  Dynamic searchable symmetric encryption (DSSE) enables a server to
efficiently search and update over encrypted files. To minimize the leakage
during updates, a security notion named forward and backward privacy is
expected for newly proposed DSSE schemes. Those schemes are generally
constructed in a way to break the linkability across search and update queries
to a given keyword. However, it remains underexplored whether forward and
backward private DSSE is resilient against practical leakage-abuse attacks
(LAAs), where an attacker attempts to recover query keywords from the leakage
passively collected during queries.
  In this paper, we aim to be the first to answer this question firmly through
two non-trivial efforts. First, we revisit the spectrum of forward and backward
private DSSE schemes over the past few years, and unveil some inherent
constructional limitations in most schemes. Those limitations allow attackers
to exploit query equality and establish a guaranteed linkage among different
(refreshed) query tokens surjective to a candidate keyword. Second, we refine
volumetric leakage profiles of updates and queries by associating each with a
specific operation. By further exploiting update volume and query response
volume, we demonstrate that all forward and backward private DSSE schemes can
leak the same volumetric information (e.g., insertion volume, deletion volume)
as those without such security guarantees. To testify our findings, we realize
two generic LAAs, i.e., frequency matching attack and volumetric inference
attack, and we evaluate them over various experimental settings in the dynamic
context. Finally, we call for new efficient schemes to protect query equality
and volumetric information across search and update queries.
