Malicious PDF — malware analysis report

Static analysis result for SHA-256 def0bf6937c28938…

MALICIOUS

PDF

95.8 KB Created: 2021-04-09 20:24:57 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-05-26
MD5: 33b4d3120e5bf2d30e6834880ce4327b SHA-1: 1e7b932e782ab1f685a6d90a1a3eea369d3d71af SHA-256: def0bf6937c289382a3a010101d90044ead392747a02643376b74a750c8dec33
126 Risk Score

Malware Insights

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

The PDF document was flagged by ML classifiers and ClamAV as malicious, specifically as a phishing trojan. It contains a high number of embedded URLs, many pointing to seemingly benign domains but structured as link farms, suggesting an attempt to obscure malicious destinations. The document body is heavily obfuscated and contains metadata indicating it was generated by wkhtmltopdf, a tool often used to create PDF versions of web pages, further supporting the phishing lure hypothesis.

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/sovurusogizafubeb.pdf In PDF document text
    • https://ambrose.edu/sites/default/files/webform/kubuxodadiwozubak.pdfIn PDF document text
    • http://www.pbttphtk.gov.my/sites/default/files/webform/xaduxiwipel.pdfIn PDF document text
    • http://pilgrimland.com/sites/default/files/webform/resume-uploads/40494538869.pdfIn PDF document text
    • http://www.friendlycc.com/sites/default/files/webform/tojatovovezugunubi.pdfIn PDF document text
    • https://www.woonsocketri.org/system/temporary/webform/bogobovimefegaf.pdfIn PDF document text
    • https://www.jwico.com/sites/default/files/webform/vuvosiritixulufanili.pdfIn PDF document text
    • http://spotlight-sites.com/sites/default/files/webform/sizewavajifur.pdfIn PDF document text
    • https://www.enwidth.com/sites/default/files/webform/resumes/fudigebifofonixetizitalu.pdfIn PDF document text
    • https://www.a1touchsolution.nl/sites/default/files/26511902049.pdfIn PDF document text
    • https://www.termis.org/system/files/webform/776381217.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/1eyvgo/aqOO/~3/3vuEKuznOb8/uplcv?utm_term=beauty+and+the+billionaire+based+on+accidental+babiesPDF link annotation
    • https://community.princeton.edu/system/files/webform/26098210740.pdfIn PDF document text
    • https://thesanfordschool.asu.edu/sites/default/files/webform/moxogugudufagelo.pdfIn PDF document text
    • https://printandmail.princeton.edu/system/files/webform/50156150340.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_off0001391b.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x1391B 5316 bytes
SHA-256: 99631347ae6b2a0b7750f98e763ed2bdaa8cf5dfb274a616e8202a6f48f6f094
font_01_sfnt_off00014b2b.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x14B2B 11280 bytes
SHA-256: 952c0ea9d59c77e2a8fb5ab4311f488c1a745081114ac3bc72549b6afa0a648d

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