Malicious PDF — malware analysis report

Static analysis result for SHA-256 9c44c0b9a4f44619…

MALICIOUS

PDF

71.4 KB Created: 2021-09-14 07:36:17 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-12
MD5: 4108a636a62d5b2c9f0e976202401a74 SHA-1: 6b926cd36ec883adb820d67b073d842e2cbc0313 SHA-256: 9c44c0b9a4f44619cbe5dacbd729ba503b6b80f43793fb04876e620886d58074
156 Risk Score

Malware Insights

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

The PDF file was detected as malicious by ML classifiers and ClamAV, indicating a high likelihood of malicious intent. It contains numerous embedded URLs, many of which point to domains flagged as compromised CMS uploads or disposable hosting, suggesting a link farm designed to redirect users to malicious sites. The document body is heavily obfuscated and appears to be generated by wkhtmltopdf, providing no direct user-facing content but likely serving as a container for these malicious links.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9986

Heuristics 6

  • ClamAV: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0
  • 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://medsplus.us/admin/images/file/wujaxofisetolawelew.pdf In PDF document text
    • http://sdes.in/uploads/31105113800.pdfIn PDF document text
    • http://balone.net/_upload/file///xogagefafisebagabivat.pdfIn PDF document text
    • http://www.jucadent.es/ckfinder/userfiles/files/rowivowibuvuromex.pdfIn PDF document text
    • https://liur-krd.ru/userfiles/file/komit.pdfIn PDF document text
    • https://relaxationplusmn.com/wp-content/plugins/super-forms/uploads/php/files/7958b29bf3ed59e624c6c9f2b84624ff/kusazasex.pdfIn PDF document text
    • http://nitexprofi.cz/userfiles/file/fuwox.pdfIn PDF document text
    • https://lidiyageorgieva.com/ckfinder/userfiles/files/47502061003.pdfIn PDF document text
    • http://www.hausbaumesse.at/ckfinder/userfiles/files/pexilewefulepixazu.pdfIn PDF document text
    • https://rougezenekar.hu/files/file/93306930094.pdfIn PDF document text
    • http://ccsup.co.th/uploads/ckfinder/files/lokeliruvapanezobul.pdfIn PDF document text
    • https://rafautama.com/uploads/file/bevupigafijivujunal.pdfIn PDF document text
    • http://philipsphotographystudio.com/16244208686.pdfIn PDF document text
    • http://klubbelgickychobrov.sk/editor_uploads/files/romosugunuvaparuriwezig.pdfIn PDF document text
    • http://mdknoodles.co/uploads/files/mujebud.pdfIn PDF document text
    • https://mauspro.net/upload/files/23334505353.pdfIn PDF document text
    • http://pc580.cn/upload_fck/file/2021-9-9/20210909172005967086.pdfIn PDF document text
    • http://bestorkate.com/uploads/ckeditor/files/93945809681.pdfIn PDF document text
    • https://uaqbakery.com/wp-content/plugins/formcraft/file-upload/server/content/files/1613d9f49d72c2---51510946581.pdfIn PDF document text
    • https://skyfireconsulting.com/wp-content/plugins/super-forms/uploads/php/files/tjsuuglno0332046ps3apl5f1c/41447238357.pdfIn PDF document text
    • http://soosanfix.com/upload/fckeditor/file/61387868874.pdfIn PDF document text
    • https://feedproxy.google.com/~r/skout/mBVl/~3/cv9VXjIrmdE/uplcv?utm_term=is+wrongly+a+wordPDF 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_off0000b783.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xB783 16308 bytes
SHA-256: 2bf83398a396cdd8e295b412e32a85d7ef1dac08669f53221d7c166fe63a85d9
font_01_sfnt_off0000e0fa.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE0FA 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off0000f911.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF911 10252 bytes
SHA-256: 3810c6427fc32afdd7b14be0c5c7660d70ed6c07ecc1576d59becca0d9a7962f