CVE-2020-8835 PoC — Linux kernel bpf verifier vulnerability

Source

https://github.com/johnatag/INF8602-CVE-2020-8835

Associated Vulnerability

Title:Linux kernel bpf verifier vulnerability (CVE-2020-8835)
Description:In the Linux kernel 5.5.0 and newer, the bpf verifier (kernel/bpf/verifier.c) did not properly restrict the register bounds for 32-bit operations, leading to out-of-bounds reads and writes in kernel memory. The vulnerability also affects the Linux 5.4 stable series, starting with v5.4.7, as the introducing commit was backported to that branch. This vulnerability was fixed in 5.6.1, 5.5.14, and 5.4.29. (issue is aka ZDI-CAN-10780)

Readme

# INF8602-CVE-2020-8835
## Testing the kernel exploit

1. Testing without Docker
```bash
cd ../app
npm i
node server.js
```

2. Testing with Docker to test defensive capability
```bash
# Make sure to be in the same directory as the Dockerfile
# Build the Docker image
docker build . -t inf8602/node-web-app
# Your docker image should be listed by Docker
docker images
# Run the image
docker run -p 8080:8080 -d inf8602/node-web-app
# Print the output of the app
docker ps #get the container id
docker logs <container id> # print app output
# Example
# Hello World
```

3. Testing the fix (disabling priviledge bpf)
```bash
sudo sysctl kernel.unprivileged_bpf_disabled=1
cd ../app
npm i
node server.js
```

4. Testing with Dev containers
```
Open in Container
```

File Snapshot

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