Malicious PDF — malware analysis report

Static analysis result for SHA-256 b87d95ae88ae11a2…

MALICIOUS

PDF

72.8 KB Created: 2021-04-08 14:25:02 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-05-26
MD5: e4ecaf78e69adf56e59f8e9139ca79f5 SHA-1: 5efd27f176d842d3ce2d22d431bcee0343d6bbb8 SHA-256: b87d95ae88ae11a244dea97b0052dcdf603785277bc27abf3f4ce94fecf55324
126 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious Link

The PDF file was flagged by a machine learning classifier and ClamAV as malicious, specifically as a phishing trojan. Heuristics indicate it functions as a link farm on disposable hosting, with numerous embedded URLs pointing to various domains. The document body, though heavily obfuscated, contains metadata suggesting it was generated by wkhtmltopdf, a tool often used to create malicious PDFs.

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 http://klm3fg.grhosting.cz/sites/default/files/webform/files/kokibilelage.pdf In PDF document text
    • https://www.osgeurope.com/sites/osg-corporate.dev/files/webform/povufukawonafano.pdfIn PDF document text
    • http://www.pbttphtk.gov.my/sites/default/files/webform/3018222411.pdfIn PDF document text
    • https://www.afscme65.org/system/files/webform/tikat.pdfIn PDF document text
    • https://www.osgeurope.com/sites/osg-corporate.dev/files/webform/47147916176.pdfIn PDF document text
    • https://www.enwidth.com/sites/default/files/webform/resumes/21555212736.pdfIn PDF document text
    • https://www.enwidth.com/sites/default/files/webform/resumes/paxifufal.pdfIn PDF document text
    • https://www.jwico.com/sites/default/files/webform/23528315583.pdfIn PDF document text
    • https://www.uts.cw/sites/default/files/webform/tidenopuzi.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn PDF document text
    • http://feedproxy.google.com/~r/Uplcv/~3/Om9ozkHLxGw/uplcv?utm_term=catholic+liturgical+year+pdfPDF link annotation
    • https://ec.europa.eu/eip/agriculture/sites/default/files/webform/vojevo.pdfIn PDF document text
    • https://minorsoncampus.princeton.edu/system/files/webform/janoruzafasolefixos.pdfIn PDF document text
    • https://community.princeton.edu/system/files/webform/36479690150.pdfIn PDF document text
    • https://thesanfordschool.asu.edu/sites/default/files/webform/fapivo.pdfIn PDF document text
    • https://lib.asu.edu/system/files/webform/bidemuf.pdfIn PDF document text
    • https://www.healthdata.org/sites/default/files/resumes/58023923203.pdfIn PDF document text
    • https://printandmail.princeton.edu/system/files/webform/fasulegok.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_off0000df15.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xDF15 5244 bytes
SHA-256: c70ce24ec240150112f3a7f2d326820c890dce63b5303e65be67bb80abd9ca8c
font_01_sfnt_off0000f0ed.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF0ED 11064 bytes
SHA-256: 2b6403fe64b4d24467f9f9debf86b3bc4efd2b983b25c329f21801b27a0794c9

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