Malicious PDF — malware analysis report

Static analysis result for SHA-256 c6724e0703507ed2…

MALICIOUS

PDF

80.0 KB Created: 2021-09-23 08:46:00 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-24
MD5: c00d02f392b446741e9382dcce782621 SHA-1: 267b99041b2cd14c13921c460a1f2a5df7a2e847 SHA-256: c6724e0703507ed2c365f1b7e75f9ea7a98b6a20f37a0afd426cb1ac8e518624
156 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious Link

The PDF file was flagged by a machine learning classifier and ClamAV as malicious, specifically as a phishing trojan. Numerous embedded URLs point to disposable hosting and compromised CMS upload directories, indicating a link farm designed to redirect users to malicious content. The document body is heavily obfuscated and appears to be generated by wkhtmltopdf, suggesting it's not intended for human readability but rather to host these malicious links.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9975

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://chcial.ru/uplcv?utm_term=codependent+no+more+pdf PDF link annotation
    • http://ipai-bg.eu/img/file/13534789148.pdfIn PDF document text
    • https://dimensioninteractive.com/WYSIWYGImage/file/81275622330.pdfIn PDF document text
    • https://www.hsbofmn.com/ckfinder/userfiles/files/xizozalekixugelulobu.pdfIn PDF document text
    • http://phulieumaymacbaoco.com/hinhanh_fckeditor/file/76329498946.pdfIn PDF document text
    • http://stonepigments.com/userfiles/file/29284515006.pdfIn PDF document text
    • http://analogsys.com/uploaded/file/1339271261319155445ea.pdfIn PDF document text
    • http://vinhthuanvietnam.com/upload/files/lajovotuvikukuzekeb.pdfIn PDF document text
    • http://espressobuilders.com/app/webroot/files/userfiles/files/85406154018.pdfIn PDF document text
    • https://nayyaralidada.net/alpha/ckfinder/userfiles/files/wewofikajetutesu.pdfIn PDF document text
    • https://ag-concept.ru/wp-content/plugins/super-forms/uploads/php/files/4ab249c977f20981c0eb6a7ab0489749/voreg.pdfIn PDF document text
    • http://ppogrimall.com/upload/editor_image/file/lakes.pdfIn PDF document text
    • http://konberdbio.com/upload/files/50509572694.pdfIn PDF document text
    • https://samsungklimalar.com/upload/ckfinder/files/43339041649.pdfIn PDF document text
    • http://theofficeplus.com/userfiles/file/kumoretuxi.pdfIn PDF document text
    • http://bagandpack.ru/wp-content/plugins/super-forms/uploads/php/files/0225f3939967ddc0f01cde69c6414b24/20793722821.pdfIn PDF document text
    • http://chinajnbt.com/images/upload/File/76138691333.pdfIn PDF document text
    • http://originalcheck.it/public/img_admin/file///23074806245.pdfIn PDF document text
    • https://virtualpulse.eu/UserFiles/file/258005107.pdfIn PDF document text
    • http://caacoding.net/wp-content/plugins/formcraft/file-upload/server/content/files/16144dd208b522---nilawovu.pdfIn PDF document text
    • http://xn--hy1bt45apoap01a.net/jangheung/userfiles/file/zagozu.pdfIn PDF document text
    • http://polipack.ru/content/file/fagozisojojolabufabokize.pdfIn PDF document text
    • 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_off0000d51f.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD51F 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_01_sfnt_off0000ed36.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xED36 10224 bytes
SHA-256: d77e154d17aeaf066d918b1a548d780a031f8cbdefc5ddc511e86add867eae2d
font_02_sfnt_off0001040f.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x1040F 18132 bytes
SHA-256: 4b96278fd29b22878e0d040c79c71871ae7ab6d819a1129f185d2fcecbffcd8a