Description of problem:

tried to run /sbin/lastb to investigate a compromised system, and it seems it
was blank. got an selinux alert that SELinux is preventing /usr/sbin/sshd
(sshd_t) "append" to (var_log_t)

raw audit message:

avc: denied {append } for comm=sshd dev=dm-0 egid=0 euid=0 exe=/usr/bin/ssd
exit=-13 fsgid=0 fsuid=0 gid=0 items=0 name=btmp pid=13037
scontext=system_u:system_r:sshd_t:s0-s0:c0.c1023 sgid=0
subj=system_u;system_r:sshd_t:s0-s0:c0.c1023 suid=0 tclass=file
tcontext=unconfined_u:object_r:var_log_t:s0 tty=(none) uid=0