Malicious PDF — malware analysis report

Static analysis result for SHA-256 6cb104e9fdf4c8f9…

MALICIOUS

PDF

80.2 KB Created: 2021-09-06 16:45:42 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-27
MD5: c591ddae379970334c5a7012c103ac9b SHA-1: e46039135d733a731e1e005d2232b6a1c8b679c7 SHA-256: 6cb104e9fdf4c8f9581e349e8e5925c2c2675c729afd0f4e09c12c52d122c95e
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. It contains numerous external URIs and links to compromised CMS uploads and disposable hosting, indicating a link farm designed to redirect users to malicious sites. 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://inwebjor.ru/uplcv?utm_term=coefficient+of+determination+worksheet+pdf PDF link annotation
    • http://aktifithalat.com/resimlerfiles/vezetaviwatalus.pdfIn PDF document text
    • http://xn--80ackbssfuieecff0e8c.xn--p1ai/wp-content/plugins/super-forms/uploads/php/files/fcra0rekfgq4as2qfud70ru0j5/zabilexe.pdfIn PDF document text
    • http://ballmillfactory.com/d/files/830507492.pdfIn PDF document text
    • http://lowry-averyreunion.com/clients/c/c0/c0e4e7922159a76f956c19110b7bfeb7/File/fojolapuke.pdfIn PDF document text
    • http://jar-ted.pl/file/toziwigamasilefime.pdfIn PDF document text
    • http://websurin.net/UserFiles/File/debetatijag.pdfIn PDF document text
    • http://conservationenergy.com/wp-content/plugins/formcraft/file-upload/server/content/files/16085e7575a9b1---92984418319.pdfIn PDF document text
    • https://www.vibrationmonitoring.asia/wp-content/plugins/formcraft/file-upload/server/content/files/160a33961ebfb7---59559483035.pdfIn PDF document text
    • https://www.beewellrx.com/wp-content/plugins/super-forms/uploads/php/files/tmp/gexajalosojesewofu.pdfIn PDF document text
    • http://hichipper.com/hichipper/uploadfile/file/2021082006001273499.pdfIn PDF document text
    • http://ecbpolska.pl/wp-content/plugins/super-forms/uploads/php/files/dd263f217118ff6d83bc5b0831f78a08/deveb.pdfIn PDF document text
    • http://asirius.su/wp-content/plugins/super-forms/uploads/php/files/4c9c275e9734b862b06e88ab89aa7303/17868480511.pdfIn PDF document text
    • http://nakajima-ya.com/upload/save_image/files/sapodutirufikisitobox.pdfIn PDF document text
    • http://studiopignotti.it/userfiles/files/mezes.pdfIn PDF document text
    • http://bahtiyardishekimi.com/fckfiles/file/98073749853.pdfIn PDF document text
    • https://lotte-ppta.com/beta/assets/file/67282771787.pdfIn PDF document text
    • http://www.peritaonline.es/ckfinder/userfiles/files/97074578634.pdfIn PDF document text
    • http://clinivetmadonnadirosa.eu/userfiles/files/ginatafodixetizapefafun.pdfIn PDF document text
    • https://www.colegiodesafio.net/home/wp-content/plugins/formcraft/file-upload/server/content/files/1607b3b24a5032---wigisudifepogo.pdfIn PDF document text
    • http://wo-kop.pl/userfiles/file/13341390433.pdfIn PDF document text
    • http://armanetti.com/images/42557703114.pdfIn PDF document text
    • http://rszm88.com/upfolder/e/files/20210530015555.pdfIn PDF document text
    • https://lmbri.com/WYSIWYGImage/file/66445773955.pdfIn PDF document text
    • https://webmakler.org/userfiles/file/budawatusasitipikazorowij.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_off0000d13d.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD13D 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_01_sfnt_off0000e94f.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE94F 18388 bytes
SHA-256: 075c00050a35178be2fa56673d83a727724480c7f0e931f8eb477f9aaf336701
font_02_sfnt_off0001196e.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x1196E 11048 bytes
SHA-256: c8cc86f0046822fd9e78b6ac7dcfbdb882e8cf8477198acd5d09dbe4d185ee63

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