Malicious PDF — malware analysis report

Static analysis result for SHA-256 a5cafd7c27d3c5e9…

MALICIOUS

PDF

71.2 KB Created: 2021-10-07 14:07:46 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3)
MD5: 8302113914589c44d0b7a829ea16ba7c SHA-1: 6a31b17281fd3cb95aa7f588f13e07f8de8afc2d SHA-256: a5cafd7c27d3c5e9948348847df642fbbed0e41ae52d6f2c0172926cc7de6745
126 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The PDF contains numerous embedded URLs, many of which are part of link farms hosted on disposable domains, indicating a phishing or malware distribution attempt. The ML classifier and ClamAV detection strongly suggest malicious intent. While no scripts were explicitly extracted, the PDF structure and embedded URIs are consistent with techniques used to redirect users to malicious sites, likely for credential harvesting or further payload delivery.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9916

Heuristics 5

  • ClamAV: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0
  • 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://krisoc.ru/uplcv?utm_term=less+desirable+meaning
    • http://thepducphat.com/upload/files/zuvowatoforukunav.pdf
    • https://t2sc.me/userfiles/mepomiluxegifuzoj.pdf
    • https://ckfinder.pamlskovnik.cz/ckfinder/userfiles/files/lizozuxukubudagajuzi.pdf
    • http://kaizenlife.com/ckfinder/userfiles/files/85529132838.pdf
    • http://naphotelbangkok.com/userfiles/files/56030108686.pdf
    • https://questyme.com/userfiles/file/81678974192.pdf
    • http://cuanhavesinh.com/userfiles/file/28372224501.pdf
    • http://sellmysayarah.com/userfiles/files/lawup.pdf
    • http://klm-co.ru/foto/ck/files/noredakaziwibesafowixase.pdf
    • http://uran-berlin.com/userfiles/file/63935085873.pdf
    • http://clinicaveterinariasangiacomo.it/userfiles/files/zexilefotaxuwipa.pdf
    • https://ntpuvoice.com/ckfinder/userfiles/files/91261987842.pdf
    • http://clingac.com/d/files/kesidivinejupujimuso.pdf
    • http://abbeytraining.net/userfiles/file/96032162272.pdf
    • https://sscs-uae.com/userfiles/files/tozomoxopizikezagizupep.pdf
    • http://fygl.net/uploads/file/040033012836.pdf
    • http://amsasecretariat.fr/userfiles/file/fejib.pdf
    • http://minhquoc.vn/ckfinder/userfiles/files/nezepodujiketiribiva.pdf
    • https://extractos.assaludips.com/Proyectos_PHP/gestor/images/file/22812931560.pdf
    • http://tieuhocsondong.hoaiduc.edu.vn/ckfinder/userfiles/files/13943114447.pdf
    • http://recviem.ru/img/upload/wobuxobofib.pdf
    • https://xn--b8qxb801j.tw/upload/files/51728322692.pdf
    • https://aiwcecckolkata.org/FCKeditor/file/29243296856.pdf
    • https://k85shj16h-561lt.com/contents/files/kagezabel.pdf
    • http://wenxuezj.com/images/File/65152542147.pdf
    • https://studioconcept-stand.com/fck_userfiles/file/4085535603.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_off0000b827.bin
95712dae3b53b27643e035b638d31c601a1edf59ac47f835bb6531c2aa5d4fe3		 pdf-font-stream PDF embedded font (sfnt) at offset 0xB827 10472 bytes
font_01_sfnt_off0000cf94.bin
ad7129379a70aa30f4fc3b15acc81b6f4107ce68ecff7ace95c6f3e4eeeb67b4		 pdf-font-stream PDF embedded font (sfnt) at offset 0xCF94 15572 bytes
font_02_sfnt_off0000f6d0.bin
9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1		 pdf-font-stream PDF embedded font (sfnt) at offset 0xF6D0 16792 bytes

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