Malicious PDF — malware analysis report

Static analysis result for SHA-256 b281a708dfd0c43c…

MALICIOUS

PDF

67.6 KB Created: 2021-04-15 22:43:35 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-05-29
MD5: f1a3a2d609e9abe85f1410c549fb4189 SHA-1: 58d92c55197a97f6b7bc83bcd8554f4e3650c800 SHA-256: b281a708dfd0c43c3696bffba22e0ca06d53b2b4532170e1c2404c1f29810a4e
126 Risk Score

Malware Insights

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

The PDF file was detected as malicious by ML classifiers and ClamAV, indicating a high likelihood of malicious intent. The document contains numerous embedded URLs, many pointing to seemingly benign academic or organizational sites, but the overall structure suggests a link farm designed to obscure malicious destinations. The presence of 'utm_term' parameters in some URLs and the 'PDF_SEO_DISPOSABLE_LINK_FARM' heuristic suggest an attempt to manipulate search engine results or disguise the true purpose of the links. While no scripts were explicitly extracted, the PDF format itself can embed JavaScript, which could be used to execute malicious actions or redirect users.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

Heuristics 5

  • ClamAV: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0
  • 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://ambrose.edu/sites/default/files/webform/71027525942.pdf In PDF document text
    • https://architecturaldesigninc.com/sites/default/files/vudezuluxi.pdfIn PDF document text
    • https://www.mainephilanthropy.org/sites/default/files/guvobirewuge.pdfIn PDF document text
    • https://www.termis.org/system/files/webform/53478461308.pdfIn PDF document text
    • http://www.pbttphtk.gov.my/sites/default/files/webform/kafavepovimurajubek.pdfIn PDF document text
    • http://www.pacificsportfraservalley.com/sites/default/files/webform/zasadavatemomafupe.pdfIn PDF document text
    • https://www.jts.org.jo/sites/default/files/webform/1653940235.pdfIn PDF document text
    • https://www.enwidth.com/sites/default/files/webform/resumes/ziwisotug.pdfIn PDF document text
    • http://pilgrimland.com/sites/default/files/webform/resume-uploads/64296936159.pdfIn PDF document text
    • http://cicatsalud.com/html/sites/default/files/webform/dizage.pdfIn PDF document text
    • http://cicatsalud.com/html/sites/default/files/webform/61943826361.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/3vuEKuznOb8/uplcv?utm_term=ford+8n+tractor+owners+manual+downloadPDF link annotation
    • https://community.princeton.edu/system/files/webform/setokan.pdfIn PDF document text
    • https://minorsoncampus.princeton.edu/system/files/webform/libovonudipiguriteg.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_off0000ca54.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xCA54 5324 bytes
SHA-256: 76b4c65d3f4e0f98344e658f54a4dd4c67df31eb58efe3044ac1c599831caa0a
font_01_sfnt_off0000dc6d.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xDC6D 11072 bytes
SHA-256: c4b7d41f669415f1931a20098dbaf7b2754858de07e7a7a6cacd5c854c2a2c14

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