Insertion of Sensitive Information into Log File
Log injection in SimpleSAMLphp before version 1.18.4. The www/erroreport.php script, which receives error reports and sends them via email to the system administrator, did not properly sanitize the report identifier obtained from the request. This allows an attacker, under specific circumstances, to inject new log lines by manually crafting this report ID. When configured to use the file logging handler, SimpleSAMLphp will output all its logs by appending each log line to a given file. Since the reportID parameter received in a request sent to www/errorreport.php was not properly sanitized, it was possible to inject newline characters into it, effectively allowing a malicious user to inject new log lines with arbitrary content.
CWE-532 - Insertion of Sensitive Information into Log File
It's quite common for applications to save logs. For example, whenever a user requests a resource from a particular website, the web server writes information about the request to a log file. These files are helpful for identifying abnormal system activity, bugs, and evaluating the security controls of the application. Security of log files is critical for the overall security of the application and its confidential resources. An application that lacks appropriate logging levels can expose sensitive user data and system information stored on the log files to malicious users. This info can be exploited to compromise your system.