flux@0xfluxsec
As I teased earlier - I used Claude Code to (near enough) autonomously develop an exploit for a known vulnerable driver. Claude did it with no hesitation - from triage to exploit. As you can see, it was successful in privilege escalation. Read what I found below!
This is a long read - but I hope you find it useful and an interesting topic to debate.
As a background, through the last week I used GPT-5.4 to analyse a known vulnerable driver to identify any opportunities to exploit. I have already documented my process in detail (check my recent posts for context if you wish) - in short I connected it to an MCP in IDA Pro for GPT to find the vulnerability. It did it. I then asked it to develop an exploit but it refused, I had to write an exploit myself which I did, as a POC that it had found the vuln.
The vulnerability in question is an arbitrary physical memory read & memory write - a super critical bug. There was one limiting factor to this, the driver was limited to only 32-bits of physical address, which covers up to 4 GB of physical RAM. On modern systems with 8+ GB RAM, EPROCESS structures for important processes (including System, PID 4) are typically allocated well above the 4 GiB boundary. The driver simply cannot address them. This is also where my knowledge starts breaking down; I'm not a well versed kernel exploit dev and there is always more to learn with low level security. So, I'm going to quote Claude here:
But VirtualAlloc + VirtualLock has a key property: the physical pages backing locked user-space memory are guaranteed to be resident (non-pageable), and on x64 Windows with typical RAM configurations, user-mode allocations frequently land in low physical memory because the user-mode VA range starts from the bottom of the address space, and early allocations map to low physical pages.
More precisely: you don't need the physical address to be below 4 GiB for EPROCESS — you need the payload to be below 4 GiB. The write primitive lets you write from a physical address into a kernel VA.
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To the point before we return to Claude, I asked Claude to exploit the driver. Recall GPT refused.. well.. Claude to my (un)surprise, did not! Fantastic! For context I purchased the £20 p/m plan, and had to buy extra tokens also.
So, off it went - I had to go back and forth over the course of several days to get the exploit working as 3 prompts.. YES THREE PROMPTS.. was enough to hit my cap.........!? But that aside, I did not have to guide it, only pass it what the console printed in my VM and the occasional crash dump when I hit a Blue Screen.
Many iterations and £40 later, I tested it (this morning) and VIOLA, it managed to exploit the driver to get NT AUTHORITY\SYSTEM, the highest privilege level available in user mode.
So back to the technical topic, as mentioned, the difficulty was that we only had a 32-bit register to use in order to overwrite critical structures in memory to elevate our privilege. Claude came up with the following strategy:
1. VirtualAlloc + VirtualLock a page in your own process — this pins it in physical RAM
2. Write your payload (the SYSTEM token value) into that page
3. Find the physical address of that page by scanning physical RAM for a sentinel you wrote alongside the payload
4. Use the write primitive: memmove(target_kernel_va, your_physical_page, 8) — this copies 8 bytes from your user page's physical address into the kernel VA of the target's EPROCESS.Token
The user-mode page is virtually always sub-4GiB in physical address because Windows allocates low physical pages to user processes first (high memory is preferred for kernel use). Even if it weren't guaranteed, you'd just retry until you get a sub-4GiB physical page.
One critical safety measure: you must exclude MMIO regions from the scan. Certain physical address ranges are memory-mapped I/O — reading them via MmMapIoSpace can trigger hardware side effects or cause an IRQL_NOT_LESS_OR_EQUAL BSOD. The registry CM_RESOURCE_LIST gives you the actual RAM ranges, so you scan only those. Early iterations that scanned the full 4 GiB range BSODed immediately upon hitting MMIO.
I will include some screenshots in this post showing its thought process.
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On to the code that it wrote, I (of course) asked it to write the exploit in Rust. Now, the code it wrote is 923 lines, kinda gross, lots of sweeping unsafe code, but I cannot fault the results. It provided good comments, descriptive code, and good problem solving.
I don't really have much else to say on this point, good robot.
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Now, this driver was abused by ransomware gangs for spreading their ransomware by elevating privilege and executing arbitrary code. Thankfully now - this driver is on the blocklist so I don't mind sharing the POC (I will leave a link in the comments to the code it created). For my own ethical sanity, from the horses mouth: "These vulnerabilities have been patched by both Paragon Software, and vulnerable BioNTdrv.sys versions blocked by Microsoft's Vulnerable Driver Blocklist".
The implication of this is, in my opinion, massive. Ransomware gangs, hacktivists, nation states, now have the power to develop exploits at scale, with a lower barrier to entry to conduct their activity. So, that leads to the question - should companies such as OpenAI / Anthropic with their ChatGPT and Claude models restrict this? In my opinion - no. I think more good can come of it than bad - there are far more good people in the world who are trying to make things more secure, and with the advent of researchers and programmers using these tools to find and disclose vulnerabilities ethically, gives more credence to them being fixed and security tools & vendors being on top of the game.
Adversaries are always going to have local LLMs as the tech evolves that is unrestricted - so the leading companies in this space should adopt and be ahead of the curve, giving researchers and devs the same power as the adversary.
Also, as a fun idea, it could push people towards memory safe languages such as Rust which are significantly less prone to memory bugs that often allow remote code execution. Note that in this case, Rust would not have prevented this vulnerability, as it comes from a bad driver implementation, rather than a strict memory safety issue.
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If you made it this far, thanks for reading, this turned out longer than expected and I may move it over to a blog post! I am working on a tool to automate this process at scale (more the discovery of vulnerabilities) so, make sure to follow me if you want to check in with the progress of that project!
Remember - SECURE BOOT: ON, HVCI: ON, and known vulnerable driver blocklist: ON!
