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CVE-2015-3456 (VENOM) is a buffer overflow / out-of-bounds write vulnerability in QEMU's virtual Floppy Disk Controller (FDC), specifically in FIFO buffer handling while processing certain FDC commands. The issue is described as affecting commands including FD_CMD_READ_ID and FD_CMD_DRIVE_SPECIFICATION_COMMAND, as well as other unspecified commands. Because the vulnerable code is in an emulated device exposed to guest systems, a user inside a guest VM who can interact with the virtual floppy controller can trigger memory corruption in the host-side QEMU process. In environments using QEMU directly or via Xen/KVM integrations, this creates a guest-to-host escape condition.
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2 valid exploits after Mallory filtered fakes, detection scripts, and README-only repos (1 hidden).
This repository is a small, legitimate proof-of-concept for CVE-2015-3456 (VENOM) focused on reproducibly crashing vulnerable QEMU rather than escaping the VM or achieving host code execution. The core exploit is src/venom-crash.c, a guest-side C program that requests direct I/O access with ioperm(), writes the FDC READ_ID command (0x0a) to floppy controller data port 0x3f5, and then continuously floods that same port with byte 0x42. Its purpose is to drive the vulnerable floppy disk controller emulation code path until the host-side QEMU process crashes, producing a denial of service. Repository structure is straightforward: src/venom-crash.c contains the PoC; scripts/run-alpine.sh launches a vulnerable QEMU lab instance; scripts/run-alpine-gdb.sh launches the same environment under GDB for crash analysis; notes/setup.md documents how to build QEMU v2.3.0, create a floppy image, boot Alpine Linux, compile the guest PoC, and run it; logs/example-gdb-logs.log contains an example crash trace showing corrupted state and a crash in QEMU timer handling. The README explicitly states this is only a crash/DoS demonstrator and not a VM escape or host RCE exploit. The exploit does not contact remote network services or external C2 infrastructure. Its meaningful targets are local/virtualized resources: the guest-accessible FDC I/O port 0x3f5 and the vulnerable host QEMU process. The included scripts use QEMU user-mode networking (-net nic -net user), but networking is only for guest convenience and not part of the exploit path. Overall, this is a PoC-quality research repository intended to reproduce and analyze the VENOM crash condition in a controlled lab.
This repository is a set of experiments and tools related to CVE-2015-3456 (VENOM), a critical vulnerability in QEMU's virtual floppy disk controller (FDC) emulation. The repository is organized into three main directories: - `exploit/`: Contains a proof-of-concept C program (`exploit.c`) that triggers the vulnerability by sending repeated commands to the FDC I/O port (0x3f5), causing QEMU to crash. This is a denial-of-service exploit, not a full code execution exploit. - `mock/`: Provides a minimal, stripped-down version of QEMU with only the vulnerable FDC code, useful for testing and understanding the vulnerability in isolation. - `patch/`: Contains a live patching tool (`patch.c`) and a GDB script (`gdb-fix`) to patch a running QEMU process, mitigating the vulnerability by redirecting all FDC commands to a 'not implemented' handler. The patching tool works by attaching to the QEMU process via ptrace and modifying its memory directly, without requiring debug symbols or the original executable on disk. The exploit requires local access to the host running QEMU and sufficient privileges to access hardware I/O ports. The main exploit is a proof-of-concept that demonstrates the crash, while the patching tools provide a mitigation strategy. The repository is well-structured for research and educational purposes, illustrating both exploitation and live patching techniques for this vulnerability.
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