that, we repeat this code 10 times before we execute the binary, in the nop sled that we prepared before: After that the real binary code is going to be executed outside the Kaspersky sandbox. We add a delay to let some seconds pass while AV is scanning the file, we will reach the maximum time scan allowed for scanning a single file and the scan is going to stop. We know that we bypassed the static scan, but how to bypass the dynamic one? I’ve read about this trick in this blog post: It seems that the AV it’s also doing a dynamic scan of the file. We scan the file with Kaspersky and it detects it again, with the same signature. I leave a 200 Nop sled before the decoder, and I implement the decoder and the registers recovery at the end. So it seems that we bypassed the static scan of the file. Now it’s the moment to scan the file, and Kaspersky doesn’t detect it, but our file doesn’t have the decoder stub. So I implement the encoder to encode the three parts. We are doing 3 operation, an addition, an XOR and a subtract.Īnd this the decoder, notice the inverse order:Īfter some trial and error encoding the file, I realized that I needed to encode the text, the rdata and the data section to avoid being detected. Shellcoding Linux x86 – Custom Crypter – Assignment 7įor this specific case, we don’t need a really complex encoder to bypass the AV, so we are going to keep the things simple. I’ve already wrote about a bit more complex topics during my SLAE exam, you can find the articles here: I’m going to use a really simple encoder because the purpose of this post is not to show you difficult encoding or encrypting techniques. This string can match an AV signature and our file can be detected, we should encode it. As an example, look at this string when I open the plain text binary in Olly: This specific binary has a big code cave and we don’t need to add more bytes with a PE and a hex editor, but I’m going to do it to modify the binary structure.Īfter doing this we need to encrypt or encode the binary to bypass the static scan. In the static scan the AV is going to look for strings that can match his signatures to try to identify the binary, also it can look for hashes or bytes length of the program. The AV is doing an static scan, and also a dynamic scan so we are going to need to bypass both. You can manage your security – from anywhere you can get online – and expert technical support is only a click away.In this blog post I’m going to show how to do a trick to bypass the Kaspersky 2018 AV.įor the example, I’m going to use a netcat 99 binary that Kaspersky is going to detect as the following by default: not-a-virus: It SIMPLIFIES – so you can get on with your busy life It PERFORMS – so security won't get in your wayīecause we've combined security & efficiency, you get protection that won't slow you down… so you can do more of the things you really want to do. That's why our cloud-assisted security does more to protect your PC from infections & ransomware – including WannaCry – and also helps you to avoid dangerous websites. If you're using Microsoft Windows XP, the product is not intended to operate on FAT32 file system.įeature It SECURES – with award-winning protectionĮvery day, hundreds of thousands of new malware items are unleashed – including ransomware that could lock up every file on your PC. Please visit /us/13746 to get more details. Some product features may not work on 64-bit operating systems. Product is not intended to operate on Windows 10 Mobile editions. If you're using Windows 10, you might need to download & install additional patches for your Kaspersky Lab security software (available after the product installation). If you're using Microsoft Internet Explorer 8, we cannot guarantee that the My Kaspersky portal and security management functions will operate correctly. Only final, officially released operating systems are supported by the product. Please note we do not support the beta versions/previews of new operating systems. Windows-based tablets (system with an Intel processor) Microsoft Windows XP Home / Professional (32-bit) SP3 or higher / Professional (64-bit) SP2 or higher Microsoft Windows Vista Home Basic / Home Premium / Business / Enterprise / Ultimate – SP2 or higher Microsoft Windows 7 Starter / Home Basic & Premium / Professional / Ultimate – SP0 or higher Microsoft Windows 8 & 8.1 / Pro / Enterprise / 8.1 update Microsoft Windows 10 Home / Pro / Enterprise System Requirements Internet connection required – for product activation & updates and for access to some features
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