oleobj - Bug in filename extraction causing file overwrite

[malware-kitten]

When oleobj is run against a doc where the filenames can't be properly extracted, it's causing an output file to be overwritten.

Example run:

$ oleobj b2c07bb5ba4123dbd4ef3a3ff7d704c884fda5f59230a6d4913d1acd26e3b0b0.doc

Which produces the following output

oleobj 0.52.4 - http://decalage.info/oletools
THIS IS WORK IN PROGRESS - Check updates regularly!
Please report any issue at https://github.com/decalage2/oletools/issues

-------------------------------------------------------------------------------
File: 'b2c07bb5ba4123dbd4ef3a3ff7d704c884fda5f59230a6d4913d1acd26e3b0b0.doc'
extract file embedded in OLE object from stream 'ObjectPool/_1116929867/\x01Ole10Native':
Parsing OLE Package
Filename = "�#"
Source path = ""
Temp path = "("
saving to file b2c07bb5ba4123dbd4ef3a3ff7d704c884fda5f59230a6d4913d1acd26e3b0b0.doc___
WARNING  Wanted to read 4096, got 908
extract file embedded in OLE object from stream 'ObjectPool/_1130848458/\x01Ole10Native':
Parsing OLE Package
Filename = "�¾"
Source path = ""
Temp path = "("
saving to file b2c07bb5ba4123dbd4ef3a3ff7d704c884fda5f59230a6d4913d1acd26e3b0b0.doc___
WARNING  Wanted to read 4096, got 3596

And checking the contents of the directory after running oleobj

$ ls -l
total 152
-rw-r--r-- 1 user admin 104448 Jun 14 18:57 b2c07bb5ba4123dbd4ef3a3ff7d704c884fda5f59230a6d4913d1acd26e3b0b0.doc
-rw-r--r-- 1 user admin  48652 Jun 18  2018 b2c07bb5ba4123dbd4ef3a3ff7d704c884fda5f59230a6d4913d1acd26e3b0b0.doc___

Only the original sample and a single output file are displayed, where there should be 2 output files.

Just a suggestion, but if no filename could be found or no printable characters are found after sanitizing the filename just use the hash of the stream as an ID?

Unfortunately this is not in a shareable sample, but I hope this issue is enough to help tighten down on the bug.