![]() ![]() If you've got any questions feel free to pop me a message on Twitter or e-mail. However, this year I attempted to make the challenges a bit easier to capture the interest of contestants that were new to the field. Last year I also wrote the reverse engineering challenges which were used, so built on the feedback that I received. This year for ENUSEC's LTDH ( "Le Tour Du Hack") I was tasked with writing the reverse engineering challenges needed for the CTF aspect of the event. NET we've got dnlib, and for Java, we have ASM.Ĭomprehensive walkthrough of the LTDH19 RE challenges This is easier to achieve when managed code is involved as they're typically much more comfortable to manipulate, for. To get around this, you can create your own tooling to deobfuscate binaries and strip them of these circumventions automatically. MainService may become OQuXiqmXq throughout the code). This can be done in several ways and may include control flow obfuscation (making the flow of the program confusing, random jumps.), string obfuscation (not having text in plain sight, may be encrypted, encoded.), junk code (pointless code which does nothing, merely a way to confuse analysts), object renaming (renaming objects within the code from their original, e.g. When a threat actor wishes to circumvent analysis from a reverse engineering standpoint, a common technique utilised by the attackers is to obfuscate their malicious code. ![]() Writing a simple deobfuscator for a simple C# malware variant We can trivially disable this DLL, by replacing it with our own or simply unloading it from the process. This quick blog post highlights some of the flaws found in the Zoom application when attempting to do integrity checking, these checks verify that the DLLs inside the folder are signed by Zoom and also that no 3rd party DLLs are loaded at runtime. Tampering with Zoom's Anti-Tampering Library It involves executing the target binary with various input values generated by the fuzzer, to test the program - the goal is to get it to crash. Fuzzing is a common method for finding vulnerabilities in software, in particular memory management vulnerabilities. If we were to find a parsing bug in YARA, it could possibly lead to code execution if a victim ( in this case) runs our specially crafted executable through it. We'll be using the excellent american fuzzy lop ( a.k.a. Whilst I didn’t manage to crash YARA when following the methodology that this post outlines whilst targeting the PE module – it'd be great to hear recommendations on how the process I followed upon could be improved on that I’ve made in my YARA fuzzing venture. I've always been interested in fuzzing YARA to see if anything interesting would be produced. wsb was not inspected or blacklisted on any major EDR or AV. ![]() With this technique in terms of executing within a VM, we don't need to load an external ISO onto the machine, as all of this is handled by the sandbox. This short blog post may be useful for a Red Team by living-of-the-land for the execution of payloads on a machine where Windows Sandbox can be enabled Windows Sandbox is designed to work this way - no exploitation of anything is covered in this post. ![]() I've not posted on here since May, as I've been busy with (well, life in general) projects and whatnot. Weaponizing Windows Sandbox To Bypass Defender Stealthy Process Communication Between Threads on Windows 10 System Guard Runtime Monitor (SGRM) is a component of Windows Defender (WD), that was introduced in the Windupdate and has been present since as a key component to ensure system integrity. What is System Guard Runtime Monitor? (SGRM) Inside Windows Defender System Guard Runtime Monitor Greg Lesnewich published a partial version of a Export Hash using YARA, which took into account the whole table. They may have a partial Export Address Table compromising of a dozen functions that exist in the legitimate equivalent, or simply the target function they wish to invoke. Tracking DLLs which are used in search-order hijacking can sometimes be tricky. Introducing Exphash: Identifying Malicious DLLs With Export HashingĮxport Hashing (”exphash”), inspired by Mandiant’s imphash, is a SHA-256 hash of ordinal-ordered export names in PEs. ![]()
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