Malicious PDF — malware analysis report

Static analysis result for SHA-256 cb8b931ce420d5ce…

MALICIOUS

PDF

83.4 KB Created: 2021-04-18 04:12:09 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-10-14
MD5: 8dc0e7189ddf2f2e14fedb0b4f82ec97 SHA-1: 114911dda40a7c1ec6f682fb582895d90f6c9001 SHA-256: cb8b931ce420d5ce3745303ac45f23e1450fc02e11783378af1872d40c9b2521
126 Risk Score

Malware Insights

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

The sample was detected by ClamAV as Pdf.Phishing.Trojan and flagged by an ML classifier, indicating malicious intent. The PDF contains numerous embedded URLs, many pointing to seemingly legitimate domains but likely serving as part of a link farm or redirection chain. The presence of PDF_SEO_DISPOSABLE_LINK_FARM heuristic suggests a tactic to obscure the final malicious destination. No scripts were extracted, but the overall structure and heuristic firings point towards a phishing or malware distribution campaign.

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.osgeurope.com/sites/osg-corporate.dev/files/webform/14219433733.pdf In PDF document text
    • https://ambrose.edu/sites/default/files/webform/sovurusogizafubeb.pdfIn PDF document text
    • http://cicatsalud.com/html/sites/default/files/webform/kizosilubim.pdfIn PDF document text
    • http://pilgrimland.com/sites/default/files/webform/resume-uploads/jitebetususi.pdfIn PDF document text
    • http://www.sumnercountyhospital.org/sites/default/files/webform/sinuwoxifazuroli.pdfIn PDF document text
    • https://vectorcorp.net/sites/default/files/webform/resume/dofivefodazewinewes.pdfIn PDF document text
    • http://www.muttypawsacademy.com/sites/default/files/webform/vaccines/taxevoxasubosiwugudabi.pdfIn PDF document text
    • https://www.woonsocketri.org/system/temporary/webform/kebadewanizokodijixupid.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/skout/mBVl/~3/cv9VXjIrmdE/uplcv?utm_term=mgma+salary+2020+redditPDF link annotation
    • https://www.ice.cam.ac.uk/sites/www.ice.cam.ac.uk/files/webform/17420147243.pdfIn PDF document text
    • https://lib.asu.edu/system/files/webform/61431168480.pdfIn PDF document text
    • https://community.princeton.edu/system/files/webform/64301273598.pdfIn PDF document text
    • https://community.princeton.edu/system/files/webform/putirufulexuxibo.pdfIn PDF document text
    • https://umatter.princeton.edu/system/files/webform/requests/72435273025.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_off0001065f.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x1065F 5528 bytes
SHA-256: cae958e09d5a9029702e8b35b2ebb1e4f82b6c71308617e9ffaaff46167ebf7e
font_01_sfnt_off0001191e.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x1191E 11808 bytes
SHA-256: 360d02bcf848cfb7337b86f62ebaa1706a2766c4349d6fbc883e2b86e6784511

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