Malicious PDF — malware analysis report

Static analysis result for SHA-256 520641d88bb81e7f…

MALICIOUS

PDF

80.7 KB Created: 2021-06-23 01:10:15 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-11-24
MD5: 3e04e34c304577100bf3bcc81181537d SHA-1: 0c28fd3dfe653587020eb5f6494d893e17c616c3 SHA-256: 520641d88bb81e7f15733ed55fec87fe7449bf74baadee5d8bf006f0f4757eaf
156 Risk Score

Malware Insights

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

This PDF file was detected as malicious by ClamAV and an ML classifier, indicating a high likelihood of malicious intent. It contains numerous links to external websites, many hosted on compromised CMS platforms or disposable domains, suggesting a link farm used for phishing or malware distribution. The document body, though heavily obfuscated, contains metadata suggesting it is an 'answer key', a common lure for malicious documents.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9996

Heuristics 6

  • ClamAV: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0
  • PDF link farm points to compromised-WordPress upload storage medium PDF_COMPROMISED_CMS_UPLOAD_LINK_FARM
    PDF contains multiple clickable links, across many distinct hosts, whose targets are random-slug files parked in the upload directories of vulnerable WordPress form plugins (FormCraft, Super Forms). This is the hallmark of the 'free document/template' SEO phishing PDF family, which ranks for search queries and routes users into payload/redirect chains hosted on compromised sites. The PDF itself carries no exploit — the risk is the linked destinations.
  • 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://kbchina.de/upload/89022128370.pdf In PDF document text
    • https://a2designbg.com/userfiles/file/99232972022.pdfIn PDF document text
    • http://www.photobreak.com.br/wp-content/plugins/formcraft/file-upload/server/content/files/16073d509aa1fa---lubivapijotufojafakubo.pdfIn PDF document text
    • http://emrc.ie/upload/imagecontent/file/tubawapafarameputa.pdfIn PDF document text
    • https://www.azulejositurry.com/wp-content/plugins/super-forms/uploads/php/files/822ctv1nak4lnm8rddumb2s6k1/1144979378.pdfIn PDF document text
    • https://ahi.com.ua/wp-content/plugins/super-forms/uploads/php/files/05f7e4bcadd00cef4be63d3ec20d89d8/25374845290.pdfIn PDF document text
    • http://www.realisthotel.com/wp-content/plugins/formcraft/file-upload/server/content/files/160861d4d45b2e---98054820200.pdfIn PDF document text
    • https://earthchartercities.org/wp-content/plugins/formcraft/file-upload/server/content/files/16080fa1fe59af---jebaxuxosejaralom.pdfIn PDF document text
    • https://flardochform.se/userfiles/file/46795075075.pdfIn PDF document text
    • https://www.traveltimevipp.com/wp-content/plugins/super-forms/uploads/php/files/bcff8a2fc7372d3629f7b6a66d51ef69/84688424937.pdfIn PDF document text
    • https://frasertechno.com/wp-content/plugins/formcraft/file-upload/server/content/files/1607426d7637f7---fenivikopebolijujabuw.pdfIn PDF document text
    • http://barrarioservicos.com.br/wp-content/plugins/formcraft/file-upload/server/content/files/1607f2ca1deff8---53454863006.pdfIn PDF document text
    • https://bbpartner.cz/userfiles/file/54662012705.pdfIn PDF document text
    • http://coyada.com/up_images/up_images/sigedofudegapevukezexibeb.pdfIn PDF document text
    • http://a-swiss.com/upload/userfiles/file/zakitifusezosifono.pdfIn PDF document text
    • http://global-poseg.com/wp-content/plugins/formcraft/file-upload/server/content/files/1607e052c378bc---vokanozoxuw.pdfIn PDF document text
    • https://dipinkrishna.com/wp-content/plugins/formcraft/file-upload/server/content/files/1609458ffa63c6---29044517319.pdfIn PDF document text
    • http://tumwebthailand.com/ckfinder/userfiles/files/25745558317.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://fedorahosted.org/lohitIn PDF document text
    • https://feedproxy.google.com/~r/1eyvgo/aqOO/~3/YTWXjIUwRh0/uplcv?utm_term=ailet+2019+answer+keyPDF 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://scripts.sil.org/OFLIn PDF document text

Extracted artifacts 4

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000e063.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE063 5088 bytes
SHA-256: ac3b9dd93d031d411a2981f0803aefefc7725e83bc86df165eee67a5916da10e
font_01_sfnt_off0000f1bd.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF1BD 11428 bytes
SHA-256: 90d5bc2951ef7e7bf1d8f4d82d30d4e42a5661b003ed99e953ebdfcba3f8f129
font_02_sfnt_off00011868.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x11868 4324 bytes
SHA-256: 1158d95dac44631f497756703988ba3645251422e7ff0015d3fca430225e7c3e
font_03_sfnt_off00012668.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x12668 3836 bytes
SHA-256: b6807f7435dc9e82a8f7b7544431dc57cf03563da55dfdaf0bc3e2e4b1fef7e8

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