Malicious PDF — malware analysis report

Static analysis result for SHA-256 f91c92b8e3ddf5e1…

MALICIOUS

PDF

37.9 KB Created: 2020-04-10 17:39:10 +03:00 Authoring application: wkhtmltopdf 0.12.1.4 (via Qt 4.8.6)
MD5: f3d3ac33dd06af7a2fb5c1a4055cf8bc SHA-1: f5d6b439a5f4afe56447c02d900cff4f976add24 SHA-256: f91c92b8e3ddf5e1304ebaa10159404d4384219d222cbbb607e0655fda7ec2c6
94 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The PDF file contains numerous external links pointing to a network of websites, many of which appear to be part of a link farm designed for SEO manipulation. The heuristic 'PDF_SEO_LINK_FARM' strongly indicates this malicious pattern. The document body, though partially corrupted, contains text related to 'Ejercicios de calistenia pdf' and mentions the wkhtmltopdf generator, suggesting a lure to disguise the malicious link distribution. The ML classifier also flagged this PDF with high confidence.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9999

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://azlanadnan.com/uploads/1/3/0/5/130588487/130588487.html#ejercicios+de+calistenia+pdf
    • http://centrohumanistico.us/uploads/1/3/0/6/130620470/b613b943.pdf
    • http://flavoredsprinkle.com/uploads/1/3/1/3/131379410/nitubij_xadizegutugubig_nogag_sexoso.pdf
    • http://pedahzur.org/uploads/1/3/0/7/130775084/renujunujopo.pdf
    • http://pmsellers.net/uploads/1/3/0/6/130621342/xofuk.pdf
    • http://asweetsart.com/uploads/1/3/0/6/130621525/kafivijelupepiz_lanoses_bajef_bewiw.pdf
    • http://ekklesiainsights.com/uploads/1/3/0/5/130539348/badiv_bapuvapuk_gaxibigano_dulatike.pdf
    • 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_off000069e7.bin
cc4a517b7bea978b092a79789361eeef4a54a6fc7bb5842e35d259e75c28c721		 pdf-font-stream PDF embedded font (sfnt) at offset 0x69E7 8652 bytes

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