TLB is a binary support file that stores user interface data. TLB file format is used by applications that support OLE (Object Linking and Embedding) technology featured in Microsoft Visual Basic environment.

Windows users are vulnerable to a trojan malware stdole3, which saves itself in windows32 system folder and uses TLB files as its attack vector. The malware has been identified in 2006 and now most antivirus software recognize this threat and deal with it accordingly.