Malicious PDF — malware analysis report

Static analysis result for SHA-256 f98fbb651136bc85…

MALICIOUS

PDF

63.7 KB Created: 2021-04-16 21:55:48 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-05-26
MD5: 744637a7895126ccce9002392b2b364a SHA-1: c25c70f81907f319f6b392e910d2060672573c16 SHA-256: f98fbb651136bc85adc16b9cc8a84d9745625719717d8dc9e9203889bc599429
126 Risk Score

Malware Insights

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

The PDF file was flagged by a machine learning classifier and ClamAV as malicious, specifically as a phishing trojan. It contains numerous embedded URLs, many pointing to seemingly legitimate domains but used in a link farm pattern, suggesting an attempt to manipulate search engines or redirect users to malicious sites. The document body is heavily obfuscated and contains metadata indicating it was generated by wkhtmltopdf, a tool often used to create PDFs from web content, further supporting the link farm hypothesis.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9997

Heuristics 5

  • ClamAV: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0
  • 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://www.ofalloncasting.com/sites/default/files/webform/tirudekamevajoluzagobumi.pdf In PDF document text
    • http://www.guninetwork.org/system/files/webform/heirri_proposals/zarogoluvesiriwameb.pdfIn PDF document text
    • https://www.visitsavannah.com/sites/default/files/webform/59391310887.pdfIn PDF document text
    • http://cicatsalud.com/html/sites/default/files/webform/99284441703.pdfIn PDF document text
    • http://www.pbttphtk.gov.my/sites/default/files/webform/95941620813.pdfIn PDF document text
    • http://pilgrimland.com/sites/default/files/webform/resume-uploads/40494538869.pdfIn PDF document text
    • http://cicatsalud.com/html/sites/default/files/webform/32675510575.pdfIn PDF document text
    • https://www.telluridescience.org/sites/default/files/tstc-applications/30232074114.pdfIn PDF document text
    • http://www.guninetwork.org/system/files/webform/heirri_proposals/rarapenebeku.pdfIn PDF document text
    • https://web.liderpapel.com/sites/default/files/webform/kivalin.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/BvfzZFkJO3s/uplcv?utm_term=palabras+de+enlace+para+hacer+una+introduccionPDF link annotation
    • https://lib.asu.edu/system/files/webform/85824103047.pdfIn PDF document text
    • https://www.vub.be/sites/vub/files/webform/43319512550.pdfIn PDF document text
    • https://printandmail.princeton.edu/system/files/webform/98467125123.pdfIn PDF document text
    • https://ec.europa.eu/eip/agriculture/sites/default/files/webform/juvuwudonuvusenovirem.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_off0000bd4d.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xBD4D 5300 bytes
SHA-256: 6f3f67e58e85b0af3c7fec1f1b556bcf8b4cf3e756352a336b772fa8968776e9
font_01_sfnt_off0000cf3d.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xCF3D 10500 bytes
SHA-256: 3780cda912fa38778d28ce0dc4d1001496fd56d15129fe1e9d2939cad03e0aba

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