Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 e7dceea9f2d8680d…

MALICIOUS

RTF / .DOC

1.64 MB First seen: 2022-05-03
MD5: 375da39b3b3dc136d7d915b975ebba9b SHA-1: b630fd528392290a397709ef39c89371b61bcad6 SHA-256: e7dceea9f2d8680dabc0ebac9649188d4b1ecf0191705758eeb949cf7342b6df
180 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The file is an RTF document containing an embedded OLE object that exploits the Equation Editor vulnerability (CVE-2017-11882). The ".objupdate" directive forces the activation of this object, which in turn executes a malicious script. The script appears to be designed to download and execute a second-stage payload, indicated by the presence of VBA code and the nature of the exploit.

Heuristics 5

  • Equation Editor activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED
    RTF decodes to an Equation.3 ProgID and requests OLE activation with \objemb plus \objupdate. This reaches the legacy Equation Editor attack surface used by CVE-2017-11882/CVE-2018-0802 documents, but the malformed MTEF/native payload needed for stronger 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.
  • OLE object data medium RTF_OBJDATA
    RTF contains 2 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000012c5.bin
748ae9e3f1e279803251c414721425d1b4fc19ecd3cf62243447e23c355b69da		 rtf-objdata-decoded RTF \objdata at offset 0x12C5 86002 bytes
objdata_01_off00036c32.bin
c7f66a5092004b086e30607399e53188f400669ce12663293bd5d8efa0ef2bda		 rtf-objdata-decoded RTF \objdata at offset 0x36C32 356207 bytes

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