Sneed-Reactivity/yara-mikesxrs/Florian Roth/generic_anomalies.yar
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/*
Generic Anomalies
Florian Roth
BSK Consulting GmbH
License: Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)
Copyright and related rights waived via https://creativecommons.org/licenses/by-nc-sa/4.0/
*/
rule Embedded_EXE_Cloaking {
meta:
description = "Detects an embedded executable in a non-executable file"
author = "Florian Roth"
date = "2015/02/27"
score = 65
strings:
$noex_png = { 89 50 4E 47 }
$noex_pdf = { 25 50 44 46 }
$noex_rtf = { 7B 5C 72 74 66 31 }
$noex_jpg = { FF D8 FF E0 }
$noex_gif = { 47 49 46 38 }
$mz = { 4D 5A }
$a1 = "This program cannot be run in DOS mode"
$a2 = "This program must be run under Win32"
condition:
(
( $noex_png at 0 ) or
( $noex_pdf at 0 ) or
( $noex_rtf at 0 ) or
( $noex_jpg at 0 ) or
( $noex_gif at 0 )
)
and
for any i in (1..#mz): ( @a1 < ( @mz[i] + 200 ) or @a2 < ( @mz[i] + 200 ) )
}
rule Cloaked_as_JPG {
meta:
description = "Detects a cloaked file as JPG"
author = "Florian Roth (eval section from Didier Stevens)"
date = "2015/02/29"
score = 40
condition:
uint16be(0x00) != 0xFFD8 and
extension matches /\.jpg/i and
filetype != "GIF"
/* and
not filepath contains "ASP.NET" */
}
rule GIFCloaked_Webshell {
meta:
description = "Detects a webshell that cloakes itself with GIF header(s) - Based on Dark Security Team Webshell"
author = "Florian Roth"
hash = "f1c95b13a71ca3629a0bb79601fcacf57cdfcf768806a71b26f2448f8c1d5d24"
score = 60
strings:
$magic = "GIF"
$s0 = "input type"
$s1 = "<%eval request"
$s2 = "<%eval(Request.Item["
$s3 = "LANGUAGE='VBScript'"
condition:
( $magic at 0 ) and ( 1 of ($s*) )
}
/*
Yara Rule Set
Author: Florian Roth
Date: 2015-12-21
Identifier: Uncommon File Sizes
*/
rule Suspicious_Size_explorer_exe {
meta:
description = "Detects uncommon file size of explorer.exe"
author = "Florian Roth"
score = 60
date = "2015-12-21"
condition:
uint16(0) == 0x5a4d
and filename == "explorer.exe"
and not filepath contains "teamviewer"
and ( filesize < 1000KB or filesize > 3500KB )
}
rule Suspicious_Size_chrome_exe {
meta:
description = "Detects uncommon file size of chrome.exe"
author = "Florian Roth"
score = 60
date = "2015-12-21"
condition:
uint16(0) == 0x5a4d
and filename == "chrome.exe"
and ( filesize < 500KB or filesize > 1300KB )
}
rule Suspicious_Size_csrss_exe {
meta:
description = "Detects uncommon file size of csrss.exe"
author = "Florian Roth"
score = 60
date = "2015-12-21"
condition:
uint16(0) == 0x5a4d
and filename == "csrss.exe"
and ( filesize > 18KB )
}
rule Suspicious_Size_iexplore_exe {
meta:
description = "Detects uncommon file size of iexplore.exe"
author = "Florian Roth"
score = 60
date = "2015-12-21"
condition:
uint16(0) == 0x5a4d
and filename == "iexplore.exe"
and not filepath contains "teamviewer"
and ( filesize < 75KB or filesize > 910KB )
}
rule Suspicious_Size_firefox_exe {
meta:
description = "Detects uncommon file size of firefox.exe"
author = "Florian Roth"
score = 60
date = "2015-12-21"
condition:
uint16(0) == 0x5a4d
and filename == "firefox.exe"
and ( filesize < 265KB or filesize > 910KB )
}
rule Suspicious_Size_java_exe {
meta:
description = "Detects uncommon file size of java.exe"
author = "Florian Roth"
score = 60
date = "2015-12-21"
condition:
uint16(0) == 0x5a4d
and filename == "java.exe"
and ( filesize < 42KB or filesize > 900KB )
}
rule Suspicious_Size_lsass_exe {
meta:
description = "Detects uncommon file size of lsass.exe"
author = "Florian Roth"
score = 60
date = "2015-12-21"
condition:
uint16(0) == 0x5a4d
and filename == "lsass.exe"
and ( filesize < 10KB or filesize > 58KB )
}
rule Suspicious_Size_svchost_exe {
meta:
description = "Detects uncommon file size of svchost.exe"
author = "Florian Roth"
score = 60
date = "2015-12-21"
condition:
uint16(0) == 0x5a4d
and filename == "svchost.exe"
and ( filesize < 14KB or filesize > 40KB )
}
rule Suspicious_Size_winlogon_exe {
meta:
description = "Detects uncommon file size of winlogon.exe"
author = "Florian Roth"
score = 60
date = "2015-12-21"
condition:
uint16(0) == 0x5a4d
and filename == "winlogon.exe"
and ( filesize < 279KB or filesize > 580KB )
}
rule Suspicious_Size_igfxhk_exe {
meta:
description = "Detects uncommon file size of igfxhk.exe"
author = "Florian Roth"
score = 60
date = "2015-12-21"
condition:
uint16(0) == 0x5a4d
and filename == "igfxhk.exe"
and ( filesize < 200KB or filesize > 265KB )
}
rule Suspicious_Size_servicehost_dll {
meta:
description = "Detects uncommon file size of servicehost.dll"
author = "Florian Roth"
score = 60
date = "2015-12-23"
condition:
uint16(0) == 0x5a4d
and filename == "servicehost.dll"
and filesize > 150KB
}
rule Suspicious_Size_rundll32_exe {
meta:
description = "Detects uncommon file size of rundll32.exe"
author = "Florian Roth"
score = 60
date = "2015-12-23"
condition:
uint16(0) == 0x5a4d
and filename == "rundll32.exe"
and ( filesize < 30KB or filesize > 60KB )
}
rule Suspicious_Size_taskhost_exe {
meta:
description = "Detects uncommon file size of taskhost.exe"
author = "Florian Roth"
score = 60
date = "2015-12-23"
condition:
uint16(0) == 0x5a4d
and filename == "taskhost.exe"
and ( filesize < 45KB or filesize > 85KB )
}
rule Suspicious_Size_spoolsv_exe {
meta:
description = "Detects uncommon file size of spoolsv.exe"
author = "Florian Roth"
score = 60
date = "2015-12-23"
condition:
uint16(0) == 0x5a4d
and filename == "spoolsv.exe"
and ( filesize < 50KB or filesize > 930KB )
}
rule Suspicious_Size_smss_exe {
meta:
description = "Detects uncommon file size of smss.exe"
author = "Florian Roth"
score = 60
date = "2015-12-23"
condition:
uint16(0) == 0x5a4d
and filename == "smss.exe"
and ( filesize < 40KB or filesize > 320KB )
}
rule Suspicious_Size_wininit_exe {
meta:
description = "Detects uncommon file size of wininit.exe"
author = "Florian Roth"
score = 60
date = "2015-12-23"
condition:
uint16(0) == 0x5a4d
and filename == "wininit.exe"
and ( filesize < 90KB or filesize > 300KB )
}