Malicious PDF — malware analysis report

Static analysis result for SHA-256 c81c8bf57b077087…

MALICIOUS

PDF

76.2 KB Created: 2021-07-18 04:30:05 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-11
MD5: c689060bed45cf8a42b91f5c0d5ad269 SHA-1: a4d2c32fbc31b996dad3ba13a3a8cf66c0945360 SHA-256: c81c8bf57b077087af9b3078dc31ef51aa806f2cff32499141eb0dbea265bd70
156 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The file is identified as malicious by ClamAV and an ML classifier, with multiple heuristics indicating it functions as a link farm pointing to compromised CMS uploads. The embedded URLs, though some are marked benign, are part of a larger pattern of directing users to potentially malicious sites. The PDF structure itself is exploited to host these links, suggesting an attempt to distribute further malicious content or conduct phishing.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9948

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://stroynerud-sm.ru/wp-content/plugins/formcraft/file-upload/server/content/files/1608283c041210---mojan.pdf In PDF document text
    • https://messianic.live/wp-content/plugins/super-forms/uploads/php/files/e501827fc0456c806f0757f9d09f52b9/gufafewuvowuzifuvotuk.pdfIn PDF document text
    • http://0-50.ru/userfiles/file/wavudi.pdfIn PDF document text
    • http://adanateknikservis.web.tr/wp-content/plugins/formcraft/file-upload/server/content/files/160bdef65dd90e---58100711897.pdfIn PDF document text
    • https://1sis.com/wp-content/plugins/formcraft/file-upload/server/content/files/160b9b88446b9d---50137581249.pdfIn PDF document text
    • http://technoculture.cz/admin/upload/file/suxabelulesib.pdfIn PDF document text
    • http://geredekombiservisi.com/userfiles/file/36864897578.pdfIn PDF document text
    • https://okinawa4d.com/contents//files/pekemojolugabowamo.pdfIn PDF document text
    • https://www.plsok.com/wp-content/plugins/super-forms/uploads/php/files/b014b0b439309f6597443bb3f2d44b92/73171716536.pdfIn PDF document text
    • http://stigstudiotecnico.it/userfiles/files/74817113236.pdfIn PDF document text
    • https://enville.com/wp-content/plugins/formcraft/file-upload/server/content/files/16084c077c1957---jewuzibizorur.pdfIn PDF document text
    • https://fiberglasssupplydepot.com/userfiles/file/dowuxuxosi.pdfIn PDF document text
    • http://gewoongroen.eu/app/webroot/files/userfiles/files/7105477242.pdfIn PDF document text
    • http://smartmedicaleg.com/wp-content/plugins/formcraft/file-upload/server/content/files/16086cb842c958---nasaj.pdfIn PDF document text
    • http://fotocaroli.it/userfiles/files/86773190383.pdfIn PDF document text
    • https://nhatngudongkinh.com/upload/ckupload/files/kivunazolunuluvuz.pdfIn PDF document text
    • http://www.onekaddy.com/wp-content/plugins/formcraft/file-upload/server/content/files/160b1eda8b0d7e---zepokadirujenojolomeruna.pdfIn PDF document text
    • https://revapackers.com/wp-content/plugins/super-forms/uploads/php/files/94n95crase0edua224e8oovb72/80282843518.pdfIn PDF document text
    • http://veronicanealhome.com/wp-content/plugins/formcraft/file-upload/server/content/files/2/1609f431a34a1b---gonowesuwovin.pdfIn PDF document text
    • http://studiopignotti.it/userfiles/files/84307017723.pdfIn PDF document text
    • http://marcth.pl/media/fck/file/61690019160.pdfIn PDF document text
    • https://www.lindopoint.it/wp-content/plugins/super-forms/uploads/php/files/a35832c3a1ae52286b60c6846ab3e06e/meguvamuxuxuduvuturumi.pdfIn PDF document text
    • https://ahi.com.ua/wp-content/plugins/super-forms/uploads/php/files/7e17cbf948f5fa0d0cd84ef5b6616e3b/laluwowukovibo.pdfIn PDF document text
    • https://calldidocta.com/wp-content/plugins/super-forms/uploads/php/files/f3e80bfb78b3089ff4c582ad16a9ef6f/92430986803.pdfIn PDF document text
    • https://feedproxy.google.com/~r/1eyvgo/aqOO/~3/BvfzZFkJO3s/uplcv?utm_term=possessive+adjectives+and+object+pronouns+exercises+pdfPDF 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_off0000bdcd.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xBDCD 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_01_sfnt_off0000d5df.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD5DF 19400 bytes
SHA-256: 6b71eba1cfc604abaa1c50bc21102d6f44a049a8519ef53b0d1b517f3acc62a4
font_02_sfnt_off00010775.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x10775 11108 bytes
SHA-256: 5408ee60cf95e52b24836a787917c173966a6e010267d99c078e385c4f9d9871

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