Malicious PDF — malware analysis report

Static analysis result for SHA-256 91f5b2ac4647bacc…

MALICIOUS

PDF

76.2 KB Created: 2021-07-21 10:31:45 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-08-20
MD5: be8cf5cddd1961cdb57a94ef72f2ef11 SHA-1: ecf4c91c57a5a8f95bf72d50ca909c17c548d992 SHA-256: 91f5b2ac4647bacc1d0e04da13f360c0f8461bef0c203abfe817a09d248099a9
136 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The PDF file contains heuristics indicating it is a phishing lure, specifically using an image to link to an SEO redirector for a 'free-download phishing' attempt. The primary IOC is the redirector URL, which is likely used to host or lead to the actual malicious payload. The ML classifier and ClamAV detection further support the malicious nature of this PDF.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9001

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
  • Image lure linking to an SEO redirector (free-download phishing) high PDF_SEO_UTM_REDIRECTOR_LINK
    PDF embeds an image with little or no body text and a clickable link to a multi-word utm_term / FeedBurner-proxied SEO redirector — the 'free ebook / solution-manual / document download' phishing family that ranks for natural-language search queries and routes the user into a payload/redirect chain. The PDF carries no exploit; the risk is the linked destination. Flagged structurally (image lure + SEO redirector) so it does not depend on a ClamAV/ML signature, and regardless of how many filler text pages the lure carries.
  • 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://irlanc.ru/square?utm_term=becker+world+of+the+cell+8th+edition+pdf PDF link annotation
    • https://static1.squarespace.com/static/60bf69b23f3791685666e32d/t/60f0a38d08c731162adaaa8e/1626383246138/7177490896.pdfIn PDF document text
    • https://static1.squarespace.com/static/60bf6bff0d8d387fecc8b153/t/60f4859981f38b2058938ec9/1626637721897/movoteze.pdfIn PDF document text
    • https://static1.squarespace.com/static/60aac4dd19f082755c4e5c69/t/60f5b1d59fcba71c4acdb24a/1626714581696/3842653234.pdfIn PDF document text
    • https://static1.squarespace.com/static/60bf6c89a2b0b938881bcf91/t/60e8f65e37da2614570c3884/1625880159098/wodumuteni.pdfIn PDF document text
    • https://static1.squarespace.com/static/60bf6c89a2b0b938881bcf91/t/60f4d63627519501fc235926/1626658358620/baxiwem.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://dejavu.sourceforge.netIn PDF document text
    • http://dejavu.sourceforge.net/wiki/index.php/LicenseIn PDF document text

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000c932.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xC932 16464 bytes
SHA-256: 126df3e52d89d0c61fec3c9dc474a239407088feca4fb32b83d6613dea5580dd
font_01_sfnt_off0000f3d6.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF3D6 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off00010bed.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x10BED 10828 bytes
SHA-256: ce9bc73eab50fc43b9b251604811cd6adec70ec3e747757d9e51a32d7bd80a21

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