Leveraging the Security Audit Log (SAL)

Hi! Today I was reviewing some events generated for the Security Audit Log and noticed an interesting behavior.

For those who are not familiar with it, the Security Audit Log (SAL) allows SAP security administrators to keep track (via a log) of the activities performed in their SAP systems. In a future post we will discuss how to enable and configure this logging.

By default the SAL facility logs the “Terminal Name” which is either the Terminal Name (defined by the computer which performed the logged action) or the IP address of the computer that is the source of events. The IP address is only logged if the source computer does not transmit a Terminal Name with its communications.

This behavior can be abused by an attacker since filling the terminal name value in an RFC call is a task performed by the caller (the user’s machine). Having the ability to manipulate the “Terminal Name” means the attacker could try different attacks such as bruteforce attempts but have each transaction appear to come from a different terminal. Taken even further; the attacker could set an IP address (or cycle through a set of IP addresses) as the Terminal Name; meaning each request would appear to have originated from these IP addresses (as in the logs it is not possible to distinguish between an IP address that has been logged because no Terminal Name value was transmitted vs an IP addressed that has been logged as the Terminal Name).

Remediation

To fix this problem it is possible to configure the profile parameter “rsau/ip_only” and set it to 1. In this scenario whenever possible the source IP address of the event will be logged and the Terminal Name value is ignored. This change must be made to the profile file, it cannot be done using transaction RZ11.

For more information check the SAP note 1497445.

 

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