Stop further settling

The cracks are normally caused by settling of the building.The settling is commonly found around corners of buildings. In the most of cases, it's due to long standing water from the roof. 

The key thing is to stop further settling by building or maintaining rain gutters and downspouts. The downspouts need to be let out by an appropriate drainage system. Using some extension to the downspouts will also help lead the water away from the building.

The real test is to observe in raining weather and see if there is any standing water around the foundation.

Once the drainage issue is resolved, you can patch the cracks.

Based on the info above, this crack may not be a huge issue. You may just double check in the basement to make sure there is no other obvious crack or unleveled floor.

You may also use this as a bargain condition or ask the seller to order an engineering inspection as a contingency.