You can achieve that using multiple linear gradients as a background image.
div {
width: 100px;
height: 100px;
background:
linear-gradient(to right, black 4px, transparent 4px) 0 0,
linear-gradient(to right, black 4px, transparent 4px) 0 100%,
linear-gradient(to left, black 4px, transparent 4px) 100% 0,
linear-gradient(to left, black 4px, transparent 4px) 100% 100%,
linear-gradient(to bottom, black 4px, transparent 4px) 0 0,
linear-gradient(to bottom, black 4px, transparent 4px) 100% 0,
linear-gradient(to top, black 4px, transparent 4px) 0 100%,
linear-gradient(to top, black 4px, transparent 4px) 100% 100%;
background-repeat: no-repeat;
background-size: 20px 20px;
}
<div></div>