Under PA landlord tenant law is a landlord entitled to keep the security deposit in event of lease breach

You will likely need to ask a local attorney, as most states regulate a landlord's relationship to a tenant's security deposit by statute. Each state thus has different nuances regarding security deposits. However, your intuition is correct that the law protects security deposits as the tenant's property (even if under the control of the landlord) and a tenant may bring some type of a claim, based on local law, to recover their property.

It is important to tread lightly, as some locales provide specified damages such as attorney's fees and (in the case of Chicago) treble damages for a tenant harmed by an unaware landlord's actions. It is better to get good local advice before acting in security deposit matters.

If you don't wish to consult an attorney, a local tenant's union or tenant's pro bono organization may be able to assist you or at least direct you to the relevant laws.

NOTE: This answer is not intended to be legal advice and should not be construed in that way. This answer does not create an attorney-client relationship and no such relationship may be created absent a signed retainer agreement. The author is licensed in Illinois only, and his answer is for educational purposes alone.