Malicious PDF — malware analysis report

Static analysis result for SHA-256 a4c5d8dee2d4b93e…

MALICIOUS

PDF

72.1 KB Created: 2021-06-09 16:50:29 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-11-25
MD5: d5b2b2dc4a9280644288700f010ab180 SHA-1: cd311994e94edec483ec11e90e5c8fdcd5e99695 SHA-256: a4c5d8dee2d4b93ec3d2980ac23da2fb66878281f38d7328b64b40d4df32835c
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, many pointing to disposable domains and potentially for SEO manipulation. The ML classifier strongly indicated maliciousness, and the PDF_SEO_LINK_FARM heuristic confirms the presence of a link farm. While no scripts were extracted, the sheer volume of outbound links suggests a malicious intent, possibly to distribute malware or lead users to phishing sites.

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://philabc.ru/pbw?utm_term=griffiths+electromagnetic+theory PDF link annotation
    • https://static.s123-cdn-static.com/uploads/4475204/normal_5fe498d09ae46.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4407747/normal_605c9d6275b78.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4407729/normal_5fd1128c0d5ec.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4450259/normal_60053888e1122.pdfIn PDF document text
    • https://nanuvofekoredam.weebly.com/uploads/1/3/5/3/135385966/veseputonavisa.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4408583/normal_6006e59fc69f5.pdfIn PDF document text
    • https://lekakuvikel.weebly.com/uploads/1/3/1/3/131380005/3317613.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4420039/normal_5ff84852c9d4d.pdfIn PDF document text
    • https://badipixurer.weebly.com/uploads/1/3/4/4/134456466/debag_palalep_nuwiriti.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4481403/normal_60bd42626d438.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4481994/normal_60318225e06ae.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4452400/normal_60403b2557928.pdfIn PDF document text
    • https://fizabogozof.weebly.com/uploads/1/3/2/8/132815807/3978702.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4388825/normal_60be9299135dd.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4453334/normal_6069980494e01.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4416675/normal_601de96788a3b.pdfIn PDF document text
    • https://xinejusitap.weebly.com/uploads/1/3/4/6/134630468/powovixenope.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn PDF document text
    • http://natofuke.pbworks.com/w/file/fetch/144585870/ap_polytechnic_lecturer_exam_paper.pdfIn PDF document text
    • http://tagexoba.pbworks.com/w/file/fetch/144422319/3899302553.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_off0000dbf0.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xDBF0 5428 bytes
SHA-256: d6f736862483ea8f2e8882548e2080eb31cd80d765511e9376bea71f0820ad9d
font_01_sfnt_off0000ee4b.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xEE4B 11016 bytes
SHA-256: 041c4b763c5707d4b39f24de150dca8276955289f0773f413bbd103642b67b47

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