Malicious PDF — malware analysis report

Static analysis result for SHA-256 831c1dcce9107570…

MALICIOUS

PDF

79.8 KB Created: 2021-09-19 07:31:14 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-11-21
MD5: 1974f86fdf526fb298559e5288dfc90a SHA-1: ef82e52d3d07cdbdf9e5c9469e82e5b893b85865 SHA-256: 831c1dcce9107570b0e0ce5fda151bb862cc013da374ef7d6e45babb79244a46
126 Risk Score

Malware Insights

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

The sample was detected as a malicious PDF by ML classifiers and ClamAV, indicating a high likelihood of malicious intent. Heuristics identified it as a link farm on disposable hosting, with numerous embedded URLs pointing to other PDF files. This suggests a campaign focused on SEO manipulation or distributing further malicious content through a network of linked PDFs.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9968

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
  • 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://tomasmrazek.cz/userfiles/file/sagelixogulunegoguke.pdf In PDF document text
    • http://studioesflores.pl/obrazy/file/74929360603.pdfIn PDF document text
    • http://healthywithhart.com/res/file/sifevepoxokasesexago.pdfIn PDF document text
    • http://floramarble.com/uploads/wisavinebexesibudigepoj.pdfIn PDF document text
    • http://erodiertechnik-wenzel.de/userfiles/file/lifijazetitewadoponiworo.pdfIn PDF document text
    • http://www.lbf-cosmetics.com/website/wp-content/plugins/formcraft/file-upload/server/content/files/1613468fb1bb8f---28642422671.pdfIn PDF document text
    • https://carrieres-pierre.com/userfiles/file/53909639164.pdfIn PDF document text
    • https://kujainspectors.com/candyticket/uploads/page_images/files/mupiwejowawoxuk.pdfIn PDF document text
    • https://dolnoslaskialarmsmogowy.pl/imgturysta/files/wilijobujoludezeriraluz.pdfIn PDF document text
    • https://postelezmasivu-praha.cz/ckfinder/userfiles/files/vebowijilumetekaxubilitu.pdfIn PDF document text
    • http://dtyxbpzx.com/filespath/files/20210902091940.pdfIn PDF document text
    • http://xn----7sbabaajmdfbk3ddf3azka3b6a2r.xn--p1ai/ckfinder/userfiles/files/29923322358.pdfIn PDF document text
    • https://infravoip.com/wp-content/plugins/super-forms/uploads/php/files/1138893060e86c5a5e37f57528db35d5/fakakuwirikudaw.pdfIn PDF document text
    • https://stonebuild.bg/f/uploads/files/3441948990.pdfIn PDF document text
    • http://tidomusica.com/uploads/files/202109171437542180.pdfIn PDF document text
    • http://skisun.it/userfiles/files/bulexafivijovetufisej.pdfIn PDF document text
    • https://gplacestracker.com/userfiles/file/lixibofefugu.pdfIn PDF document text
    • https://milsagliksen.org/upload/ckfinder/files/80878621468.pdfIn PDF document text
    • http://becro-plast.hr/wp-content/plugins/formcraft/file-upload/server/content/files/161460b16a4b5f---48073128363.pdfIn PDF document text
    • http://abwingsbuffalo.com/uploads/files/ramewadusogogonupe.pdfIn PDF document text
    • http://pogotowienaukowe.com/Upload/file/gumadakase.pdfIn PDF document text
    • http://nepalbestcargo.com/userfiles/file/ratirojoxojupo.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/fzgW7-mxBc0/uplcv?utm_term=super+smash+flash+2+steamPDF 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_off0000d253.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD253 10600 bytes
SHA-256: 698851021028b2be595023089744a29d7426b494d92da9d13ad87428567d21bd
font_01_sfnt_off0000eaa1.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xEAA1 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off000102b3.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x102B3 18100 bytes
SHA-256: 008c15ac871cb5ba11444362e5fa18c3d8220685545bad15e50ed36f5025e2d1