Malicious PDF — malware analysis report

Static analysis result for SHA-256 21dfaff0f97c2e68…

MALICIOUS

PDF

88.8 KB Created: 2021-09-21 15:31:15 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-16
MD5: cae24ffc4b3835fdb9c2cc58fecd80bd SHA-1: dc285a199dbab9fa0709ccaa452e0f6730541ca8 SHA-256: 21dfaff0f97c2e6821375616e95c04fd9fbad2fabc1ccae0fa6990d148d2ab3b
156 Risk Score

Malware Insights

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

The sample was identified as malicious by ClamAV and an ML classifier, indicating a high likelihood of malicious intent. Heuristics reveal it functions as a link farm, with many URLs pointing to potentially compromised or disposable hosting, suggesting a phishing or malware distribution scheme. The presence of multiple PDF-specific heuristics related to external URIs and link farms further supports this assessment.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9983

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://ckfinder.pamlskovnik.cz/ckfinder/userfiles/files/xenebeb.pdf In PDF document text
    • http://crmloccitanecr.com/campannas/file/kazosuzafiwezekaliji.pdfIn PDF document text
    • http://alpinist.store/sribati/editor/uploadfiles/66673602490.pdfIn PDF document text
    • http://weighlessthisyear.com/ckfinder/userfiles/files/bilojozuzunazowudakowe.pdfIn PDF document text
    • https://flcevent.fcu.edu.tw/plugin/ce1/ckfinder/userfiles/files/20210908171708.pdfIn PDF document text
    • http://itemclinicchina.com/ckupload/files/ropowimis.pdfIn PDF document text
    • http://thy-environment.com/userfiles/files/85474021051.pdfIn PDF document text
    • http://www.nuricomuvakfi.org/wp-content/plugins/super-forms/uploads/php/files/l5jh1bhumbh8p762r1urnm7qc4/nukupejilo.pdfIn PDF document text
    • http://puzynowska-kancelaria.com/userfiles/file/82186707371.pdfIn PDF document text
    • http://mikailang.com/userfiles/file/20210915180339_672804890.pdfIn PDF document text
    • https://nobleanimalsanctuary.org/wp-content/plugins/super-forms/uploads/php/files/tmp/nuridokomun.pdfIn PDF document text
    • https://funke.be/data/file/16836633295.pdfIn PDF document text
    • https://muahohangnhat.com/app/webroot/uploads/files/27157342841.pdfIn PDF document text
    • http://chingyi.tw/userfiles/files/50015660758.pdfIn PDF document text
    • http://benetworkingpro.com/ckfinder/userfiles/files/63023877801.pdfIn PDF document text
    • https://zibarajabi.com/cache/fck_files/file/58012907766.pdfIn PDF document text
    • http://www.bc-arman.kz/ckfinder/userfiles/files/3982902429.pdfIn PDF document text
    • http://gamebonda.com/ckupload/files/13260800093.pdfIn PDF document text
    • http://neodev.space/wp-content/plugins/formcraft/file-upload/server/content/files/1613c205a9a65a---fukutilasurekuf.pdfIn PDF document text
    • https://andymullinscommercial.com/home/andy/public_html/ckfinder/userfiles/files/wuzagabetazuzagowuromepe.pdfIn PDF document text
    • http://birdwatching.sk/media/file/62323457103.pdfIn PDF document text
    • http://nedvizhimost-v-sharm-el-sheikhe.ru/uploads/files/50211040568.pdfIn PDF document text
    • http://colorfulmedia.de/fotki/fotki/file/fuguzubamepot.pdfIn PDF document text
    • http://kanoonkaraj.ir/dbmanager/filebank/htmlgallery/file///witunojubezol.pdfIn PDF document text
    • https://feedproxy.google.com/~r/1eyvgo/aqOO/~3/BkSY9tpko7c/uplcv?utm_term=call+recorder+magiskPDF link annotation
    • 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_off0000f4de.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF4DE 10632 bytes
SHA-256: df3e49289d786abe0f0e0bbf0cffa2c0bf19293c97c3c2ba6b31e42fa529f5be
font_01_sfnt_off00010d00.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x10D00 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off00012512.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x12512 18648 bytes
SHA-256: cf06e9b5e8c65fba8137357ee2addfd3d787dd348495751fe704f816d1f99f9a

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