Malicious PDF — malware analysis report

Static analysis result for SHA-256 fcae40e5918191d0…

MALICIOUS

PDF

72.9 KB Created: 2021-04-20 05:54:39 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-05-26
MD5: d1dad8fe0774dbc782afa51678ddc74f SHA-1: 196f5e47664bc4fb1b3ba2869b74e1fcfe9ef5d6 SHA-256: fcae40e5918191d07380fa4e197fc30860c8b0e1e15f2f081d560f9c008238f1
126 Risk Score

Malware Insights

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

The sample was flagged by ML classifiers and ClamAV as malicious, specifically as a phishing trojan. Heuristics indicate it functions as a link farm, directing users to multiple external URLs, some of which are hosted on potentially disposable domains. The document body is heavily obfuscated and contains metadata suggesting it was generated by wkhtmltopdf, a tool often used to create PDFs from web content, further supporting the link farm/phishing hypothesis.

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://www.newburghgroup.com/sites/default/files/webform/resumes/41319995155.pdf In PDF document text
    • https://ambrose.edu/sites/default/files/webform/46846662681.pdfIn PDF document text
    • https://www.mainephilanthropy.org/sites/default/files/guvobirewuge.pdfIn PDF document text
    • https://ambrose.edu/sites/default/files/webform/7968200385.pdfIn PDF document text
    • http://portal-mysigma.com/system/files/student-proof/tevesifisota.pdfIn PDF document text
    • http://pilgrimland.com/sites/default/files/webform/resume-uploads/tixatikuwasa.pdfIn PDF document text
    • http://www.guninetwork.org/system/files/webform/heirri_proposals/rarapenebeku.pdfIn PDF document text
    • https://vectorcorp.net/sites/default/files/webform/resume/dufovomajaxavekasodulep.pdfIn PDF document text
    • https://www.blplegal.com/sites/default/files/webform/25596831819.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/1eyvgo/aqOO/~3/S30rS-6n6vg/uplcv?utm_term=what+is+the+most+confusing+wordPDF link annotation
    • https://campusrec.princeton.edu/system/files/webform/93394875634.pdfIn PDF document text
    • https://www.vub.be/sites/vub/files/webform/piwolumubixu.pdfIn PDF document text
    • https://gradfutures.princeton.edu/system/files/webform/xafuzekimizitigemuseli.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_off0000e175.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE175 5508 bytes
SHA-256: d1cdb1ed78c045530513563be1442d679af116ebaa66f4f19c1549d78424f428
font_01_sfnt_off0000f41b.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF41B 10340 bytes
SHA-256: 4517835294cf4af1a550a5cc498b2313effb4be2d07885bbfa63819ee01e985a

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