Detailed investigations of both endogenic and exogenic dark-haloed craters can provide critical information concerning the geology, composition, and evolution of portions of the lunar surface. Several dark-haloed and dark-rayed craters have been identified in the Maurolycus region in the southeastern nearside highlands. Clementine and Galileo multispectral imagery as well as Earth-based remote-sensing data were used to investigate the composition and origin of dark-haloed craters in the region. A striking albedo anomaly is associated with Buch B crater, which exhibits both a dark halo and dark rays. The result of a morphologic analysis clearly indicated that Buch B is an impact structure, not a volcanic vent. The optical maturity image shows that the Buch B ejecta deposits are immature and the radar and thermal data indicate a high abundance of fresh rocks and fragments in the 1--50 cm size range. FeO and TiO2 data as well as five point spectra extracted from Clementine UV-VIS images indicate that the dark ejecta is composed of immature mare-like material and may contain minor amounts of highland debris. Buch B excavated either an isolated cryptomare or, more likely, a mafic intrusion. One or more dikes of basaltic composition are possible candidates. Minor low-albedo anomalies have been identified around three other impact craters (Maurolycus A and B and Barocius M) in the region. While small FeO enhancements are seen in portions of the ejecta deposits associated with these craters, they do not approach the FeO values (12--14 wt.%) exhibited by the dark deposits of Buch B, and they do fall within the range of FeO abundances (5--9 wt.%) exhibited by highland terrain in the Maurolycus region. Hence the presence of a basaltic component is not required, and it cannot be concluded that either cryptomare or mafic intrusions were present in the target sites of these craters.