Malicious PDF — malware analysis report

Static analysis result for SHA-256 b8c91b2e65250a65…

MALICIOUS

PDF

81.8 KB Created: 2021-01-18 14:13:03 +02:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-10-27
MD5: 98388a9960c39f3af5c2631c46afa204 SHA-1: 762a7af3da482e6b1c93e031bba416e5ac4d107a SHA-256: b8c91b2e65250a65345b85bf0d2cc610187fb6066ce94672227ccb5656f53c31
186 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1203 Exploitation for Client Execution

The PDF contains a large number of external links, many hosted on disposable domains, indicating a link farm or SEO manipulation tactic. The ClamAV detection and ML classifier strongly suggest malicious intent, likely related to phishing or malware distribution via these links. The document body is heavily obfuscated and contains metadata suggesting it was generated by wkhtmltopdf, a tool often used to create PDF versions of web pages.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

Heuristics 6

  • 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 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://trafffi.ru/123?utm_term=extenze+reviews+2019 PDF link annotation
    • https://wikefazopikevi.weebly.com/uploads/1/3/4/7/134715570/wibugegezapufef.pdfIn PDF document text
    • https://subuletow.weebly.com/uploads/1/3/4/2/134265429/8242780.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4365591/normal_5fff649d0ac5c.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4490516/normal_5fb9912630cf1.pdfIn PDF document text
    • https://luwujejajevobo.weebly.com/uploads/1/3/1/4/131407494/e1ff0cdb9f2.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4446494/normal_5fc597df90729.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4368242/normal_5fdac751b38f6.pdfIn PDF document text
    • https://jodiwovuf.weebly.com/uploads/1/3/4/3/134368652/42ec53023a9b6c6.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4428054/normal_5fe9d5c9932f6.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4366360/normal_5f8753f7b8c29.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4417644/normal_5f96faa393dc5.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4451551/normal_5ffc7f2797dd7.pdfIn PDF document text
    • https://mokazeke.weebly.com/uploads/1/3/1/3/131384082/2a834331cf366d.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn PDF document text
    • https://s3.amazonaws.com/mesotodimus/29813440678.pdfIn PDF document text
    • https://s3.amazonaws.com/safago/66833842226.pdfIn PDF document text
    • https://s3.amazonaws.com/tujeviwakirawu/risora.pdfIn PDF document text
    • https://s3.amazonaws.com/tugabijenovili/adjectives_used_as_nouns_worksheet.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_off00010642.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x10642 5148 bytes
SHA-256: 9078559ded09d3dfc383faea17206cab2a2c77f8a99b7ecfffcd5724d4bb16bf
font_01_sfnt_off000117fc.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x117FC 10052 bytes
SHA-256: 87c5824dc61204fc70c5b5e815118b44f91f21dd3396fc47fc48bcf86dcb0fd2

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