Malicious PDF — malware analysis report

Static analysis result for SHA-256 ecb81551e565a71d…

MALICIOUS

PDF

72.8 KB Created: 2021-09-05 11:09:08 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-16
MD5: 4143c7ce0059dd14d064c9c05ee42832 SHA-1: 46afa319438e3b8b7eee2ab2bda5ccde3fdfbc12 SHA-256: ecb81551e565a71d577b885580bbafaf2f38da0c765cfdf53f32396295877f2e
156 Risk Score

Malware Insights

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

The PDF file was flagged by ML classifiers and ClamAV as malicious, specifically as a phishing trojan. Heuristics indicate it functions as a link farm, with numerous embedded URLs pointing to compromised WordPress upload directories and other potentially malicious sites. The document body is heavily obfuscated and appears to be generated by wkhtmltopdf, suggesting it's not intended for direct user reading but rather to host links.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9982

Heuristics 6

  • ClamAV: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0
  • 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://www.1000ena.com/wp-content/plugins/formcraft/file-upload/server/content/files/160bc6eb1a5f5f---zusibawisolofumami.pdf In PDF document text
    • https://xn--78-6kce7dfhb9dwb.xn--p1ai/wp-content/plugins/super-forms/uploads/php/files/0df22732a2ce0332800207ff9c7a56bf/xunisawazilejo.pdfIn PDF document text
    • http://hotelgiottotorino.com/userfiles/files/81874635030.pdfIn PDF document text
    • http://www.nandomoraes.com.br/wp-content/plugins/formcraft/file-upload/server/content/files/16086bcb310acc---warijojanemufanod.pdfIn PDF document text
    • https://anyimaker.com/upload/users/files/17671855799.pdfIn PDF document text
    • https://schreinerheusi.de/wp-content/plugins/formcraft/file-upload/server/content/files/16081d4ca3b1e8---22425318218.pdfIn PDF document text
    • http://artin-intranet.com/ckupload/files/zufad.pdfIn PDF document text
    • http://pericosrentcar.com.mx/wp-content/plugins/formcraft/file-upload/server/content/files/16086b3945bf7d---75561689763.pdfIn PDF document text
    • https://gs-hemeringen.de/ablage/userfiles/files/2707815150.pdfIn PDF document text
    • http://chinajnbt.com/images/upload/File/jetukojeruzudinogunip.pdfIn PDF document text
    • http://artecgroupservices.com/imagenes/file/98199700300.pdfIn PDF document text
    • http://xn--80akij1ajew.xn--p1ai/wp-content/plugins/formcraft/file-upload/server/content/files/160b788e7f2906---gazowaralegara.pdfIn PDF document text
    • http://www.molinoag.com/wp-content/plugins/formcraft/file-upload/server/content/files/1609151d6db802---86980199093.pdfIn PDF document text
    • https://afra24.com/basefile/afra24/files/7963165734.pdfIn PDF document text
    • https://envida-nieuws.nl/bsb_website/upload_fck/file/faluvoti.pdfIn PDF document text
    • https://uzmanwebci.com/calisma2/files/uploads/gaperifim.pdfIn PDF document text
    • https://vernadoc.com/wp-content/plugins/super-forms/uploads/php/files/cfb871701926556bfdcadc9a514b4435/ginusuzubodenimovu.pdfIn PDF document text
    • http://gesundezellen.de/neu/userfiles/file/jimudegejuwakanefolewiw.pdfIn PDF document text
    • http://phs60sand70sdecadesreunion.com/clients/880504/File/jupakufowupebiso.pdfIn PDF document text
    • http://kaufdeinauto.de/wp-content/plugins/formcraft/file-upload/server/content/files/1608ab5aecf1b9---dinoluguvipenetalexujiz.pdfIn PDF document text
    • http://ytbozhuo.com/upload/file/04012403412.pdfIn PDF document text
    • http://minerva-collection.net/files/files/piwobozukevedolarog.pdfIn PDF document text
    • http://vdavloeren.be/userfiles/files/39177129028.pdfIn PDF document text
    • http://wypelnienia.kratex.pl/wp-content/plugins/super-forms/uploads/php/files/b7be84cb6794ece504ea4f0cebc8c066/20233221955.pdfIn PDF document text
    • https://feedproxy.google.com/~r/skout/mBVl/~3/YTWXjIUwRh0/uplcv?utm_term=albinismo+oculo-cutan%C3%A9+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_off0000ba36.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xBA36 16324 bytes
SHA-256: ca686d82df96650b43b7b1571d2a9edc22928746ddf32a7c35f124ada2fff455
font_01_sfnt_off0000e45e.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE45E 10956 bytes
SHA-256: 206ae5cc903978760be9502e768b9719315b9d1a0d3d7795f070956503c607f7
font_02_sfnt_off0000fda0.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xFDA0 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1