Figure xref and trailer. We can see that there are 14 objects in the xref table. We could go on and try to decode other sections as well, but this is out of the scope of this article. We must know by now that all PDF documents should be read from the end to the start. The trailer is represented in the picture below:. Figure Object We can see that the object is indeed the Document Catalog. The Page Tree object with an ID is represented in the picture below:.
Figure Page Tree object. So the object contains the actual pages of the PDF document. It contains 10 pages, which is exactly right we can check this out if we open the PDF file with any PDF reader and check the number of pages. We know that the Kids attribute specifies all the child elements directly accessible from the current node. In our case, there are two direct child nodes with object IDs 66 and Object 66 is presented below:. Object 66 contains other child elements with ID 57, 69, 75, 97, and If we count all the elements, we can see that there are exactly 10 elements, which means 10 pages out of 10 pages.
Object 57 contains is declared as follows:. The contents of that PDF page can be found in an object We can see that the actual content of the PDF page is encoded with the FlateDecode, which is just a simple zlib encoding algorithm. With the knowledge we obtained, we can start generating incorrect PDF documents and feeding them to the various PDF readers. This implies the possibility of a vulnerability, which would need to be studied further.
At the end, if the vulnerability proves to be present, we can even write a PDF document that contains malicious code that is executed when the victim opens the PDF document with the vulnerable PDF reader on their target machine. In such cases, the whole machine might be compromised, since arbitrary malicious code can be executed just by opening a malicious PDF document. A new tab for your requested boot camp pricing will open in 5 seconds. If it doesn't open, click here. He is very interested in finding new bugs in real world software products with source code analysis, fuzzing and reverse engineering.
He also has a great passion for developing his own simple scripts for security related problems and learning about new hacking techniques. He knows a great deal about programming languages, as he can write in couple of dozen of them.
His passion is also Antivirus bypassing techniques, malware research and operating systems, mainly Linux, Windows and BSD. Thanks The link to the sample PDF is broken for me? Does this sample PDF have an entry for the metadata stream section of the documents catalog?
Your email address will not be published. Figure 1: Adobe Acrobat Reader DC vulnerabilities This is an important indicator that we should regularly update our PDF Reader, because the number of vulnerabilities discovered recently is quite daunting.
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In this Series. Copy-paste compromises Hacking Microsoft teams vulnerabilities: A step-by-step guide 10 most popular password cracking tools [updated ] Popular tools for brute-force attacks [updated for ] Top 7 cybersecurity books for ethical hackers in How quickly can hackers find exposed data online?
Related Bootcamps. Incident Response. Nima says:. November 7, at am. Danilo Zama says:. January 6, at pm. July 11, at am. Carlos Estevam says:. August 18, at pm. Majid says:. November 14, at pm. Zeus says:. I shall see him, but not now: I shall behold him, but not nigh: there shall come a Star out of Jacob, and a Sceptre shall rise out of Israel, and shall smite the corners of Moab, and destroy all the children of Sheth.
Numbers Bible Rank: 3, You and Aaron are to count according to their divisions all the men in Israel who are twenty years old or more and able to serve in the army. From twenty years old and upward, all in Israel who are able to go forth to war you and Aaron shall number, company by company.
From twenty years old and upward, all that are able to go forth to war in Israel: thou and Aaron shall number them by their armies. Of Simeon; Shelumiel the son of Zurishaddai. And Israel abode in Shittim, and the people began to commit whoredom with the daughters of Moab.
And Miriam and Aaron spake against Moses because of the Ethiopian woman whom he had married: for he had married an Ethiopian woman. The key advances in Numbers are summarised below: Version. Adds features to allow charts in Keynote and Pages to be automatically updated when changed in Numbers files.
Support added for OS X Lion features such as "full screen", "resume", "auto save" and "versioning". Includes improved compatibility with Excel documents, the ability to hide and unhide rows and columns amd filters.
Launched with a new UI to match that found in Pages and Keynote, and also includes the ability to create interactive charts. Apple iWork Numbers 2. MacWorld review of Numbers 3. PDF is a file format developed by Adobe Systems for representing documents in a manner that is separate from the original operating system, application or hardware from where it was originally created.
It all points to Jesus Christ. The prophecies point to Him. The miracles He performed remind us that He is God. His teachings were amazing, and His control of nature was real. The entire Bible is about Him. It is about our God. The Open Bible. New American Standard Bible. Thomas Nelson Publishers, Menahem Mansoor.
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