The most secure and reliable way to obtain the file is through the Cisco Software Central portal.
Choose the c7200-adventerprisek9-mz.152-4.S2.bin file from your local machine when prompted. c7200adventerprisek9mz1524s2bin download new
The images available in CML may be the newer vios or iosv formats, but these are designed for modern virtualization and provide the same feature sets as the legacy IOS images. The most secure and reliable way to obtain