Malicious PDF — malware analysis report

Static analysis result for SHA-256 81813ca80139d2b3…

MALICIOUS

PDF

87.8 KB Created: 2021-09-11 06:07:05 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-27
MD5: 8a10139fbe4eb6cd0b662428184d5044 SHA-1: 645ed31c3102f4dfe2fd653c358da66caa53e884 SHA-256: 81813ca80139d2b31f043c9b316d8eaf22249aad6f23bf4ef9de58417d01feee
156 Risk Score

Malware Insights

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

The file was detected as malicious by ML classifiers and ClamAV, indicating a high likelihood of malicious intent. Heuristics identified it as a link farm, with many embedded URLs pointing to potentially compromised WordPress upload directories and other unknown hosts. This suggests the document's primary purpose is to redirect users to external sites, likely for phishing or to download further malicious content.

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 https://elicopter-de-inchiriat.ro/wp-content/plugins/formcraft/file-upload/server/content/files/161341ecfe3bfe---zinewaze.pdf In PDF document text
    • https://postelezmasivu-ostrava.cz/ckfinder/userfiles/files/17146821640.pdfIn PDF document text
    • https://rallstarawards.us/nbloom/fckuploads/file/ferebov.pdfIn PDF document text
    • http://clinicaveterinariasangiacomo.it/userfiles/files/motugetesufujabaxexa.pdfIn PDF document text
    • http://childconnect.com/swi/fckfiles/file/62688937278.pdfIn PDF document text
    • http://royalleasingny.com/admin/images/file/57871237234.pdfIn PDF document text
    • http://eskuvotoszkanaban.hu/editor_up/19716200542.pdfIn PDF document text
    • https://jdrum-music.com/uploads/ckfiles/files/sepajanova.pdfIn PDF document text
    • https://sanagustin.cl/files/dasawitisujefowejumedivap.pdfIn PDF document text
    • http://pc580.cn/upload_fck/file/2021-9-4/20210904230505601242.pdfIn PDF document text
    • http://chieucoingason.vn/files/69357614376.pdfIn PDF document text
    • http://www.airportlimofortlauderdale.net/wp-content/plugins/formcraft/file-upload/server/content/files/161360eeb1da77---90974344611.pdfIn PDF document text
    • https://bestcoloringpages.com/userfiles/file/limolejo.pdfIn PDF document text
    • http://www.thunderesp.com/ckfinder/ckfinder.htmlfiles/gofizetixoxota.pdfIn PDF document text
    • https://juniorclublivorno.com/sitonews/images_upload/files/55138748662.pdfIn PDF document text
    • http://pc75.net/upfiles/file/1631328921.pdfIn PDF document text
    • http://monarchiaerembolt.hu/tmp/jozepof.pdfIn PDF document text
    • https://xn----7sbabak5acz7byau.xn--p1ai/wp-content/plugins/super-forms/uploads/php/files/685300dccd388975353790760533795d/74466568892.pdfIn PDF document text
    • https://sluganarodu.org/userfiles/files/kiduxagaxu.pdfIn PDF document text
    • https://smartbrand.ro/mm/file/45113910284.pdfIn PDF document text
    • http://rioairporttransfer.com/ckfinder/userfiles/files/56894078941.pdfIn PDF document text
    • https://ijp2.com/contents/files/23258153366.pdfIn PDF document text
    • https://ecotranslation.ca/upload/editor/file/44308160832.pdfIn PDF document text
    • http://dj-venci.com/uploads/pages/files/luzepijanukegevi.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/cv9VXjIrmdE/uplcv?utm_term=how+to+close+background+apps+in+androidPDF 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_off0000f1a5.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF1A5 11100 bytes
SHA-256: 42ddd6a492a49c129d6806216ff2a5bd9cffb50c0909a52a4c57633281ee5b08
font_01_sfnt_off00010b3e.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x10B3E 17772 bytes
SHA-256: d35bbfb67fd535f45bcd07a118c306fa5fc7283a95b3f527de2fabbbac0b3378
font_02_sfnt_off00013926.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x13926 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1