Malicious PDF — malware analysis report

Static analysis result for SHA-256 a81a722270486ca1…

MALICIOUS

PDF

39.3 KB Created: 2020-04-28 21:38:35 +03:00 Authoring application: wkhtmltopdf 0.12.1.4 (via Qt 4.8.6)
MD5: 2fabea3535d8ff234f39a853f5cc4741 SHA-1: 391596327e7cf02be9aa88dd287accc130ba7c06 SHA-256: a81a722270486ca18c21cdd0fa4307f7dbda81c19cdfdbc1dbe22176bebe12cc
94 Risk Score

Malware Insights

MITRE ATT&CK
T1566.002 Spearphishing Attachment T1204.002 Malicious Link

The PDF document's primary function appears to be a lure, using the title 'Maltese falcon book free' to attract users. It contains a significant number of embedded external links, identified by the PDF_SEO_LINK_FARM heuristic, pointing to various PDF files on different domains. This suggests a link farm or SEO manipulation tactic rather than direct payload delivery. The ML classifier strongly indicated maliciousness.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9981

Heuristics 4

  • Small PDF contains mass external PDF link farm critical PDF_SEO_LINK_FARM
    Small PDF contains many clickable external PDF links, mostly clustered on one host. This matches generated SEO/link-farm PDF carriers used to route users into malicious or unwanted-software delivery chains, rather than a normal document citation pattern.
  • External URI info PDF_URI
    PDF contains an external URL action
  • Object number defined twice with different bodies info PDF_DUPLICATE_OBJ_BODY_INCREMENTAL
    The same indirect object (N G) is defined more than once with different body bytes. First-wins and last-wins readers will resolve different content, which is a parser-confusion shape used by targeted PDFs. Body-only differences are common in benign incremental updates, so severity is raised only when the duplicate carries active content.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://davidmillsengineering.com/uploads/1/3/0/6/130639990/130639990.html#maltese+falcon+book+free
    • http://elysian.support/uploads/1/3/1/3/131382439/xubavewetixunavu.pdf
    • http://sorcerynails.com/uploads/1/3/1/4/131438499/1994334.pdf
    • http://clickclackfitness.com/uploads/1/3/0/6/130640029/sidaravug-fewigozu.pdf
    • http://tizzybits.com/uploads/1/3/0/3/130313836/momijitus-nininubazig-xalevifoxakole.pdf
    • http://fairystonetradingpost.com/uploads/1/3/0/7/130776874/zoxajabasefar.pdf
    • http://clickclackfitness.c
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/pdf/1.3/
    • http://ns.adobe.com/xap/1.0/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/xap/1.0/rights/

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off000073a1.bin
6b6d1c2a6b75463b18bb9e8fe7f05ebaa8f16bd292ab28fbcb42e9a1421c4b06		 pdf-font-stream PDF embedded font (sfnt) at offset 0x73A1 7820 bytes

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