Malicious PDF — malware analysis report

Static analysis result for SHA-256 98937dc88c87cda3…

MALICIOUS

PDF

74.3 KB Created: 2021-09-04 21:22:35 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-05
MD5: 577b72c2970454e6c0f13c5372f488a2 SHA-1: 439f8ef0ebc29a09468e143bcb5b133844556ea3 SHA-256: 98937dc88c87cda3c4a22b3e248a9df77cfd609bb7521489cb4f4df0577436ab
156 Risk Score

Malware Insights

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

The PDF file was identified as malicious by a ClamAV signature and an ML classifier. Heuristics indicate it functions as a link farm, directing users to multiple distinct hosts, some of which are hosted on compromised CMS upload storage. 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 0.9973

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://cautrucpalang.vn/webroot/img/files/zelapisixeratat.pdf In PDF document text
    • https://chulintemple.org/CKEdit/upload/files/68837526102.pdfIn PDF document text
    • http://studiotravenzolo.it/userfiles/files/48739898368.pdfIn PDF document text
    • http://china-baby-clothes.com/d/files/vadebopozugavupuduxuf.pdfIn PDF document text
    • http://lorichphoto.com/pictures/file/37434094129.pdfIn PDF document text
    • http://chromavials.com/d/files/61894170.pdfIn PDF document text
    • http://pc-driver.ru/userfiles/files/7162681846.pdfIn PDF document text
    • https://elitestrategyglobal.com/wp-content/plugins/super-forms/uploads/php/files/b555940e9ae6f54a38950240547ea58d/68690345122.pdfIn PDF document text
    • http://360mart.net/uploads/files/mujudipagopelinetupo.pdfIn PDF document text
    • https://wamsconference.com/wp-content/plugins/super-forms/uploads/php/files/afa1dc5967cf4da3e0f22cf2dddc6dfa/49460102496.pdfIn PDF document text
    • https://mandalaconfeccao.com.br/wp-content/plugins/formcraft/file-upload/server/content/files/1607b098681b5c---82876902446.pdfIn PDF document text
    • https://amkboiler.com/wp-content/plugins/super-forms/uploads/php/files/q8ngpu0bhsrf0un3t1qaeb9kfk/megigas.pdfIn PDF document text
    • https://howardsteeves.com/wp-content/plugins/super-forms/uploads/php/files/6796b57eff5f5d6995a631356dd27143/18276710789.pdfIn PDF document text
    • http://iehyun.com/editorupload/file/divatelopalexanizod.pdfIn PDF document text
    • https://atlanthealth.com/wp-content/plugins/super-forms/uploads/php/files/ae714b8db40b65b2845498d9885ccc7b/8779966870.pdfIn PDF document text
    • http://afgventuregroup.com/cfiles/file/sisekibege.pdfIn PDF document text
    • https://www.drserapkagan.com/wp-content/plugins/super-forms/uploads/php/files/etpd70jt39k0aq16nced28d706/59655443547.pdfIn PDF document text
    • https://tcufroghouses.com/wp-content/plugins/formcraft/file-upload/server/content/files/16073625a164dd---14161864044.pdfIn PDF document text
    • http://www.hypnotiseur.com/wp-content/plugins/formcraft/file-upload/server/content/files/16083b11a3abc7---xiviwawixilewin.pdfIn PDF document text
    • http://myexamadvisor.com/fck_uploads/files/dizajiwajepifajejuviwaka.pdfIn PDF document text
    • https://estidevelopers.com/wp-content/plugins/super-forms/uploads/php/files/05ba6bc33c7022d271a29d9044509f20/kivepepilopeluk.pdfIn PDF document text
    • http://abroadster.com/files/8515708905.pdfIn PDF document text
    • http://www.siscard.com/wp-content/plugins/formcraft/file-upload/server/content/files/16080bac62214e---dowubakogabexumini.pdfIn PDF document text
    • http://alphabodysupplements.com/newerac2c/userfiles/file/84230211736.pdfIn PDF document text
    • https://feedproxy.google.com/~r/1eyvgo/aqOO/~3/BvfzZFkJO3s/uplcv?utm_term=roles+of+entrepreneurship+in+economic+development+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_off0000c2cc.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xC2CC 10932 bytes
SHA-256: 75ead2de086476848a85d39703c8a5f9afd91e0ce5d4c1fb597b8b0b451177d4
font_01_sfnt_off0000dbf7.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xDBF7 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off0000f409.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF409 15408 bytes
SHA-256: 9af9a5b8348b3803512d72482c431381f6fafb00d83cf9ab654e30e76feb7c24