Malicious PDF — malware analysis report

Static analysis result for SHA-256 f33a3b361a0771b5…

MALICIOUS

PDF

88.9 KB Created: 2021-10-09 20:58:53 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-11-25
MD5: 84182cf1286b67d62b19ef55e2fb10a3 SHA-1: 47049f80c568e54ec2f0ebc6502824c32d7b3c7a SHA-256: f33a3b361a0771b50d1ef7312252e8556aba918fd64dd03103bfbcc5cca4bd9c
66 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious Link

The sample is a PDF file flagged by a machine learning classifier as malicious. It contains numerous embedded URLs, many of which point to PDF files on various domains, suggesting a link farm or content distribution network. One heuristic specifically identifies it as a 'PDF_SEO_DISPOSABLE_LINK_FARM', indicating a likely attempt to manipulate search engine results or distribute further malicious content. No scripts were extracted, and the document body was unreadable, limiting the ability to determine a more specific attack pattern.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9988

Heuristics 4

  • 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://anthonygillant.com/userfiles/file/99208309393.pdf In PDF document text
    • http://gsprojekt.eu/userfiles/files/22003041069.pdfIn PDF document text
    • http://rallyteamwalraven.nl/file/46646139283.pdfIn PDF document text
    • http://congluc.com/upload/files/29821324387.pdfIn PDF document text
    • http://rimini-portal.de/bilderarchiv/file/watiwej.pdfIn PDF document text
    • https://sibirprokat.ru/ckfinder/userfiles/files/sanekakepeketeke.pdfIn PDF document text
    • https://callmarkinvestments.fortunekenya.com/callmark/files/bifogi.pdfIn PDF document text
    • http://adabaskimerkezi.com/upload/file/zuzag.pdfIn PDF document text
    • https://riwg.in/userfiles/file/28642419522.pdfIn PDF document text
    • http://a2itsolutions.com/chop/multimedia/userfiles/file/84958793210.pdfIn PDF document text
    • http://ducnhua.com/upload/files/54482654746.pdfIn PDF document text
    • https://pmsp-me.com/userfiles/files/27533885225.pdfIn PDF document text
    • http://uniquehotelsolutions.com/files/others/5246003826.pdfIn PDF document text
    • https://matfplayer.com/calisma2/files/uploads/liluwejekiwisimugule.pdfIn PDF document text
    • http://9262895.ru/ckfinder/userfiles/files/bifenosubivaz.pdfIn PDF document text
    • http://uyaviation.com/wp-content/plugins/formcraft/file-upload/server/content/files/1615c2cfbd6319---58038883240.pdfIn PDF document text
    • http://www.kinoimaging.nl/wp-content/plugins/formcraft/file-upload/server/content/files/1615cc178bc32c---tefur.pdfIn PDF document text
    • https://asztromiskolc.hu/ckfinder/userfiles/files/77668421102.pdfIn PDF document text
    • https://gsm.company/ckfinder/userfiles/files/budibigev.pdfIn PDF document text
    • https://kamhosting.nl/ckfinder/userfiles/files/gejaximolejojufipam.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/6naE_Nh8_CY/uplcv?utm_term=chicken+and+cheese+rissolesPDF link annotation
    • 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_off0000f13a.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF13A 10492 bytes
SHA-256: 8913927b37d776e2a9a913f524d7ca3e2c6dfa7747f680c3bc84157b1bcad882
font_01_sfnt_off000108ff.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x108FF 20324 bytes
SHA-256: 5028adb22d77432a26efe4963debd54d164acc0bdbad0611e7ce6d79ba63debc
font_02_sfnt_off00013e31.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x13E31 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1

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