Malicious PDF — malware analysis report

Static analysis result for SHA-256 81dcd57dad02b133…

MALICIOUS

PDF

65.6 KB Created: 2021-04-10 02:36:58 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-05-26
MD5: b6b242a2d6f582e50d594ab64503472c SHA-1: 7d89c8bb171765cc63ae54a1f4472778cd09ae26 SHA-256: 81dcd57dad02b133c4888671470fd3def2ea621115a6c762739c76ddc1b261fd
126 Risk Score

Malware Insights

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

The PDF file was flagged by ML classifiers and ClamAV as malicious, indicating a high likelihood of malicious intent. The presence of numerous embedded URLs, many pointing to potentially disposable domains or link farms, suggests a phishing or malware distribution scheme. While no scripts were explicitly extracted, the PDF structure and heuristic firings point towards an attempt to exploit users by disguising malicious content within a seemingly legitimate document.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

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.termis.org/system/files/webform/88699151804.pdf In PDF document text
    • https://www.jwico.com/sites/default/files/webform/66271497470.pdfIn PDF document text
    • https://www.uts.cw/sites/default/files/webform/dupoxemijuwavamuvugorudiz.pdfIn PDF document text
    • http://www.sumnercountyhospital.org/sites/default/files/webform/sixativitav.pdfIn PDF document text
    • https://www.natsihwa.org.au/sites/default/files/webform/72789215659.pdfIn PDF document text
    • https://www.uts.cw/sites/default/files/webform/xewaz.pdfIn PDF document text
    • https://ambrose.edu/sites/default/files/webform/20598750849.pdfIn PDF document text
    • https://www.jwico.com/sites/default/files/webform/minokoniniwige.pdfIn PDF document text
    • http://www.friendlycc.com/sites/default/files/webform/kilolegejesap.pdfIn PDF document text
    • http://cicatsalud.com/html/sites/default/files/webform/buvonajevomowetizebijix.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/~3/3vuEKuznOb8/uplcv?utm_term=ashrae+handbook+2019+pdfPDF link annotation
    • https://www.vub.be/sites/vub/files/webform/siwujomizawafoxewop.pdfIn PDF document text
    • https://ec.europa.eu/eip/agriculture/sites/default/files/webform/vojevo.pdfIn PDF document text
    • https://minorsoncampus.princeton.edu/system/files/webform/27732669772.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_off0000c24e.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xC24E 5772 bytes
SHA-256: f4527410fff0bbab08a0d61366748a15e58dbcf92c9c0455916a10841a54b8d1
font_01_sfnt_off0000d5e0.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD5E0 10544 bytes
SHA-256: a052d67fe70c3e2cd306b1b9ab4a74b408a7d916517f69276710c102697d3a5d

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