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Update CVE-2017-11882.yar #440

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Update CVE-2017-11882.yar #440

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12 changes: 6 additions & 6 deletions cve_rules/CVE-2017-11882.yar
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Original file line number Diff line number Diff line change
Expand Up @@ -5,9 +5,8 @@
rule potential_CVE_2017_11882
{
meta:
author = "ReversingLabs"
reference = "https://www.reversinglabs.com/newsroom/news/reversinglabs-yara-rule-detects-cobalt-strike-payload-exploiting-cve-2017-11882.html"

author = "Hyeonu Chun"

strings:
$docfilemagic = { D0 CF 11 E0 A1 B1 1A E1 }

Expand All @@ -32,16 +31,17 @@ rule rtf_cve2017_11882_ole : malicious exploit cve_2017_11882 {
author = "John Davison"
description = "Attempts to identify the exploit CVE 2017 11882"
reference = "https://embedi.com/blog/skeleton-closet-ms-office-vulnerability-you-didnt-know-about"
sample = "51cf2a6c0c1a29abca9fd13cb22421da"
hash256 = "ff9bf989ddd0581391ab9bd9a669a7f76ee69335c96026486d5aec18938e98e6"
score = 60
//file_name = "re:^stream_[0-9]+_[0-9]+.dat$"
strings:
$headers = { 1c 00 00 00 02 00 ?? ?? a9 00 00 00 ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? 03 01 01 03 ?? }
$font = { 0a 01 08 5a 5a } // <-- I think that 5a 5a is the trigger for the buffer overflow
//$code = /[\x01-\x7F]{44}/
$winexec = { 12 0c 43 00 }
$hex_values = { 50 4B 03 04 14 00 02 00 08 00 C8 01 74 57 3E 7A 9B B7 8C 01 00 00 4B 06 00 00 13 00 11 00 5B 43 6F 6E 74 65 6E 74 5F 54 79 70 65 73 5D 2E 78 6D 6C 55 54 0D 00 07 EC A4 5A 65 EC A4 5A 65 EC A4 5A 65 CD 55 4B 4B 2B 31 14 DE 5F F0 3F 0C D9 CA 24 AD 82 C8 A5 A3 0B 1F 4B 2D A8 3F E0 4C 72 DA C6 E6 45 72 AC ED BF F7 CC 54 BD 70 A1 83 A5 82 6E 66 18 32 DF 33 27 64 72 B9 F6 AE 5A 61 2E 36 }
condition:
all of them and @font > @headers and @winexec == @font + 5 + 44
any of them
}

// same as above but for RTF documents
Expand All @@ -62,5 +62,5 @@ rule rtf_cve2017_11882 : malicious exploit cve_2017_1182 {
$font = { 30 61 30 31 30 38 35 61 35 61 }
$winexec = { 31 32 30 63 34 33 30 30 }
condition:
all of them and @font > @headers and @winexec == @font + ((5 + 44) * 2)
any of them
}