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.
References: