Summary
Rack::CommonLogger can be exploited by crafting input that includes newline characters to manipulate log entries. The supplied proof-of-concept demonstrates injecting malicious content into logs.
Details
When a user provides the authorization credentials via Rack::Auth::Basic, if success, the username will be put in env['REMOTE_USER'] and later be used by Rack::CommonLogger for logging purposes.
The issue occurs when a server intentionally or unintentionally allows a user creation with the username contain CRLF and white space characters, or the server just want to log every login attempts. If an attacker enters a username with CRLF character, the logger will log the malicious username with CRLF characters into the logfile.
Impact
Attackers can break log formats or insert fraudulent entries, potentially obscuring real activity or injecting malicious data into log files.
Mitigation
- Update to the latest version of Rack.
HexSave Reporter
jeremyevans Remediation developer
ioquatix Coordinator
Summary
Rack::CommonLoggercan be exploited by crafting input that includes newline characters to manipulate log entries. The supplied proof-of-concept demonstrates injecting malicious content into logs.Details
When a user provides the authorization credentials via
Rack::Auth::Basic, if success, the username will be put inenv['REMOTE_USER']and later be used byRack::CommonLoggerfor logging purposes.The issue occurs when a server intentionally or unintentionally allows a user creation with the username contain CRLF and white space characters, or the server just want to log every login attempts. If an attacker enters a username with CRLF character, the logger will log the malicious username with CRLF characters into the logfile.
Impact
Attackers can break log formats or insert fraudulent entries, potentially obscuring real activity or injecting malicious data into log files.
Mitigation