In the last few days I have done some analysis on documents, especially . Then I thought, “Why not turn a analysis into an article?”

Let’s go to our case study:

I received a scan request for a PDF file that was reported to support an antivirus vendor, and it replied that the file was not malicious. Because the manufacturer’s analysis was not satisfactory, the team responsible for handling the incident requested a second opinion, since in other anti-virus tools the document was reported to be malicious. The team needed evidence to prove the risk involved in the file.

While conducting an initial analysis on the file, I identified that I had something suspicious:

- 0 e 1555545600 v beta t O nThHU UMz6qC6CCVgnquhNxCMEWJX8OI8IPkqKXVQ - Malicious PDF AnalysisSecurity Affairs

After an analysis in the structure of objects of the PDF it is possible to identify a malicious URL that is executed during the process of opening the document, that is to say, when the user opens the file in his station it executes of conceal form the call of the URL as shown below :

- 0 e 1555545600 v beta t pTY7abZMx4wgZnbhf eqJbPQNHsbLmXiUw8vHU262Mg - Malicious PDF AnalysisSecurity Affairs

When performing a domain verification it is possible to reach the IP bound to it:

- 0 e 1555545600 v beta t i Bnr7oJlfEWqsLxBUJ7RFyfD7E14ZtBOqgCyjsZouc - Malicious PDF AnalysisSecurity Affairs

When performing a URL reputation analysis, a malicious history is identified:

- 0 e 1555545600 v beta t sUqhpBmCJXruJdvfa04np dsTi2uTYBxI7ACjuFel6U - Malicious PDF AnalysisSecurity Affairs
- 0 e 1555545600 v beta t 6ol8rQTNnY kL99t0ATSZZWHLI1sdSND1UmfuZ0zXoE - Malicious PDF AnalysisSecurity Affairs

When performing an IP reputation analysis, a malicious history is identified:

- 0 e 1555545600 v beta t 4jb53oa3FQiUQc 5p2U2lsHoXdqJrLc IVUmZEc RfU - Malicious PDF AnalysisSecurity Affairs
- 0 e 1555545600 v beta t QZeTcWy t8q7iOy8JApYvlQtFEpGOclV V0F5qEDR9E - Malicious PDF AnalysisSecurity Affairs

The interesting thing is to think that years ago we would never say that infection would be possible through malicious code, URL, shellcode, through obfuscation inside documents like PDF, DOC, DOCx, XLS, XLSx and PPT. Most security tools must always be adapted to this new reality of and infection.

It is essential that security professionals are increasingly able to work with this type of analysis that the antivirus tool is not usually able to do, I leave here the hint about the importance of studying malicious document analysis.

About the author: Zoziel Freire

Cyber Security Analyst Content Writer of the portal: www.infosectrain.com Analyst document’s malicious CompTIA Security Analytics Professional LPIC-3 Enterprise Linux Professionals CompTIA Analyst Linkedin: https://www.linkedin.com/in/zozielfreire/

Twitter: https://twitter.com/zoziel

Pierluigi Paganini

(SecurityAffairs – PDF analysis, hacking)








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