Malicious PDF — malware analysis report

Static analysis result for SHA-256 a5cb3f65d51179eb…

MALICIOUS

PDF

78.5 KB Created: 2021-09-19 01:58:14 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-14
MD5: 96711b39ebe98810d39d6a2f1b0659c6 SHA-1: 69f032a4118a05f314dd8fb1b848ae67c2719934 SHA-256: a5cb3f65d51179ebba64a9e9c94e94a27b684405e358eb95e44c06b20f0d5fc9
156 Risk Score

Malware Insights

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

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 potentially compromised or disposable hosting sites. The document body is heavily obfuscated and unreadable, suggesting it's not intended for direct user interaction but rather to host links.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9846

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://opusbiz.kr/data/editor/file/1510803330614207159e1e4.pdf In PDF document text
    • http://ovstav.cz/app/webroot/files/files/nelepekik.pdfIn PDF document text
    • http://uteambio.com/upload/files/26098547935.pdfIn PDF document text
    • http://didongsinhvien.com/upload/files/vejojevujenobasu.pdfIn PDF document text
    • https://qwert5.com/psum/admin/userfiles/file/84068716808.pdfIn PDF document text
    • https://sacc-la-chaux-de-fonds.ch/fichiers/file/fuvizaroval.pdfIn PDF document text
    • https://syntellect.ru/Repository/file/72951635950.pdfIn PDF document text
    • https://howardsteeves.com/wp-content/plugins/super-forms/uploads/php/files/c69089b209822383a8996a0b1eb281ca/25234244261.pdfIn PDF document text
    • http://mwbright.com/upload_fck/file/2021-9-11/20210911082355622742.pdfIn PDF document text
    • http://perksys.com/userfiles/file/bubakovinafuw.pdfIn PDF document text
    • http://grubstreet.ca/ckfinder/userfiles/files/66104114699.pdfIn PDF document text
    • http://share-world.tw/userfiles/file/bedogukigemegonuv.pdfIn PDF document text
    • http://velocimapper.com/webfiles/file/73051024030.pdfIn PDF document text
    • https://stockbauer.hu/uploads/file/fivilimazefelel.pdfIn PDF document text
    • https://ljlconst.com/admin/images/file/lijirimemikalewegom.pdfIn PDF document text
    • http://sh-ruiyangcpa.com/userfiles/file/2021-9///2021941822133551.pdfIn PDF document text
    • http://xn--38-mlcqjbufcz6h.xn--p1ai/userfiles/file/82444931394.pdfIn PDF document text
    • https://1sis.com/wp-content/plugins/formcraft/file-upload/server/content/files/1612f334f7b201---supimob.pdfIn PDF document text
    • https://infravoip.com/wp-content/plugins/super-forms/uploads/php/files/1baefd93819c4503eb3cd655415f24e8/nalawesuwuduzikub.pdfIn PDF document text
    • https://www.whoamiandwhyamihere.com/ckfinder/userfiles/files/tapirek.pdfIn PDF document text
    • http://congseng.com/uploadfile/files/nojidopanabigabi.pdfIn PDF document text
    • https://mavismanagement.com/wp-content/plugins/formcraft/file-upload/server/content/files/1612f1668c952d---31360986289.pdfIn PDF document text
    • http://yangpupark.com/uploadfile/files/25028464618.pdfIn PDF document text
    • http://msci.com.ng/wp-content/plugins/formcraft/file-upload/server/content/files/161352074c7293---mulonilosuzebuzikujeto.pdfIn PDF document text
    • https://mobilieroccasion.fr/uploads/file/25418592692.pdfIn PDF document text
    • http://pekingtogo.com/uploads/files/wirabinuxibe.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/fzgW7-mxBc0/uplcv?utm_term=beyond+the+mountain+and+hills+watch+onlinePDF 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_off0000cda9.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xCDA9 10888 bytes
SHA-256: 3a2e71b8d45135db3c9608d8d3a76e5dfd1154eeb288975c9f7373665ee309b2
font_01_sfnt_off0000e6be.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE6BE 17368 bytes
SHA-256: 24cf7b389e52b60b6c303bfd672c89f24684b2b52a6a01a7b3e6db13c5047b1e
font_02_sfnt_off000113df.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x113DF 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1

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