Malicious RTF — malware analysis report

Static analysis result for SHA-256 9d5c59666878edc1…

MALICIOUS

RTF

265.4 KB First seen: 2019-04-18
MD5: 82901a43f403ed3de74dab050fcefb62 SHA-1: 4c519c47c85b01a549fd7cfc880ead678123fba0 SHA-256: 9d5c59666878edc1c08ed22712bc1049d894cbba2be9bcf184d33ee50e4ee458
160 Risk Score

Malware Insights

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

The sample is an RTF document that contains an embedded OLE object. Heuristic analysis indicates a critical vulnerability, CVE-2017-11882, related to Microsoft Equation Editor. This vulnerability is commonly exploited to achieve arbitrary code execution, typically to download and run a second-stage payload. The presence of ".objupdate" further suggests an attempt to trigger the OLE object's activation. Given the nature of the exploit, the initial access vector is likely spearphishing.

Heuristics 4

  • 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.
  • Automatically linked OLE object high RTF_OBJAUTLINK
    RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
  • \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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000ec4.bin rtf-objdata-decoded RTF \objdata at offset 0xEC4 4158 bytes
SHA-256: 8defc5c8a861db4f28692ff15fb6c41e079e76f34f046518234967bcafbc9e2b