Malicious PDF — malware analysis report

Static analysis result for SHA-256 3a8985a9e56b0373…

MALICIOUS

PDF

66.0 KB Created: 2021-02-18 11:08:19 +02:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-05-23
MD5: 4bb80e5c1d876ba2085ae992de007c99 SHA-1: 723075f7a2be07a4a7a9b96c795d1f148b4b5d75 SHA-256: 3a8985a9e56b0373e5c47a75d39ac21e8abea4ca10b51b4f9ec6e56a4aafc65c
126 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1203 Exploitation for Client Execution

The PDF file contains a large number of external links pointing to other PDF documents hosted on various domains, many of which appear to be disposable. This behavior is indicative of a link farm, likely used for SEO manipulation or to distribute further malicious content. The ML classifier strongly flagged this PDF as malicious, supporting the assessment of its suspicious nature.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

Heuristics 5

  • 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.
  • Small PDF is a non-clustered link farm on disposable hosting medium PDF_SEO_DISPOSABLE_LINK_FARM
    Small PDF contains many clickable external PDF links spread thin across many distinct hosts (no single dominant host), corroborated by a utm_term SEO-redirector link and/or links parked on free/disposable content hosts. This is the 'free document/template' SEO phishing PDF family, which ranks for search queries and routes users into payload/redirect chains, rather than a normal document citation pattern. The PDF itself carries no exploit — the risk is the linked destinations.
  • 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 https://jacksth.ru/wix?keyword=cari%25C3%25B1osa+en+ingles PDF link annotation
    • https://static.s123-cdn-static.com/uploads/4489245/normal_5ff5654b925a7.pdfIn PDF document text
    • https://lemirupuzomive.weebly.com/uploads/1/3/2/8/132814022/3792296.pdfIn PDF document text
    • http://mrt-64.ru/does_exocytosis_use_active_or_passive_transporti6q6g.pdfIn PDF document text
    • https://cdn.sqhk.co/xubipoxeguza/hium4gh/dososep.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4408330/normal_5fe2c5a7f1d81.pdfIn PDF document text
    • https://cdn.sqhk.co/vakusukereju/hfjcdhg/tifivixexojo.pdfIn PDF document text
    • https://cdn.sqhk.co/puvubuzu/ehjijid/xoroxewijekavuxabepal.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4408485/normal_6001ca9dd906f.pdfIn PDF document text
    • https://venonaneguwar.weebly.com/uploads/1/3/5/3/135398509/rogumixolusedu.pdfIn PDF document text
    • https://bituxusod.weebly.com/uploads/1/3/4/3/134347303/xuparewoveg.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4481662/normal_60183ac8399ef.pdfIn PDF document text
    • https://cdn.sqhk.co/lifudidu/53xciaT/one_clue_crossword_answers_chapter_4.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4480182/normal_602258e780250.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4501027/normal_601b1e7da5026.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4416490/normal_602be72ba31e6.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4425506/normal_5ffcd54c00d2a.pdfIn PDF document text
    • https://kusafulidofet.weebly.com/uploads/1/3/4/0/134017607/d3aa0189e.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn PDF document text
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#In PDF document text
    • http://purl.org/dc/elements/1.1/In PDF document text
    • http://ns.adobe.com/pdf/1.3/In PDF document text
    • http://ns.adobe.com/xap/1.0/In PDF document text
    • http://ns.adobe.com/xap/1.0/mm/In PDF document text
    • http://ns.adobe.com/xap/1.0/rights/In PDF document text
    • http://scripts.sil.org/OFLIn PDF document text

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000c646.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xC646 4968 bytes
SHA-256: 15b5ccaca30e368a787ec44e5670c5777ba38585928fdec24c1c892f5e744620
font_01_sfnt_off0000d6f2.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD6F2 10816 bytes
SHA-256: a5e10b0a5d34d8ae4b7ece81403a01266f92fe0eea2d2af5e7f46b413217fa9f

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