Malicious RTF — malware analysis report

Static analysis result for SHA-256 a813de835de1b0f7…

MALICIOUS

RTF

7.9 KB Authoring application: Riched20 6.3.9600 First seen: 2018-09-04
MD5: de111f5702e06d3ad3f303bb6a0cf35e SHA-1: 29618d7e64d6b6cc55612ea436c0215570fa77c9 SHA-256: a813de835de1b0f7eb44600fe86ecd7836e65eca8b1ecfd46b1ce3a8cd1ee635
320 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains an embedded OLE object that leverages the CVE-2017-11882 vulnerability in Microsoft Equation Editor. This exploit allows for arbitrary code execution upon opening the document, likely as a means to deliver a secondary payload. The presence of the Equation Editor CLSID and specific object class further confirms this attack vector.

Heuristics 7

  • Equation Editor CLSID critical CVE likely RTF_EQUATION_EDITOR
    Equation Editor OLE CLSID found inside an OLE object — exploited by CVE-2017-11882 / CVE-2018-0802 / CVE-2018-0798
  • CVE-2017-11882 — Equation Editor FONT record overflow critical CVE likely CVE_2017_11882
    Equation Editor MTEF contains an overlong FONT typeface field, the vulnerable copy primitive for CVE-2017-11882. This is stronger evidence than the Equation Editor CLSID alone because it identifies the malformed record that drives code execution in EQNEDT32.EXE.
  • ClamAV: Rtf.Exploit.CVE_2017_11882-6584355-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Exploit.CVE_2017_11882-6584355-1
  • Equation Editor object class critical RTF_OBJCLASS_EQUATION
    Object class 'equation.3' references Equation Editor
  • \objupdate forces OLE activation high RTF_OBJUPDATE
    RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
  • OLE object data medium RTF_OBJDATA
    RTF contains 1 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000100.bin rtf-objdata-decoded RTF \objdata at offset 0x100 3546 bytes
SHA-256: b23848f9a58c495346fa6b87f33b745bcb68fdf78684dffacc16b437681ce0a4

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