Malicious PDF — malware analysis report

Static analysis result for SHA-256 5f0f757ae95269b5…

MALICIOUS

PDF

71.2 KB Created: 2021-02-17 04:13:55 +02:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-10-16
MD5: 7336ae5af241d4658eb57bd3f6b3942a SHA-1: 24e7e982e42bc2d9393552a34452a5acf2a2750b SHA-256: 5f0f757ae95269b58b46fce7a51b6f58acec47fafd9821e34bdcd60b6894a6fa
126 Risk Score

Malware Insights

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

The sample was detected as malicious by ML classifiers and ClamAV, indicating a high likelihood of malicious intent. It contains numerous embedded URLs, with at least one pointing to a suspicious domain ('jacksth.ru') and another acting as a link farm on disposable hosting. The document body, though heavily obfuscated, contains metadata suggesting it was generated by wkhtmltopdf, a tool sometimes used to create malicious PDFs. The presence of external URIs and the link farm heuristic strongly suggest the PDF's purpose is to redirect users to malicious websites.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9997

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://jacksth.ru/strik?utm_term=is+empathy+healthy PDF link annotation
    • http://zeraseb.66ghz.com/maziwulejuganek.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4389823/normal_5fce62bf33593.pdfIn PDF document text
    • https://nijumaweka.weebly.com/uploads/1/3/1/3/131379182/9247556.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4371812/normal_60291e10ce43e.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4374379/normal_600101f70d109.pdfIn PDF document text
    • http://subonus.ru/43082846268sdcji.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn PDF document text
    • http://tazomibege.epizy.com/impact_of_globalization_on_culture_essay.pdfIn PDF document text
    • https://s3.amazonaws.com/bidemewufa/construction_company_organization_chart_template.pdfIn PDF document text
    • http://kavimefejemud.rf.gd/bazonogoramiwim.pdfIn PDF document text
    • https://s3.amazonaws.com/nefagolom/age_of_empires_1_ios.pdfIn PDF document text
    • http://wasalesex.epizy.com/exploring_science_hsw_edition_year_9_answers.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_off0000defd.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xDEFD 5000 bytes
SHA-256: e15fa9764b294ea117e5955bd8bdf791cf2039e1d056f79a44369e8bd28473db
font_01_sfnt_off0000efdd.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xEFDD 9480 bytes
SHA-256: 30529cfcfa234016b36e217c859a6156f2e9b8071a2e1bb552fa2c3b616dc737

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