Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 721e1b0baf301522…

MALICIOUS

RTF / .DOC

1.98 MB First seen: 2021-09-27
MD5: d31b0307a56355711e50f3b58856b86b SHA-1: 679f702616c0b9cbdad437c00b26614084acb322 SHA-256: 721e1b0baf30152244af380c4140ef5b4145dd73c133b1e118c76cc224cb6519
220 Risk Score

Malware Insights

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

The RTF file contains OLE object data and specifically triggers heuristics related to CVE-2017-11882, indicating exploitation of the Equation Editor vulnerability. This technique is commonly used to deliver a secondary payload, likely a malicious executable, to the victim's system.

Heuristics 5

  • Equation Editor OLE1 native payload — CVE-2017-11882 related critical CVE related CVE_2017_11882_RELATED
    RTF decodes to an OLE1 Equation.3 embedded object whose native data is large and payload-like, and \objupdate requests automatic activation. This is the delivery shape used by Equation Editor RCE documents such as CVE-2017-11882/CVE-2018-0802, but the malformed MTEF record needed for exact attribution was not recovered.
  • Split hex Equation Editor ProgID + OLE object critical RTF_EQUATION_EDITOR
    RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
  • \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.
  • Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX
    RTF contains ~2075KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    RTF contains 2 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000000e9.bin
0b777ab41b6795213d177c0f1a432131fb6ab64efe3c684d793624321a04696e
rtf-objdata-decoded RTF \objdata at offset 0xE9 1037939 bytes