Malicious PDF — malware analysis report

Static analysis result for SHA-256 791cbafb4931a2bc…

MALICIOUS

PDF

75.8 KB Created: 2021-05-11 08:16:47 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-11-22
MD5: 41a2f8cdc9212aede0ecb29e15535838 SHA-1: 2cb64e2ffa474ccaff2b1114a5e2924f576e1f0f SHA-256: 791cbafb4931a2bc1e0caa1d41169826eeff823919c5035878e8ed858c5749ab
126 Risk Score

Malware Insights

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

The PDF file was identified as malicious by ML classifiers and ClamAV, indicating a high likelihood of malicious intent. It contains numerous embedded URLs, with one prominent URL suggesting a phishing or malware distribution lure related to 'English classes'. The heuristic 'PDF_SEO_DISPOSABLE_LINK_FARM' further supports the malicious nature by indicating the document is part of a link farm hosted on disposable domains.

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://druttle.ru/strik?utm_term=how+to+learn+english+classes+near+me PDF link annotation
    • https://cdn-cms.f-static.net/uploads/4411511/normal_5fe730683f46f.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4444369/normal_5feee157bb913.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4419415/normal_5fc84bd118e6c.pdfIn PDF document text
    • http://dfwshootersupply.com/motivational_speech_ideas_for_highschool_studentsemhvi.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4384628/normal_5fda671936a3b.pdfIn PDF document text
    • http://grantmedica.ru/buy_it_rent_it_profit4w7qq.pdfIn PDF document text
    • http://awpmode.com/50377097957rh05f.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4379837/normal_602c460093b48.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4483602/normal_60480a31ef944.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4387056/normal_5fdc49c8c0a92.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4457560/normal_5fcced7e3702b.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4414331/normal_6069e6286624c.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4472501/normal_6006b7171251b.pdfIn PDF document text
    • http://centerbluebadge.com/wrong_turn_2_tamil_dubbed_freehcjsc.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4493569/normal_604b973349d4f.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn PDF document text
    • http://lorabedujeweb.epizy.com/whatsapp_apkpure_latest_version.pdfIn PDF document text
    • https://uploads.strikinglycdn.com/files/9b2671cc-c46c-4ff1-8889-add44d2b1946/c_primer_stanley_lippman.pdfIn PDF document text
    • https://uploads.strikinglycdn.com/files/e143280d-eb6e-447b-9f06-1a84a10eb008/9496387042.pdfIn PDF document text
    • http://nifojasavolu.rf.gd/barron_s_sat_chemistry_13th_edition.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_off0000ea70.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xEA70 5264 bytes
SHA-256: daf957bb16344ad4b32fa90d803262dcf75aa16dd54cfde95f1559d837845875
font_01_sfnt_off0000fc3d.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xFC3D 11148 bytes
SHA-256: 051482d69d9e0fba65c11405c6a751562d8619066bf75ecb81e8884bf98aaf7d

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