Malicious PDF — malware analysis report

Static analysis result for SHA-256 fe8dad5108b00923…

MALICIOUS

PDF

85.3 KB Created: 2021-09-13 10:07:19 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-11-03
MD5: 53d66d121807b990e30cead2c85be355 SHA-1: 558211a5ec73353081af4590d8f2f4c259f0fb1b SHA-256: fe8dad5108b0092375b9648bd54002cf318dd43bf1c728cda450b41e3a5168e1
126 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The sample is a PDF file flagged by ML classifiers and ClamAV as malicious. It contains numerous embedded URLs pointing to other PDF files, indicating a link farm or distribution network. The PDF_SEO_DISPOSABLE_LINK_FARM heuristic specifically calls out this behavior. While no scripts were directly extracted, the nature of PDF exploitation often involves embedded JavaScript for malicious actions, hence the inclusion of T1059.007.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9973

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://www.brunosistemi.com/wp-content/plugins/formcraft/file-upload/server/content/files/1613eee9b8d7e6---vejidosadozowib.pdf In PDF document text
    • http://goodlack.cz/userfiles/file/21871401106.pdfIn PDF document text
    • http://jinyudachem.com/upload/files/jizanejazutid.pdfIn PDF document text
    • http://surausa.com/uploads/files/74154139652.pdfIn PDF document text
    • http://www.pvvc.cz/files/82110442211.pdfIn PDF document text
    • http://dasbluemchen.com/ziwidimebujigubokedo.pdfIn PDF document text
    • https://jogamiskolc.hu/ckfinder/userfiles/files/29045774974.pdfIn PDF document text
    • https://pametnidom.hr/pametne_kuce/userfiles/file/jujoni.pdfIn PDF document text
    • https://snqrsl.quebec/upload/editor/file/24732487868.pdfIn PDF document text
    • http://streetnn.ru/data/upload/ck/files/85713970763.pdfIn PDF document text
    • http://bertrandetgastineaudesigners.fr/userfiles/file/95288993752.pdfIn PDF document text
    • https://styliststudios.com/imagesTE/file/37865179910.pdfIn PDF document text
    • http://kajo-frings.de/userfiles/file/kimubomigefuxularan.pdfIn PDF document text
    • https://eniedu.com/data/file/20210911200831.pdfIn PDF document text
    • http://oticonshop.com/ckfinder/userfiles/files/72417406299.pdfIn PDF document text
    • http://rkenterprisesonline.com/FCKeditor/file/1602953050.pdfIn PDF document text
    • http://sprinter-lab.ru/content/File/47782040061.pdfIn PDF document text
    • http://playbabydoll.com/userfiles/file/69847983466.pdfIn PDF document text
    • http://chanakyaaerospacedefence.com/userfiles/file/xesikokonejijaza.pdfIn PDF document text
    • https://windsbs.biz/files/file/nufejenosi.pdfIn PDF document text
    • http://xinge168.com/uploads/files/20210905135533_431823.pdfIn PDF document text
    • https://nstoplana.rs/ckfinder/userfiles/files/buparajoguwox.pdfIn PDF document text
    • https://www.helpfulhunks.com.au/wp-content/plugins/formcraft/file-upload/server/content/files/161341e92c5ca3---nutedizonetirowajeri.pdfIn PDF document text
    • https://feedproxy.google.com/~r/1eyvgo/aqOO/~3/zMnd8XtcwSM/uplcv?utm_term=android+app+exchange+servicesPDF link annotation
    • 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_off0000f001.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF001 10796 bytes
SHA-256: 49b518db5341b4b818ebb064de96b822d52017c489a5f799f0398da029412eb2
font_01_sfnt_off0001089c.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x1089C 17460 bytes
SHA-256: 67b9b2b321f1435c47067dbc34b1def70d8e8ac9a63f25c79df986c97e419e57
font_02_sfnt_off00013621.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x13621 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1

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