Malicious PDF — malware analysis report

Static analysis result for SHA-256 21eace77c005558c…

MALICIOUS

PDF

86.0 KB Created: 2021-09-17 14:44:28 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-24
MD5: 9c31d2739bebf6b9c119ab02ac48247e SHA-1: 9e0a566eeeac3b5eb28b5146b02a3883c9996544 SHA-256: 21eace77c005558c2d3e3eb9fe84121f1c6c7b72e928f690bbd745ffeb9bcfae
156 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1203 Exploitation for Client Execution

The file was detected as malicious by ClamAV and an ML classifier, indicating a high likelihood of malicious intent. It functions as a link farm, with numerous embedded URLs pointing to PDF files hosted on various domains, some of which are identified as compromised CMS uploads. This suggests an attempt to manipulate search engine results or distribute further malicious content.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9947

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://huynhgiabaohotel.com/uploads/FCK/file/zegavobubijagezemuwi.pdf In PDF document text
    • http://krukaiart.com/userfiles/files/5760219122.pdfIn PDF document text
    • http://sipzip.com/userfiles/file/47167764665.pdfIn PDF document text
    • http://salonlomi.pl/wp-content/plugins/formcraft/file-upload/server/content/files/161427c299b1a6---nejuwufugatosuzovo.pdfIn PDF document text
    • https://propbrains.com/wp-content/plugins/super-forms/uploads/php/files/0cbc4467a7b9fefe4d07ed6e7b8477f6/52000708732.pdfIn PDF document text
    • http://nacyc.jp/Upload/file/11940864801.pdfIn PDF document text
    • https://bikeid.net/ckfinder/userfiles/files/32800110634.pdfIn PDF document text
    • http://dominoliberec.eu/images/file/files/boteda.pdfIn PDF document text
    • https://vespaclubcagliari.com/userfiles/file/3315413371.pdfIn PDF document text
    • http://balaton.varosom.hu/userfiles/files/bupezibepok.pdfIn PDF document text
    • http://kbcsisa.com/upload/fckeditor/file/kelekapojat.pdfIn PDF document text
    • https://www.hauptsache.cc/wp-content/plugins/formcraft/file-upload/server/content/files/16141bb0197d53---4581955161.pdfIn PDF document text
    • http://abwmercury.com/uploads/files/10265179363.pdfIn PDF document text
    • http://animalscipublisher.com/files/upfiles/file/gixajegivizibajuwesib.pdfIn PDF document text
    • https://wurstfargo.com/wp-content/plugins/super-forms/uploads/php/files/9e65092886a60b10bcb2cac859cddc92/26078361981.pdfIn PDF document text
    • http://specialcats.nl/media/files/71728823409.pdfIn PDF document text
    • https://trucraftsmanship.com/wp-content/plugins/formcraft/file-upload/server/content/files/1614322fcbd590---30148447789.pdfIn PDF document text
    • http://antitumor.org/filespath/files/20210913212837.pdfIn PDF document text
    • https://millersexpress.com/userfiles/file/44516016924.pdfIn PDF document text
    • https://dnm.tw/uploads/files/202109012024389078.pdfIn PDF document text
    • http://bajcsidavidfoto.com/_user/file/gofexorudujipofomigu.pdfIn PDF document text
    • http://zelene-centrum.cz/webpagebuilder/ckfinder/userfiles/files/toxasejegixexixofiretof.pdfIn PDF document text
    • https://djhelaly.com/wp-content/plugins/super-forms/uploads/php/files/da30b5813107dff98c072f5fb818f59f/83583461425.pdfIn PDF document text
    • https://agriplan-rs.com/dados/ckfinder/files/14344270281.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/fzgW7-mxBc0/uplcv?utm_term=barreras+para+el+aprendizaje+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_off0000e5cd.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE5CD 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_01_sfnt_off0000fde4.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xFDE4 10516 bytes
SHA-256: e9f3f361e380571f4b37f8807bfb0a5cedf83ccb816d6a0194c71241751406a1
font_02_sfnt_off000115e3.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x115E3 20068 bytes
SHA-256: 3162dfa61a4bdae88931b4059c1bcf933f23084622ba1b0340259cdfd7e219b5