Malicious PDF — malware analysis report

Static analysis result for SHA-256 71bf8c88ec868d82…

MALICIOUS

PDF

76.7 KB Created: 2021-09-19 19:50:30 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-27
MD5: e88fe0f200eff845edf327fa42687c7a SHA-1: 3d493a554fc94940b08f1449831512dc55e623cd SHA-256: 71bf8c88ec868d82ef5b2fad6166847d06addb6f40404052c548006d87e20248
156 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The PDF file was flagged by ML classifiers and ClamAV as malicious. Heuristics indicate it contains a link farm pointing to compromised WordPress upload storage, a common technique for distributing malicious content or phishing lures. The presence of multiple unknown URLs and the nature of the heuristics suggest a phishing or malware distribution campaign.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9989

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 https://www.olympusnorge.no/wp-content/plugins/super-forms/uploads/php/files/ukrt8qua9mkur157tsd5q6gt4d/32833374366.pdf In PDF document text
    • https://binhvi.com/upload/files/74133141414.pdfIn PDF document text
    • https://jjcfurnituremaker.com/userfiles/files/71227902783.pdfIn PDF document text
    • https://khoahoc.timviec365.com/picturesfiles/keragafikiriboliwegol.pdfIn PDF document text
    • https://ashleymongolia.mn/uploads/files/86842224272.pdfIn PDF document text
    • https://kaowei.tw/image/files/20210901_195151.pdfIn PDF document text
    • http://unibeauty.com.br/ckfinder/userfiles/files/7221391220.pdfIn PDF document text
    • https://lllk.ru/wp-content/plugins/super-forms/uploads/php/files/53235ecd236d8dbde1697b4113c00957/dupuvuruxuwekav.pdfIn PDF document text
    • https://ocvirapuato.com.mx/wp-content/plugins/super-forms/uploads/php/files/625fa9b5b5a0836427b16a88e7a8ce6b/11772305137.pdfIn PDF document text
    • http://www.eurosecurimed.com/ckfinder/userfiles/files/57691069259.pdfIn PDF document text
    • https://parisautotravel.com/wp-content/plugins/super-forms/uploads/php/files/8o00ehmoa7k2rg30u87rhri536/razujiwasekiwuziduwidi.pdfIn PDF document text
    • https://mobilaide.com/upload/editor/file/rukunura.pdfIn PDF document text
    • http://tjsyjdq.com/v15/Upload/file/2021951145411727.pdfIn PDF document text
    • https://majubesar.info/contents/files/dunudutuw.pdfIn PDF document text
    • http://ladna.pl/user_images/file/64879740415.pdfIn PDF document text
    • http://www.dean-cpa.com/files/adminpic/file/ragawegebex.pdfIn PDF document text
    • https://mavachhaiphong.com/upload/files/59345860324.pdfIn PDF document text
    • https://fuoriscena.eu/file/gunisubinute.pdfIn PDF document text
    • https://tidymoney.com/ckfinder/userfiles/files/63858734650.pdfIn PDF document text
    • https://birsamundapark.in/userfiles/files/suramepobomixonetitu.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/BkSY9tpko7c/uplcv?utm_term=big+farm+offline+game+downloadPDF 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_off0000c7b1.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xC7B1 17512 bytes
SHA-256: e1a71f7b5ea75f46105e8ea4388b2ccd415ce28c1488bce17c3914fea0cdd451
font_01_sfnt_off0000f54e.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF54E 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off00010d65.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x10D65 10568 bytes
SHA-256: 4f4d916d7f1816557bbe7540ce07dace7ce4a910e4bb7648987002d4e4ac0e50