Malicious RTF — malware analysis report

Static analysis result for SHA-256 251ba131ec5a971c…

MALICIOUS

RTF

9.1 KB First seen: 2019-05-31
MD5: ef831c07d25cbd7364db412750aef326 SHA-1: 13faca59aeae65c5c439d212a54b4a6377ba62a1 SHA-256: 251ba131ec5a971c2a6b0297cbcba4ffe0f01717f73b9d3a46dbf62d68268669
240 Risk Score

Malware Insights

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

The RTF file contains embedded OLE object data and specifically triggers heuristics related to the Equation Editor vulnerability (CVE-2017-11882). This exploit is known to allow for arbitrary code execution, likely to download and run a secondary payload. The presence of the ".objupdate" directive further indicates an attempt to force OLE object activation.

Heuristics 5

  • 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: Doc.Exploit.CVE_2017_11882-6934206-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Exploit.CVE_2017_11882-6934206-0
  • \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_off0000003b.bin rtf-objdata-decoded RTF \objdata at offset 0x3B 4650 bytes
SHA-256: 5537fbd202aea423485216c0a85c16cf31c1f51fa9ccd671922520e12ab9d982