Hiding Information into OOXML Documents: New Steganographic Perspectives

Aniello Castiglione¹⁺, Bonaventura D'Alessio¹, Alfredo De Santis¹, and Francesco Palmieri²

¹Dipartimento di Informatica

University of Salerno

Salerno, Italy
{castiglione,bdalessio,ads}@dia.unisa.it

²Dipartimento di Ingegneria dell'Informazione

Second University of Naples

Aversa (CE), Italy
francesco.palmieri@unina.it

Abstract

The simplest container of digital information is "the file" and among the vast array of files currently

available, MS-Office files are probably the most widely used. The "Microsoft Compound Document

File Format" (MCDFF) has often been used to host secret information. The new format created

by Microsoft, first used with MS-Office 2007, makes use of a new standard, the "Office Open

XML Formats" (OOXML). The benefits include that the new format introduces the OOXML format,

which lowers the risk of information leakage, as well as the use of MS-Office files as containers for

steganography.

In this work the authors, starting from the classification of information hiding adapted from Bauer,

analyze four new methods for embedding data into the OOXML file format. These methods can

be extremely useful when using MS-Office documents for steganographic purposes. The authors,

analyzing a scenario composed of about 50.000 MS-Office files, highlight how the proposed methods

are really helpful in real applications. An evaluation of the limits of the proposed methods is carried

out by comparing them against the tool introduced by Microsoft to sanitize MS-Office files. The

methods presented can be combined in order to extend the amount of data to be hidden in a single

cover file.

Keywords: Steganography, OOXML format, stegosystem, document steganography, microsoft office

document, information hiding.

+Corresponding author: Aniello Castiglione,
B Dipartimento di Informatica - Università degli Studi di Salerno, Via Ponte don Melillo, I-84084 Fisciano (SA), Italy.

Tel: +39089969594, Email: castiglione@ieee.org, castiglione@acm.org

Journal of Wireless Mobile Networks, Ubiquitous Computing, and Dependable Applications (JoWUA),

Vol. 2, No. 4, pp. 59-83, December 2011 [pdf]