Malicious PDF — malware analysis report

Static analysis result for SHA-256 623a6cb5d7fdafda…

MALICIOUS

PDF

83.5 KB Created: 2021-09-04 17:58:28 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-09-29
MD5: b1752e429f198a29ddf50a71de75a841 SHA-1: 9c5ac29252d4646855ef339c30075d332a96f74a SHA-256: 623a6cb5d7fdafdab79038957b1a0788dcc0b06352efd8a9c05736a4f6f5ac17
96 Risk Score

Malware Insights

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

The PDF file contains a large number of external URIs, many of which point to compromised WordPress installations. The ML classifier strongly indicated maliciousness. The document body is heavily obfuscated and unreadable, suggesting it's not intended for human consumption but rather to host links. The primary function appears to be acting as a link farm, potentially for SEO manipulation or to distribute further malicious content.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9981

Heuristics 5

  • 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://wastran.ru/uplcv?utm_term=heraclitus+seminar+heidegger+pdf PDF link annotation
    • https://proff-doors.ru/wp-content/plugins/super-forms/uploads/php/files/3d5101552056bcacfbf271ce5db0e018/fomopisukodozo.pdfIn PDF document text
    • http://metamorfoza-krosno.pl/userfiles/file/ragefavuziribifepazise.pdfIn PDF document text
    • http://www.1000ena.com/wp-content/plugins/formcraft/file-upload/server/content/files/160871ff54e1a1---71343804200.pdfIn PDF document text
    • https://synodradomski.pl/userfiles/file/9314934672.pdfIn PDF document text
    • https://xn--nmqu14inmf.com/upload/files/83066037038.pdfIn PDF document text
    • http://ahcxdq.com/uploads/file/272101466118.pdfIn PDF document text
    • http://martonaroniskola.net/userfiles/file/nebexagegi.pdfIn PDF document text
    • http://studiotecniconuti.it/userfiles/files/68972226494.pdfIn PDF document text
    • http://www.mtpartnersfl.com/wp-content/plugins/formcraft/file-upload/server/content/files/161291e0ae108a---51764293990.pdfIn PDF document text
    • https://betonwerkendejonge.nl/wp-content/plugins/formcraft/file-upload/server/content/files/1608b455ba33a8---darogi.pdfIn PDF document text
    • https://advik.net/userfiles/file/xuxetitepered.pdfIn PDF document text
    • https://luxmarketing.agency/wp-content/plugins/super-forms/uploads/php/files/d9ivku0suhm910h7ecdo6hm4et/51580665879.pdfIn PDF document text
    • https://www.ltgpartners.com/wp-content/plugins/super-forms/uploads/php/files/a039540bcfd3b2886b95989d57846962/nazizunopibakuzalivuzatoj.pdfIn PDF document text
    • http://21cedu.com/pds/userfiles/files/19663380188.pdfIn PDF document text
    • https://mfdesign.hu/files/file/90538161740.pdfIn PDF document text
    • https://akemi.ro/hirek/file/duxalazomelebaseg.pdfIn PDF document text
    • http://studioturina.com/userfiles/files/ladak.pdfIn PDF document text
    • https://www.adler-leitishofen.de/wp-content/plugins/formcraft/file-upload/server/content/files/1608066e1c71d2---97578936205.pdfIn PDF document text
    • http://kazenergy.kz/wp-content/plugins/formcraft/file-upload/server/content/files/1608e6934641e9---kovexir.pdfIn PDF document text
    • http://sp3siemianowice.pl/userFiles/files/xatiletewupelusopi.pdfIn PDF document text
    • http://rheumatology.institute/upload/content/file/pewawo.pdfIn PDF document text
    • https://www.ideakliniksisli.com/wp-content/plugins/formcraft/file-upload/server/content/files/160f578fb8fe70---dofuj.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_off0000e164.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE164 11036 bytes
SHA-256: 54ed88f11ba1545d0f0988f39efd9057f9326a77165858d51dc50daeb600d8df
font_01_sfnt_off0000fa8b.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xFA8B 17496 bytes
SHA-256: d680b8ae883ef4c9865ef8dcc75b46d43914225863ca9537df4685ccc57b76f1
font_02_sfnt_off000127ee.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x127EE 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1