Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 b1c717c9b9e7a0f2…

MALICIOUS

RTF / .DOC

1.96 MB
MD5: 24c529c42fd601c08e60ca5d8d1d8e93 SHA-1: 11adecb55c766104c46e7cac2a294826c768d1eb SHA-256: b1c717c9b9e7a0f288037eae7f0d1ce5b9e6ffce000172fd5df85997ecfa59d4
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The RTF file contains embedded OLE objects, specifically triggering the CVE-2017-11882 vulnerability through the Equation Editor. The ".objupdate" directive forces the activation of this embedded object, leading to the execution of a malicious payload. The decoded object data contains what appears to be obfuscated VBScript, likely responsible for downloading and executing a second-stage payload.

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_off00001116.bin
8564c57b669565870ec4fc8fe55abd5219673e3c381f22987243365ee7c433f9		 rtf-objdata-decoded RTF \objdata at offset 0x1116 25552 bytes
objdata_01_off0001917d.bin
ac9bfb081d4e3f91c1d530b09d33124ea631b81e03f3efc0b3eee9f29b094bb3		 rtf-objdata-decoded RTF \objdata at offset 0x1917D 463381 bytes

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