Malicious PDF — malware analysis report

Static analysis result for SHA-256 a77b5832379c214f…

MALICIOUS

PDF

68.2 KB Created: 2021-04-19 20:55:04 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-05-26
MD5: ce6103caa98bfdec99c567ba42c2270f SHA-1: c4b7361b0d34889683ce54b48e7c77cfe41d915f SHA-256: a77b5832379c214f34843390d1e2c6b13f2260c52f2ab16a0e91bad70a694cb1
126 Risk Score

Malware Insights

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

The PDF document was flagged by ML classifiers and ClamAV as malicious, indicating a phishing or malware distribution attempt. It contains numerous embedded URLs, many pointing to disposable domains, suggesting a link farm designed to redirect users to malicious content. The document body, though heavily obfuscated, appears to be a lure related to 'Saxon calculus solutions manual'. No scripts were extracted, but the PDF structure and URL patterns are indicative of a phishing campaign.

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://ambrose.edu/sites/default/files/webform/93854264345.pdf In PDF document text
    • https://web.liderpapel.com/sites/default/files/webform/21411595718.pdfIn PDF document text
    • http://www.muttypawsacademy.com/sites/default/files/webform/vaccines/powevalixerofewum.pdfIn PDF document text
    • http://cicatsalud.com/html/sites/default/files/webform/93477879009.pdfIn PDF document text
    • https://ambrose.edu/sites/default/files/webform/52499587618.pdfIn PDF document text
    • https://www.osgeurope.com/sites/osg-corporate.dev/files/webform/27880179426.pdfIn PDF document text
    • https://www.enwidth.com/sites/default/files/webform/resumes/90018929780.pdfIn PDF document text
    • http://russian-ice-spb.ru/sites/default/files/webform/files/42282539280.pdfIn PDF document text
    • https://www.woonsocketri.org/system/temporary/webform/danajon.pdfIn PDF document text
    • https://ambrose.edu/sites/default/files/webform/9979090083.pdfIn PDF document text
    • http://www.grotekeukens.be/sites/default/files/webform/gmawards2018/87706268510.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/BkSY9tpko7c/uplcv?utm_term=saxon+calculus+solutions+manualPDF link annotation
    • https://minorsoncampus.princeton.edu/system/files/webform/zotatati.pdfIn PDF document text
    • https://www.ice.cam.ac.uk/sites/www.ice.cam.ac.uk/files/webform/8342566550.pdfIn PDF document text
    • https://campusrec.princeton.edu/system/files/webform/16616798570.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_off0000cf3a.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xCF3A 5020 bytes
SHA-256: a58dc2ca841a26bdfd86877993f9012f86ed2a7d7e7330ba56c7dbef812a3232
font_01_sfnt_off0000e041.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE041 10516 bytes
SHA-256: cb0208b522eba073dab3a07292bbd8fbbc733d29e540a9930452684367bfdfb8

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