Malicious PDF — malware analysis report

Static analysis result for SHA-256 81913861c60c8f9b…

MALICIOUS

PDF

89.0 KB Created: 2021-09-19 11:58:09 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-11-25
MD5: 444e6aa4bbcab856ac2ff7691b9d0714 SHA-1: d33a636f8e95226cfccb0f42340bd0decb1c7411 SHA-256: 81913861c60c8f9b66d76aa71c489e501539248ea71235aed5a114cb5147e1c3
126 Risk Score

Malware Insights

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

The PDF file was flagged by a machine learning classifier and ClamAV as malicious, indicating a high likelihood of malicious intent. Heuristics identified it as a link farm, with numerous embedded URLs pointing to other PDF files, suggesting a tactic to manipulate search engine results or distribute further payloads. The document body was unreadable, but the presence of multiple PDF links and the ML/ClamAV detections strongly suggest a malicious distribution or SEO poisoning campaign.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9973

Heuristics 5

  • ClamAV: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0
  • 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://www.hussco-steel.com/husscofiles/files/ponivigodebuvub.pdf In PDF document text
    • http://badischer-kunstverein.de/ckfinder/userfiles/files/dotokariwetufejapijisutaw.pdfIn PDF document text
    • http://icaalliance.org/filespath/files/20210908195830.pdfIn PDF document text
    • https://orrizon.ru/images/file/bibuwuwamiraluxut.pdfIn PDF document text
    • http://an-ocn.ru/ckfinder/userfiles/files/84843379366.pdfIn PDF document text
    • https://nacituran.com/userfiles/file/jiwexefofosivulotavug.pdfIn PDF document text
    • http://newabel.com/ckfinder/userfiles/files/92276000958.pdfIn PDF document text
    • http://rancholasmonturaspremios.com/campannas/file/musozilalujatem.pdfIn PDF document text
    • https://globaltranslation.com/demo/global_translation/beta/userfiles/files/wejilenozuwogajez.pdfIn PDF document text
    • http://imreelectric.sk/uploads/file/19195007499.pdfIn PDF document text
    • http://99hospitalitygroup.com/ckfinder/userfiles/files/zazejuvelagapunired.pdfIn PDF document text
    • http://baobianhkhang.com/upload/files/64817275823.pdfIn PDF document text
    • http://climacom.eu/userfiles/files/kewukiganiridefapajidiw.pdfIn PDF document text
    • http://torremaggiore.sitmap.it/files/files/wofasivotamuxu.pdfIn PDF document text
    • http://softwaretesting.kr/club/data/userfiles/file/20210918032915.pdfIn PDF document text
    • https://riwg.in/userfiles/file/zigusosuzimibenar.pdfIn PDF document text
    • http://schodylux.pl/userfiles/file/2334811538.pdfIn PDF document text
    • http://yujinpharma.com/upload/files/4027508982.pdfIn PDF document text
    • https://lockerova.eu/admin/upload/documents/75706986587.pdfIn PDF document text
    • http://dalnoboy.net/data/filestorage/upload/files/mejepunepofixisumojiz.pdfIn PDF document text
    • http://shopgraeagle.com/ckeditor/uploads/files/kajediwebinipafobog.pdfIn PDF document text
    • https://unitytradecapital.com/ckfinder/userfiles/files/67298149318.pdfIn PDF document text
    • https://nsck-cykelmotion.dk/userfiles/file/35896778639.pdfIn PDF document text
    • https://wilsonbarrera.com/inicio/wp-content/plugins/formcraft/file-upload/server/content/files/161301d1f769b1---49509920797.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/fzgW7-mxBc0/uplcv?utm_term=how+to+mod+dragon+cityPDF 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_off0000f676.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF676 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_01_sfnt_off00010e88.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x10E88 18384 bytes
SHA-256: 664f7c72c20efb52b8367390e093b7082ab1b411eefa473a688286aa1d609c8c
font_02_sfnt_off00013e55.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x13E55 10556 bytes
SHA-256: 6d91e9407195aa4b348d3b469f5d4f7672de57160d514d2c8d044b61747a458b