Sneed-Reactivity/yara-Neo23x0/bkdr_xz_util_cve_2024_3094.yar

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rule BKDR_XZUtil_Script_CVE_2024_3094_Mar24_1 {
meta:
description = "Detects make file and script contents used by the backdoored XZ library (xzutil) CVE-2024-3094."
author = "Florian Roth"
reference = "https://www.openwall.com/lists/oss-security/2024/03/29/4"
date = "2024-03-30"
score = 80
hash = "d44d0425769fa2e0b6875e5ca25d45b251bbe98870c6b9bef34f7cea9f84c9c3"
id = "6b62ffc2-d0a7-5810-97a3-c48f7fac300e"
strings:
$x1 = "/bad-3-corrupt_lzma2.xz | tr " ascii
$x2 = "/tests/files/good-large_compressed.lzma|eval $i|tail -c +31265|" ascii
$x3 = "eval $zrKcKQ" ascii
condition:
1 of them
}
rule BKDR_XZUtil_Binary_CVE_2024_3094_Mar24_1 {
meta:
description = "Detects injected code used by the backdoored XZ library (xzutil) CVE-2024-3094."
author = "Florian Roth"
reference = "https://www.openwall.com/lists/oss-security/2024/03/29/4"
date = "2024-03-30"
score = 75
hash1 = "319feb5a9cddd81955d915b5632b4a5f8f9080281fb46e2f6d69d53f693c23ae"
hash2 = "605861f833fc181c7cdcabd5577ddb8989bea332648a8f498b4eef89b8f85ad4"
hash3 = "8fa641c454c3e0f76de73b7cc3446096b9c8b9d33d406d38b8ac76090b0344fd"
hash4 = "b418bfd34aa246b2e7b5cb5d263a640e5d080810f767370c4d2c24662a274963"
hash5 = "cbeef92e67bf41ca9c015557d81f39adaba67ca9fb3574139754999030b83537"
hash6 = "5448850cdc3a7ae41ff53b433c2adbd0ff492515012412ee63a40d2685db3049"
id = "6ccdeb6d-67c4-5358-a76b-aef7f047c997"
strings:
$op1 = { 48 8d 7c 24 08 f3 ab 48 8d 44 24 08 48 89 d1 4c 89 c7 48 89 c2 e8 ?? ?? ?? ?? 89 c2 }
$op2 = { 31 c0 49 89 ff b9 16 00 00 00 4d 89 c5 48 8d 7c 24 48 4d 89 ce f3 ab 48 8d 44 24 48 }
$op3 = { 4d 8b 6c 24 08 45 8b 3c 24 4c 8b 63 10 89 85 78 f1 ff ff 31 c0 83 bd 78 f1 ff ff 00 f3 ab 79 07 }
/* function signature from detect.sh provided by Vegard Nossum */
$xc1 = { F3 0F 1E FA 55 48 89 F5 4C 89 CE 53 89 FB 81 E7 00 00 00 80 48 83 EC 28 48 89 54 24 18 48 89 4C 24 10 }
condition:
uint16(0) == 0x457f
and (
all of ($op*)
or $xc1
)
}
rule BKDR_XZUtil_KillSwitch_CVE_2024_3094_Mar24_1 {
meta:
description = "Detects kill switch used by the backdoored XZ library (xzutil) CVE-2024-3094."
author = "Florian Roth"
reference = "https://gist.github.com/q3k/af3d93b6a1f399de28fe194add452d01?permalink_comment_id=5006558#gistcomment-5006558"
date = "2024-03-30"
score = 85
id = "0d28bec4-1d3a-5af0-9e9e-49486fcc62e1"
strings:
$x1 = "yolAbejyiejuvnup=Evjtgvsh5okmkAvj"
condition:
$x1
}
rule SUSP_OBFUSC_SH_Indicators_Mar24_1 {
meta:
description = "Detects characteristics found in obfuscated script (used in the backdoored XZ package, but could match on others, too)"
author = "Florian Roth"
reference = "https://www.openwall.com/lists/oss-security/2024/03/29/4/1"
date = "2024-04-06"
score = 60
id = "f9fcc326-75d6-5a5a-a8b5-7de15a11448e"
strings:
$s1 = "eval $"
condition:
uint8(1) == 0x3d // an equal sign at byte 2 ; means that the variable is only 1 character long
and $s1 in (filesize-20..filesize) // eval at the very end of the file
}