Malicious PDF — malware analysis report

Static analysis result for SHA-256 51b8cea5b1e139c4…

MALICIOUS

PDF

81.6 KB Created: 2021-09-10 21:32:25 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3)
MD5: 2d4b43b31f73cf76edec450561706cfb SHA-1: ee82f4d7c0d0c1a695a961f60f8a0885dbd4e02e SHA-256: 51b8cea5b1e139c4985df0aabe84224aa6b3dd478cf221c5db249809dba789ec
156 Risk Score

Malware Insights

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

The file is identified as malicious by ClamAV and an ML classifier, with heuristics indicating it functions as a link farm. Several extracted URLs point to compromised WordPress sites and disposable hosting, suggesting an attempt to redirect users to malicious content. The presence of 'utm_term' in one URL further supports a phishing or spamming intent.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9949

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://chcial.ru/uplcv?utm_term=pdf+xchange+viewer+free
    • https://djhelaly.com/wp-content/plugins/super-forms/uploads/php/files/54851cb97d71377845348b7031c4feee/wulutigixuvubuda.pdf
    • https://fedico.ca/upload/editor/file/rewuruwiriba.pdf
    • http://stlukesfp.org/ckfinder/userfiles/files/9359738351.pdf
    • https://hacunamatata.ru/wp-content/plugins/super-forms/uploads/php/files/02da411755b2c0bcb10a1627024e5a1e/12633951552.pdf
    • https://avis-medical.ma/wp-content/plugins/super-forms/uploads/php/files/a65a4583f6f445fe2cc7b46725b0b7df/zujejibitarol.pdf
    • http://flashdisplay.net/UploadFiles/FCKeditor/20210910022629.pdf
    • http://ablerexthailand.com/userfiles/files/limerazetoxebedogopo.pdf
    • http://chiaranannini.com/userfiles/files/92312443125.pdf
    • https://advantage.ee/media/contents/file/tokelusewuzakubaxoxo.pdf
    • http://texmet.pl/userimages/file/solep.pdf
    • https://costarica4d.com/contents/files/fisamosolovapek.pdf
    • http://bighost.vn/uploads/userfiles/file/60465915183.pdf
    • http://synhbio.com/upload/files/86353829373.pdf
    • http://euredit-editions.com/userfiles/file/punubagosibivasaxas.pdf
    • https://drhuanghair.com/uploads/files/202109072135356197.pdf
    • http://schouteninterieurwerk.nl/wp-content/plugins/formcraft/file-upload/server/content/files/1613430911bf70---94819970934.pdf
    • http://sumtinathholidays.com/admin/uploadfiles/file/35039672918.pdf
    • http://jgweld18.com/UploadFile/file/20210902222355957.pdf
    • http://amexeuro.com/an3_Uploads/file/tifoj.pdf
    • http://sparkpro.lv/content/file/31933019911.pdf
    • http://le-lemniscus-incandescent.fr/ckeditor/upload/files/gatiwuxivek.pdf
    • http://tndgdemo2.com/ckfinder/userfiles/files/luwubozelevoselamoz.pdf
    • https://firsatpin.com/calisma2/files/uploads/66485809772.pdf
    • http://simoncaulkin.com/images/vovujoz.pdf
    • https://holzhaus-suedtirol.it/wp-content/plugins/formcraft/file-upload/server/content/files/161354bc4a048c---zewevekop.pdf
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/pdf/1.3/
    • http://ns.adobe.com/xap/1.0/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/xap/1.0/rights/
    • http://dejavu.sourceforge.net
    • http://dejavu.sourceforge.net/wiki/index.php/License

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000da80.bin
9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
pdf-font-stream PDF embedded font (sfnt) at offset 0xDA80 16792 bytes
font_01_sfnt_off0000f292.bin
e1a89f748eafd1450aa6ceb14cb8d2be132c25298cbe01a4f68ea87952fb318a
pdf-font-stream PDF embedded font (sfnt) at offset 0xF292 17880 bytes
font_02_sfnt_off000120e7.bin
f9124dded26be47d11edc04e320082ae7b3a1aca6df707d059fe0f7adecd52e5
pdf-font-stream PDF embedded font (sfnt) at offset 0x120E7 10580 bytes