Malicious PDF — malware analysis report

Static analysis result for SHA-256 81fdf257f4f6fbff…

MALICIOUS

PDF

81.0 KB Created: 2021-10-18 01:54:12 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-11-23
MD5: 871fe21b191e6cf3f72be4926f96f0db SHA-1: 686f50db65947acee32f34b2663126c4ca285ba1 SHA-256: 81fdf257f4f6fbff0c0ae2288136895dcec57c374f9cafdc21613998e317c659
156 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The PDF contains numerous embedded URLs, many of which point to compromised CMS upload storage or are part of a link farm on disposable hosting, indicating a phishing or malware distribution attempt. The ClamAV detection and ML classifier strongly suggest malicious intent. While no scripts were explicitly extracted, the nature of the embedded URLs and the heuristic firings point towards a malicious document, likely delivered via spearphishing.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9968

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://recviem.ru/img/upload/75718434037.pdf In PDF document text
    • https://www.abrasco.org.br/ckfinder/userfiles/files/45263360678.pdfIn PDF document text
    • http://ginkgokatsudb.com/uploads/files/25660279072.pdfIn PDF document text
    • https://sharidendesignasphalt.com/wp-content/plugins/super-forms/uploads/php/files/846ff4cd751893ebb37a3012e14ad44b/21940115783.pdfIn PDF document text
    • http://trubaopt.ru/content/file/mabibij.pdfIn PDF document text
    • http://abw10thstreetne.com/uploads/files/16640343073.pdfIn PDF document text
    • http://laptopplus.be/app/webroot/files/userfiles/files/29438172493.pdfIn PDF document text
    • http://www.solarwindependence.com/ckfinder/userfiles/files/renuzedakufenuzikuku.pdfIn PDF document text
    • http://lerucherdesanges.fr/userfiles/file/jeganadubifugew.pdfIn PDF document text
    • http://bilcafe.it/userfiles/file/56893903923.pdfIn PDF document text
    • http://kraemer-duennebacke.de/files/file/nonimazerinugi.pdfIn PDF document text
    • https://gaseg.com/wp-content/plugins/super-forms/uploads/php/files/hqek0u2k378rk9i5iar8ijd0ij/riwif.pdfIn PDF document text
    • https://testgit.begurholidays.com/uploads/userfiles/files/66948886320.pdfIn PDF document text
    • http://www.farparts.cl/wp-content/plugins/formcraft/file-upload/server/content/files/16169408fc31f7---31409271546.pdfIn PDF document text
    • https://www.helpfulhunks.com.au/wp-content/plugins/formcraft/file-upload/server/content/files/1616c8f72121be---zosijemibewigutuziburu.pdfIn PDF document text
    • http://www.gainerwindows.ca/wp-content/plugins/super-forms/uploads/php/files/c5c11jcpjvetlveg33qmugoua7/wipugidikatutak.pdfIn PDF document text
    • https://ctapigroup3.com/contents/files/dobejofuzi.pdfIn PDF document text
    • http://sbstroy53.ru/img/files/42408308892.pdfIn PDF document text
    • http://cnzgks.com/userfiles/file///runanegapeguxonu.pdfIn PDF document text
    • http://ekvatorbl.com/userfiles/file/18592266107.pdfIn PDF document text
    • http://hosungtour.net/FileData/ckfinder/files/20211017_302CBFABF6CAF222.pdfIn PDF document text
    • http://another-partner.morefriendship.com/upload/files/kigux.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Gsjc/~3/7xhmvLXWVJc/uplcv?utm_term=microwave+flowers+to+dryPDF 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_off0000d7c3.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD7C3 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_01_sfnt_off0000efd5.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xEFD5 18712 bytes
SHA-256: f913d4deef19f27c70b5d0e95b77753eb27f2a44017bbdd9ca3de80ec526d944
font_02_sfnt_off00011e8e.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x11E8E 10624 bytes
SHA-256: 29feff08e40ed1055456a4a43b6a9ad2282f9741020eeb0d20bcc86a3cee3418