Malicious PDF — malware analysis report

Static analysis result for SHA-256 98a91db2b5d14d79…

MALICIOUS

PDF

74.9 KB Created: 2021-02-22 09:05:26 +02:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-10-27
MD5: 380feaf12ac83d8457c8dc37633cbc68 SHA-1: d374f984f62ed4a328aa333489241c3c8bcf6782 SHA-256: 98a91db2b5d14d797699c8e6c6085cc8e3a3ef5cc938ef2d5338a12110236a32
66 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1059.007 JavaScript

The PDF contains numerous embedded URLs, many of which point to disposable hosting and are part of a link farm, indicating a malicious intent to redirect users. The ML classifier strongly flagged this PDF as malicious. Although no scripts were explicitly extracted, the presence of embedded URLs and the heuristic 'PDF_SEO_DISPOSABLE_LINK_FARM' suggest the document is designed to lead users to potentially harmful sites, likely for phishing or malware delivery.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

Heuristics 4

  • 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://baarspo.ru/strik?utm_term=digital+signal+processing+course+syllabus PDF link annotation
    • http://excschool.ru/480946986032xggk.pdfIn PDF document text
    • https://cdn.sqhk.co/jagakutojut/heSKuxt/kukawulag.pdfIn PDF document text
    • http://yewes.fun/470976368870v4s2.pdfIn PDF document text
    • http://gradstroy.su/25449698611ctar2.pdfIn PDF document text
    • https://cdn.sqhk.co/jitolado/jgEBH6v/plague_inc_fungus_brutal_walkthrough_no_genes.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4391611/normal_5fda47c599e15.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4366959/normal_5fe7bc677087a.pdfIn PDF document text
    • http://itsamorem.com/besimalafiwufixawozikurigm2n2.pdfIn PDF document text
    • https://cdn.sqhk.co/ragejeli/G5jdidB/battle_simulator_for_clash_royale_apk.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4367279/normal_5fec1d31cc9ee.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4474446/normal_6005db0a1d6f4.pdfIn PDF document text
    • https://cdn.sqhk.co/navotezive/jiichjs/66381917329.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn PDF document text
    • https://s3.amazonaws.com/rejiner/multiple_choice_answer_sheet_online.pdfIn PDF document text
    • https://s3.amazonaws.com/latufenaw/togomufojeto.pdfIn PDF document text
    • https://s3.amazonaws.com/nafibanefexex/2483247576.pdfIn PDF document text
    • https://s3.amazonaws.com/penale/blend_s_meme_template.pdfIn 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_off0000e6b2.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE6B2 5340 bytes
SHA-256: eeaa7e83b1a018056f638fc7325e559b896140a936549cc2c47dcd4748237c72
font_01_sfnt_off0000f8fe.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF8FE 11024 bytes
SHA-256: 451e77367b192e0eb2f86833a7a01eb50a035142259c577cdce6a2c34d2e345d

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