Malicious PDF — malware analysis report

Static analysis result for SHA-256 a3536f261d212840…

MALICIOUS

PDF

76.5 KB Created: 2021-04-07 08:57:50 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-05-29
MD5: 88188001e8f2c56e4c129e854aef9482 SHA-1: ce040d1158221eeba11d747a283cd8a7268a38e5 SHA-256: a3536f261d212840607ad954bf42c9f8e1eacf35625c134b08fc1c9a1acdebd1
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, specifically as a phishing trojan. It contains numerous embedded URLs, many of which point to unknown or potentially malicious domains, suggesting a phishing or credential harvesting attempt. The document body, though heavily obfuscated, contains references to learning English grammar, likely a lure to entice users to click on the embedded links.

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 http://seiary.com/sites/default/files/webform/rec/jizexatunurometubukos.pdf In PDF document text
    • https://www.termis.org/system/files/webform/manejuwavujegajejumoxak.pdfIn PDF document text
    • https://www.a1touchsolution.nl/sites/default/files/95216779236.pdfIn PDF document text
    • https://ambrose.edu/sites/default/files/webform/58588935603.pdfIn PDF document text
    • https://www.afscme65.org/system/files/webform/11173368180.pdfIn PDF document text
    • http://seiary.com/sites/default/files/webform/rec/11252708720.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn PDF document text
    • http://www.daltonmaag.com/In PDF document text
    • http://feedproxy.google.com/~r/Uplcv/~3/BkSY9tpko7c/uplcv?utm_term=best+books+to+learn+english+grammar+pdfPDF link annotation
    • https://lib.asu.edu/system/files/webform/rutepirunumobapof.pdfIn PDF document text
    • https://community.princeton.edu/system/files/webform/xakefabobadu.pdfIn PDF document text
    • https://www.ice.cam.ac.uk/sites/www.ice.cam.ac.uk/files/webform/7842358922.pdfIn PDF document text
    • https://www.vub.be/sites/vub/files/webform/pagilavamuvawasaxega.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 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000decb.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xDECB 5496 bytes
SHA-256: 8b2aad7b03e8cc488d1ea27bda3b6fd8f209dbf886f4b522740f813b78988d88
font_01_sfnt_off0000f141.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF141 11176 bytes
SHA-256: 9a43ed25e4c129dc47e4e3b2c2c5205c9627b1002bcd7ab915de6b05dc71d2eb
font_02_sfnt_off0001172c.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x1172C 4324 bytes
SHA-256: a542ec26cea93e049a2e27cd59b1347dd9bbdea13775fd7b822b3c2b3136116f

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