Malicious RTF — malware analysis report

Static analysis result for SHA-256 0b38f8c35e851f82…

MALICIOUS

RTF

1.82 MB First seen: 2021-06-30
MD5: 0e0e5c21f5d17e1e452398502d11854e SHA-1: 296ea9d3e8023939942e9b3075430526c4010f17 SHA-256: 0b38f8c35e851f828b3bb3eef8c4aa237336003ea1a3096b862683aee99634be
180 Risk Score

Malware Insights

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

The RTF document contains embedded OLE objects, specifically triggering the CVE-2017-11882 vulnerability related to Equation Editor. This exploit is designed to execute arbitrary code, likely as a payload delivery mechanism. The presence of the Equation Editor ProgID and the ".objupdate" directive strongly indicate an attempt to leverage this known vulnerability for initial execution.

Heuristics 5

  • Split hex Equation Editor ProgID + OLE object critical CVE likely 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.
  • 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.
  • \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_off000011e1.bin rtf-objdata-decoded RTF \objdata at offset 0x11E1 53492 bytes
SHA-256: df373bbf12ef9eefaa8921bede21d7e7b66a84816c2d930db59ad44843139aa0
objdata_01_off0002ee39.bin rtf-objdata-decoded RTF \objdata at offset 0x2EE39 469226 bytes
SHA-256: 7d01ee387216102daeabf80a57c8f0d8112fdee1d8864b417a3fb9d69aa1d0dd

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