pyload Log Injection vulnerability

Summary

A log injection vulnerability was identified in pyload. This vulnerability allows any unauthenticated actor to inject arbitrary messages into the logs gathered by pyload.

Details

pyload will generate a log entry when attempting to sign in with faulty credentials. This entry will be in the form of Login failed for user 'USERNAME'. However, when supplied with a username containing a newline, this newline is not properly escaped. Newlines are also the delimiter between log entries. This allows the attacker to inject new log entries into the log file.

PoC

Run pyload in the default configuration by running the following command

pyload

We can now sign in as the pyload user and view the logs at http://localhost:8000/logs.

Any unauthenticated attacker can now make the following request to inject arbitrary logs.

curl 'http://localhost:8000/login?next=http://localhost:8000/' -X POST -H 'Content-Type: application/x-www-form-urlencoded' --data-raw $'do=login&username=wrong\'%0a[2024-01-05 02:49:19]  HACKER               PinkDraconian  THIS ENTRY HAS BEEN INJECTED&password=wrong&submit=Login'

If we now were to look at the logs again, we see that the entry has successfully been injected.

Impact

Forged or otherwise, corrupted log files can be used to cover an attacker’s tracks or even to implicate another party in the commission of a malicious act.