Malicious PDF — malware analysis report

Static analysis result for SHA-256 37a8825a82ea42be…

MALICIOUS

PDF

77.9 KB Created: 2021-04-07 15:24:35 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-05-26
MD5: 9ff7fa91cc75541b515ebe5ff16e0acc SHA-1: c830854fed304d14769430ae45ec8eb5602b850f SHA-256: 37a8825a82ea42be757fa72b7fbd4ef953505084ed5bedd885dcb58874355f88
126 Risk Score

Malware Insights

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

The sample is a PDF file flagged by ML classifiers and ClamAV as malicious. It contains numerous embedded URLs, with one heuristic specifically identifying it as a link farm on disposable hosting. The document body, though heavily obfuscated, contains metadata suggesting it was generated by wkhtmltopdf, a tool often used to create PDFs from web content. The presence of multiple PDF_URI heuristics indicates attempts to redirect the user to external resources.

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 http://www.pacificsportfraservalley.com/sites/default/files/webform/banofamuwidobekoke.pdf In PDF document text
    • https://www.a1touchsolution.nl/sites/default/files/wozupidojenebimovom.pdfIn PDF document text
    • https://www.natsihwa.org.au/sites/default/files/webform/72917344941.pdfIn PDF document text
    • https://grossenbacher.co.nz/en/system/files/avoidance-training-certificates/basolidigululaba.pdfIn PDF document text
    • https://www.a1touchsolution.nl/sites/default/files/43963154407.pdfIn PDF document text
    • https://www.woonsocketri.org/system/temporary/webform/bogobovimefegaf.pdfIn PDF document text
    • https://www.mothercare.ro/sites/default/files/webform/resumes/topijetidilotifoga.pdfIn PDF document text
    • https://www.osgeurope.com/sites/osg-corporate.dev/files/webform/bedadijone.pdfIn PDF document text
    • http://www.grotekeukens.be/sites/default/files/webform/gmawards2018/dakatiwilu.pdfIn PDF document text
    • http://www.grotekeukens.be/sites/default/files/webform/gmawards2018/98751459569.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn PDF document text
    • http://feedproxy.google.com/~r/Uplcv/~3/PmAiG5ZyT-k/uplcv?utm_term=bridget+jones+the+edge+of+reason+pdfPDF link annotation
    • https://drones.princeton.edu/system/files/webform/janewif.pdfIn PDF document text
    • https://www.vub.be/sites/vub/files/webform/ludazerubadariwevulefaxu.pdfIn PDF document text
    • https://printandmail.princeton.edu/system/files/webform/mizol.pdfIn PDF document text
    • https://minorsoncampus.princeton.edu/system/files/webform/tuvoluxasivawujunaz.pdfIn PDF document text
    • https://ec.europa.eu/eip/agriculture/sites/default/files/webform/sukazejaso.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_off0000f0fb.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF0FB 5396 bytes
SHA-256: 6777a64debf7008b885d1c9d8162fa3fa966469b31ec586f26adf602f22b32e7
font_01_sfnt_off0001035c.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x1035C 11624 bytes
SHA-256: 6de510ff5be127af99146a5bb421a09b13ae442fbb59e5f57b6dcd97367a8a08

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