pdf news pdf spam

PDF Spam Back With a Vengeance

Because of the malware now hidden in the attachment, this round of PDF spam is significantly more malicious than the flood that hit in August.
Cara Garretson, Network World

PDF spam, the summertime nuisance that flooded inboxes in early August and then quickly disappeared, is back and worse than ever.

According to multiple threat researchers at security vendors, tens of thousands of spam messages were blasted out last week with attached PDF files, which infect the recipients' PCs when viewed. The subject lines of the new crop of PDF spam are finance-related, according to security vendors, using phrases designed to get the recipient's attention such as "your credit report." These e-mails contain no text, simply the attachment.

"When opened, the PDF file uses the CVE-2007-5020 vulnerability via Acrobat Reader and [Internet Explorer 7.0] and downloads further malware from a server in Malaysia," according to security vendor F-Secure's recent blog post. "The target of the malware seems to be to create a botnet of infected machines to be used for further malicious activity."

This summer's PDF spam raised eyebrows because of the sheer volume of the messages and the creative thinking on the part of spammers who figured out these messages could circumvent most antispam filters because they're not trained to read PDF attachments.

Because of the malware now hidden in the attachment, this round of PDF spam is significantly more malicious than August's blasts that were typically pump-and-dump stock messages.

The PDFs attached to those messages hid no malware, but attempted to persuade recipients to buy penny stocks in a little-known company so the stock price would be driven up and the spammer could sell at a profit.

While PDF spam disappeared by September as quickly as it arrived -- it went from 30% of all spam sent on Aug. 7 to less than 1% on Aug. 29 -- few security professionals are expressing surprise at its return.

Spammers will "exploit any vulnerabilities they can, which in Windows is about a quadrillion different places," says John Levine [stet], president of consulting firm Taughannock Networks and co-chair of the Internet Engineering Task Force's Anti-Spam Research Group, adding that he believes this PDF spam blast to be the latest incarnation of the Storm malware. "Using Acrobat has the added advantage that it works regardless of what mail program you use, so even people who use Eudora or Thunderbird could get bitten."

Adobe on Oct. 22 released a security update for versions 8.1 and earlier of Adobe Reader and Acrobat

pdf news pdf spam
source : http://www.pcworld.com/article/id,139191-c,spam/article.html

pdf portable document format

From Wikipedia, the free encyclopedia

Portable Document Format (PDF)

"PDF" redirects here. For other uses, see PDF (disambiguation).

The Portable Document Format (PDF) is the file format created by Adobe Systems in 1993 for document exchange. PDF is used for representing two-dimensional documents in a device-independent and display resolution-independent fixed-layout document format. Each PDF file encapsulates a complete description of a 2-D document (and, with Acrobat 3-D, embedded 3-D documents) that includes the text, fonts, images, and 2-D vector graphics that compose the document.

PDF is an open standard, and is now being prepared for submission as an ISO standard

History
When the PDF first came out in the early 1990s, its general adoption was slow. At that time, the PDF-creation tools (Acrobat) and the viewing and printing software had to be bought. Early versions of PDF had no support for external hyperlinks, reducing its usefulness on the World Wide Web; the additional size of the PDF document compared to plain text meant significantly longer download times over the slower modems common at the time, and rendering the files was slow on less powerful machines. Additionally, there were competing formats such as Envoy, Common Ground Digital Paper and even Adobe's own PostScript format (.ps); in those early years, the PDF file was mainly popular in desktop publishing workflow.

Adobe soon started distribution at no cost of the Acrobat Reader (now Adobe Reader) program, and continued supporting the original PDF, which eventually became the de facto standard for printable documents.

The PDF file format has changed several times, as new versions of Adobe Acrobat have been released. There have been eight versions of PDF: 1.0 (1993), 1.1 (1994), 1.2 (1996), 1.3 (1999), 1.4 (2001), 1.5 (2003), 1.6 (2005), and 1.7 (2006), corresponding to Acrobat releases 1.0 to 8.0.

See also History of PDF Openness

Technical Foundations
Anyone may create applications that read and write PDF files without having to pay royalties to Adobe Systems; Adobe holds patents to PDF, but licenses them for royalty-free use in developing software complying with its PDF specification.

The PDF combines three technologies:


A sub-set of the PostScript page description programming language, for generating the layout and graphics.
A font-embedding/replacement system to allow fonts to travel with the documents.
A structured storage system to bundle these elements and any associated content into a single file, with data compression where appropriate.

PostScript
PostScript is a page description language run in an interpreter to generate an image, a process requiring many resources. PDF is a file format, not a programming language, i.e. flow control commands such as if and loop are removed, while graphics commands such as lineto remain.

Often, the PostScript-like PDF code is generated from a source PostScript file. The graphics commands that are output by the PostScript code are collected and tokenized; any files, graphics, or fonts to which the document refers also are collected; then, everything is compressed to a single file. Therefore, the entire PostScript world (fonts, layout, measurements) remains intact.

As a document format, PDF has several advantages over PostScript:

PDF contains already tokenized and interpreted results of the PostScript source code, for direct correspondence between changes to items in the PDF page description and changes to the resulting page appearance.

PDF (from version 1.4) supports true graphic transparency, PostScript does not.
PostScript is an imperative programming language (with an implicit global state), so instructions accompanying the description of one page can affect the appearance of any following page. Therefore, all preceding pages must be processed in order to determine the correct appearance of a given page; each page in a PDF document is unaffected by the others.

Technical Overview
File Structure

A PDF file consists primarily of objects, of which there are eight types:[4]
Boolean values, representing true or false
Numbers
Strings
Names
Arrays, ordered collections of objects
Dictionaries, collections of objects indexed by Names
Streams, usually containg large amounts of data.
The null object

Objects may be either direct (embedded in another object) or indirect. Indirect objects are numbered with an object number and a generation number. An index table called the xref table gives the byte offset of each indirect object from the start of the file.[5] This design allows for efficient random access to the objects in the file, and also allows for small changes to be made without rewriting the entire file (incremental update).

Beginning with PDF version 1.5, indirect objects may also be located in special streams known as object streams. This technique reduces the size of files that have large numbers of small indirect objects and is especially useful for Tagged PDF.

Imaging Model
The basic design of how graphics are represented in PDF is very similar to that of PostScript, except for the use of transparency, which was added in PDF 1.4.
PDF graphics use a device independent Cartesian coordinate system to describe the surface of a page. A PDF page description can use a matrix to scale, rotate, or skew graphical elements. A key concept in PDF is that of the graphics state, which is a collection of graphical parameters that may be changed, saved, and restored by a page description. PDF has (as of version 1.6) 24 graphics state properties, of which some of the most important are:

The current transformation matrix (CTM) which determines the coordinate system
The clipping path
The color space
The alpha constant which is a key component of transparency

Vector Graphics
Vector graphics in PDF, as in PostScript, are constructed with paths. Paths are usually made from of lines and cubic Bezier curves, but can also be constructed from the outlines of text. Unlike PostScript, PDF does not allow a single path to mix text outlines with lines and curves. Paths can be stroked, filled, or used for clipping. Strokes and fills can use any color set in the graphics state, including patterns.

PDF supports several types of patterns. The simplest is the tiling pattern in which a piece of artwork is specified to be drawn repeatedly. This may a colored tiling pattern, with the colors specified in the pattern object, or an uncolored tiling pattern, which defers color specification to the time the pattern is drawn. Beginning with PDF 1.4 there is also a shading pattern which draws continuously varying colors. There are seven types of shading pattern of which the simplest are the radial shade (Type 2) and axial shade (Type 3).


Raster Images
Raster images in PDF (called Image XObjects) are represented by dictionaries with an associated stream. The dictionary described properties of the image, and the stream contains the image data. (Less commonly, a raster image may be embedded directly in a page description as an inline image.) Images are typically filtered for compression purposes. Image filters supported in PDF include the general purpose filters


ASCII85Decode a deprecated filter used to put the stream into 7-bit ASCII
ASCIIHexDecode similar to ASCII85Decode but less compact
FlateDecode a commonly used filter based on the DEFLATE or Zip algorithm
LZWDecode a deprecated filter based on LZW Compression
RunLengthDecode a simple compression method for streams with repetitive data using the Run-length encoding algorithm
and the image-specific filters

Normally all image content in a PDF is embedded in the file. But PDF allows image data to be stored in external files by the use of external streams or Alternate Images. Standardized subsets of PDF, including PDF/A and PDF/X, prohibit these techniques.

Text
Text in PDF is represented by text elements in page content streams. A text element specifies that characters in should be drawn at certain positions. The characters are specified using the encoding of a selected font resource.

Fonts
A font object in PDF is a description of a digital typeface. It may either describe the characteristics of a typeface, or it may include an embedded font file. The latter case is called an embedded font while the former is called an unembedded font. The font files that may be embedded are based on widely used standard digital font formats: Type 1 (and its compressed variant CFF), TrueType, and (beginning with PDF 1.6) OpenType. Additionally PDF supports the Type 3 variant in which the components of the font are described by PDF graphic operators.

Encodings
Within text strings characters are shown using character codes (integers) that map to glyphs in the current font using an encoding. There are a number of built-in encodings, including WinAnsi, MacRoman, and a large number of encodings for East Asian languages. (Although the WinAnsi and MacRoman encodings are derived from the historical properties of the Windows and Macintosh operating systems, fonts using these encodings work equally well on any platform.) The encoding mechanisms in PDF were designed for Type 1 fonts, and the rules for applying them to TrueType fonts are complex.
For large fonts or fonts with non-standard glyphs, the special encodings Identity-H (for horizontal writing) and Identity-V (for vertical) are used. With such fonts it is necessary to provide a ToUnicode table if semantic information about the characters is to be preserved.

Transparency
The original imaging model of PDF was, like PostScript's, opaque: each object drawn on the page completely replaced anything previously marked in the same location. In PDF 1.4 the imaging model was extended to allow transparency. When transparency is used, new objects interact with previously marked objects to produce blending effects. The addition of transparency to PDF was done by means of new extensions that were designed to be ignored in products written to the PDF 1.3 and earlier specifications. As a result, files that use a small amount of transparency might view acceptably in older viewers, but files making extensive use of transparency could view completely wrong in an older viewer without warning.
The transparency extensions are based on the key concepts of transparency groups, blending modes, shape, and alpha. The model is closely aligned with the features of Adobe Illustrator version 9. The blend modes were based on those used by Adobe Photoshop at the time. When the PDF 1.4 specification was published the formulas for calculating blend modes were kept secret by Adobe. They have since been published.[6]

Technical Issues

source : http://en.wikipedia.org/wiki/Portable_Document_Format

pdf adobe acrobat history

Wisdom of the PDF Sage
Leonard Rosenthol’s thoughts on all things PDF




History of PDF Openness

I thought I would put together a bit of a timeline that covers the history of PDF as an open/published standard, both from Adobe as well as from ISO. After I put that together, I thought it would be interesting to include dates for key open source and other independent implementations of PDF, so I’ve added those as well.

















Leonard Rosenthol is the Technical Standards Evangelist for Adobe Systems that focuses on PDF Standards. In this role, he serves as technical expert for the U.S. delegation to ISO TC171 and TC130

PDF Timeline

1993
June: Adobe publishes the original PDF Reference (as a printed book by Addison Wesley) following the release of Acrobat 1.0

1994
October: Ghostscript 3.20 (beta) “contains some support for a PDF interpreter”
November: Adobe publishes PDF Reference 1.1

1995
January: Ghostscript 3.23 (beta) is the first release to include “a largely working PDF reader”
June: CGATS hosts the first meeting to discuss the use of PDF for prepress exchange, what will become PDF/X.
December: First public release of Xpdf

1996
November: Adobe publishes PDF Reference 1.2

1997
September: First public release of PDFlib

1998
December: First public release of iText

1999
April: Adobe publishes PDF Reference 1.3
November: PDF/X-1 becomes an ANSI standard

2000
March: First meeting of ISO TC130 for PDF/X
September: Submission of PDF/X-3 to ISO
September: Apple releases Mac OS X Public Beta

2001
April: Adobe publishes PDF Reference 1.4
April: ISO 15930-1 (PDF/X-1a) is adopted

2002
September: ISO 15930-3 (PDF/X-3) is adopted
October: AIIM hosts the first meeting to discuss the use of PDF for long term archival storage, what will become PDF/A.

2003
May: Adobe publishes PDF Reference 1.5
October: First meeting of ISO TC171 for PDF/A

2004
March: AIIM hosts the first meeting to discuss the use of PDF for use in engineering workflows, what will become PDF/E
December: Adobe publishes PDF Reference 1.6

2005
January: First meeting of AIIM working group for PDF/UA (Universal Accessibility)
June: First ISO meeting for PDF/E
October: ISO 19005-1 (PDF/A) is adopted

2006
October: Adobe publishes PDF Reference 1.7

2007
January: Adobe announces their intent to submit PDF 1.7 to ISO

Other PDF History Links
Adobe’s PDF History site (which has a neat graphic timeline on it)
Interesting 3rd party view of PDF/Acrobat history


pdf adobe acrobat history
source : http://www.acrobatusers.com/blogs/leonardr/history-of-pdf-openness/

pdf text

This chapter describes the special facilities in PDF for dealing with text— specifically, for representing characters with glyphs from fonts. A glyph is a graphical shape and is subject to all graphical manipulations, such as coordinate transformation. Because of the importance of text in most page descriptions, PDF provides higher-level facilities that permit an application to describe, select, and render glyphs conveniently and efficiently.

The first section is a general description of how glyphs from fonts are painted on the page. Subsequent sections cover the following topics in detail:

•Text state. A subset of the graphics state parameters pertain to text, including parameters that select the font, scale the glyphs to an appropriate size, and accomplish other graphical effects.

•Text objects and operators. The text operators specify the glyphs to be painted, represented by string objects whose values are interpreted as sequences of character codes. A text object encloses a sequence of text operators and associated parameters.

•Font data structures. Font dictionaries and associated data structures provide information that a consumer application needs to interpret the text and position the glyphs properly. The definitions of the glyphs themselves are contained in font programs, which may be embedded in the PDF file, built into the application, or obtained from an external font file.

full pdf text
PDF Reference, Sixth Edition, version 1.7 (PDF, 31.0M)

pdf graphics

The graphics operators used in PDF content streams describe the appearance of pages that are to be reproduced on a raster output device. The facilities described in this chapter are intended for both printer and display applications.

The pdf graphics operators form six main groups:

•PDF Graphics state operators manipulate the data structure called the graphics state, the global framework within which the other graphics operators execute. The graphics state includes the current transformation matrix (CTM), which maps user space coordinates used within a PDF content stream into output device coordinates. It also includes the current color, the current clipping path, and many other parameters that are implicit operands of the painting operators.

•Path construction operators specify paths, which define shapes, line trajectories, and regions of various sorts. They include operators for beginning a new path, adding line segments and curves to it, and closing it.

•Path-painting operators fill a path with a color, paint a stroke along it, or use it as a clipping boundary.

•Other painting operators paint certain self-describing graphics objects. These include sampled images, geometrically defined shadings, and entire content streams that in turn contain sequences of graphics operators.

•Text operators select and show character glyphs from fonts (descriptions of typefaces for representing text characters). Because PDF treats glyphs as general graphical shapes, many of the text operators could be grouped with the graphics state or painting operators. However, the data structures and mechanisms for dealing with glyph and font descriptions are sufficiently specialized that Chapter 5 focuses on them.

•Marked-content operators associate higher-level logical information with objects in the content stream. This information does not affect the rendered appearance of the content (although it may determine if the content should be presented at all; see Section 4.10, "Optional Content"); it is useful to applications that use PDF for document interchange. Marked content is described in Section 10.5, "Marked Content."

This chapter presents general information about device-independent graphics in PDF: how a PDF content stream describes the abstract appearance of a page. Rendering—the device-dependent part of graphics—is covered in Chapter 6. The Bibliography lists a number of books that give details of these computer graphics concepts and their implementation.


full pdf graphics
PDF Reference, Sixth Edition, version 1.7 (PDF, 31.0M)

pdf syntax

This chapter covers everything about the syntax of PDF at the object, file, and document level. It sets the stage for subsequent chapters, which describe how the contents of a PDF file are interpreted as page descriptions, interactive navigational aids, and application-level logical structure.

PDF syntax is best understood by thinking of it in four parts, as shown in Figure 3.1:

•Objects. A PDF document is a data structure composed from a small set of basic types of data objects. Section 3.1, "Lexical Conventions," describes the character set used to write objects and other syntactic elements. Section 3.2, "Objects," describes the syntax and essential properties of the objects. Section 3.2.7, "Stream Objects," provides complete details of the most complex data type, the stream object.

•File structure. The PDF file structure determines how objects are stored in a PDF file, how they are accessed, and how they are updated. This structure is independent of the semantics of the objects. Section 3.4, "File Structure," describes the file structure. Section 3.5, "Encryption," describes a file-level mechanism for protecting a document’s contents from unauthorized access.

•Document structure. The PDF document structure specifies how the basic object types are used to represent components of a PDF document: pages, fonts, annotations, and so forth. Section 3.6, "Document Structure," describes the overall document structure; later chapters address the detailed semantics of the components.

•Content streams. A PDF content stream contains a sequence of instructions describing the appearance of a page or other graphical entity. These instructions, while also represented as objects, are conceptually distinct from the objects that represent the document structure and are described separately. Section 3.7, "Content Streams and Resources," discusses PDF content streams and their associated resources.

full pdf syntax
PDF Reference, Sixth Edition, version 1.7 (PDF, 31.0M)

pdf overview

PDF is a file format for representing documents in a manner independent of the application software, hardware, and operating system used to create them and of the output device on which they are to be displayed or printed. A PDF documentconsists of a collection of objects that together describe the appearance of one or more pages, possibly accompanied by additional interactive elements and higher-level application data. A PDF file contains the objects making up a PDF document along with associated structural information, all represented as a single self-contained sequence of bytes.


A document’s pages (and other visual elements) can contain any combination of text, graphics, and images. A page’s appearance is described by a PDF content stream, which contains a sequence of graphics objects to be painted on the page. This appearance is fully specified; all layout and formatting decisions have already been made by the application generating the content stream.



In addition to describing the static appearance of pages, a PDF document can contain interactive elements that are possible only in an electronic representation. PDF supports annotations of many kinds for such things as text notes, hypertext links, markup, file attachments, sounds, and movies. A document can define its own user interface; keyboard and mouse input can trigger actions that are specified by PDF objects. The document can contain interactive form fields to be filled in by the user, and can export the values of these fields to or import them from other applications.


Finally, a PDF document can contain higher-level information that is useful for interchange of content among applications. In addition to specifying appearance, a document’s content can include identification and logical structure information that allows it to be searched, edited, or extracted for reuse elsewhere. PDF is particularly well suited for representing a document as it moves through successive stages of a prepress production workflow.

full pdf overview
PDF Reference, Sixth Edition, version 1.7 (PDF, 31.0M)