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efisecdb - utility for managing UEFI signature lists
Contents
Bugs
efisecdb is currently lacking several useful features:
• positional exporting of certificates
•--dump and --annotate do not adjust the output width for the terminal
• certificates can't be specified for removal by their ToBeSigned hash
January 7, 2021 EFISECDB(1)
Description
efisecdb is a command line utility for management of UEFI signature lists in detached files. That is,
it's for command line generation and management of files in the format of KEK, DB, and DBX.
Operation occurs in three phases:
1. Loading of security databases specified with --input
2. Left-to-right processing of other options, using --hash-type,--owner-guid,--add, and --remove as
state to build selectors to add or remove hashes and certificates specified by --hash and
--certificate.
3. Generation of output
The accumulated state is persistent; once an Owner GUID, Add or Delete operation, or hash type are
specified, they need only be present again to change the operations that follow. Operations are added to
the list to process when -hhash or -ccert are specified, and are processed in the order they appear.
Additionally, at least one -g argument and either --add or --remove must appear before the first use of
-hhash or -ccert.
Examples
Dumpingthecurrentsystem'sDBXdatabasewithannotations
host:~$ efisecdb-d-A-i/sys/firmware/efi/efivars/dbx-d719b2cb-3d3a-4596-a3bc-dad00e67656f
00000000 26 16 c4 c1 4c 50 92 40 ac a9 41 f9 36 93 43 28 |&...LP.@..A.6.C(| esl[0].signature_type = {sha256}
00000010 60 00 00 00 |....| esl[0].signature_list_size = 96
00000014 00 00 00 00 |....| esl[0].signature_header_size = 0
00000018 30 00 00 00 |0...| esl[0].signature_size = 48
0000001c esl[0].signature_header (end:0x0000001c)
0000001c bd 9a fa 77 |...w| esl[0].signature[0].owner = {microsoft}
00000020 59 03 32 4d bd 60 28 f4 e7 8f 78 4b |Y.2M.`(...xK|
0000002c fe cf b2 32 |...2| esl[0].signature[0].data (end:0x0000004c)
00000030 d1 2e 99 4b 6d 48 5d 2c 71 67 72 8a a5 52 59 84 |...KmH],qgr..RY.|
00000040 ad 5c a6 1e 75 16 22 1f 07 9a 14 36 |...u."....6|
0000004c bd 9a fa 77 |...w| esl[0].signature[1].owner = {microsoft}
00000050 59 03 32 4d bd 60 28 f4 e7 8f 78 4b |Y.2M.`(...xK|
0000005c fe 63 a8 4f |.c.O| esl[0].signature[1].data (end:0x0000007c)
00000060 78 2c c9 d3 fc f2 cc f9 fc 11 fb d0 37 60 87 87 |x,..........7`..|
00000070 58 d2 62 85 ed 12 66 9b dc 6e 6d 01 |X.b...f..nm.|
0000007c
BuildinganewEFISecurityDatabaseforuseasKEK,replacingonecertificate.
# Figure out the original cert... the easy way
host:~$ stringsKEK-*|grepmicrosoft.*crt
Dhttp://www.microsoft.com/pki/certs/MicCorThiParMarRoo_2010-10-05.crt0
# Find it, because --export isn't implemented yet
host:~$ wget\--user-agent='Mozilla/5.0(WindowsNT10.0;WOW64;Trident/7.0;rv:11.0)likeGecko'\http://www.microsoft.com/pki/certs/MicCorThiParMarRoo_2010-10-05.crt
--2020-06-04 20:41:27-- http://www.microsoft.com/pki/certs/MicCorThiParMarRoo_2010-10-05.crt
Resolving www.microsoft.com (www.microsoft.com)... 2600:141b:800:287::356e, 2600:141b:800:2a0::356e, 23.43.254.254
Connecting to www.microsoft.com (www.microsoft.com)|2600:141b:800:287::356e|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 1539 (1.5K) [application/octet-stream]
Saving to: ‘MicCorThiParMarRoo_2010-10-05.crt’
MicCorThiParMarRoo_ 100%[===================>] 1.50K --.-KB/s in 0s
2020-06-04 20:41:27 (177 MB/s) - ‘MicCorThiParMarRoo_2010-10-05.crt’ saved [1539/1539]
# Pick a GUID-like object, any GUID-like object...
host:~$ uuidgen
aab3960c-501e-485e-ac59-62805970a3dd
# Remove the old KEK entry and add a different one
host:~$ efisecdb-iKEK-8be4df61-93ca-11d2-aa0d-00e098032b8c\-g{microsoft}-r-cMicCorThiParMarRoo_2010-10-05.crt\-gaab3960c-501e-485e-ac59-62805970a3dd-a-cpjkek.cer\-onewkek.binSearchingthelistofwell-knownGUIDs
host:~$ efisecdb-L|grepshim
{605dab50-e046-4300-abb6-3dd810dd8b23} {shim} shim
Name
efisecdb - utility for managing UEFI signature lists
Options
⟨-s | --sort⟩ ⟨all | data | none | type⟩
Sort by data after sorting and grouping entry types, entry data, no sorting, or by entry type
⟨-s | --sort⟩ ⟨ascending | descending⟩
Sort in ascending or descending order
-ifile | --infilefile
Read EFI Security Database from file-gguid | --owner-guidguid
Use the specified GUID or symbolic refrence (i.e. {empty}) for forthcoming addition and removal
operations
-a | --add | -r | --remove
Select add or remove for forthcoming operations
-thash-type | --hash-typehash-type
Select hash-type for forthcoming addition and removal operations (default sha256)
Use hash-type help to list supported hash types.
-hhash | --hashhash
Add or remove the specified hash
-cfile | --certificatefile
Add or remove the specified certificate
-d | --dump
Produce a hex dump of the output
-A | --annotate
Annotate the hex dump produced by --dump-ofile | --outfilefile
Write EFI Security Database to file-L | --list-guids
List the well known guids
The output is tab delimited: GUID short_name desription
See Also
authvar(1), efikeygen(1), pesign(1)
Standards
UEFI Specification Working Group, UnifiedExtensibleFirmwareInterface(UEFI)SpecificationVersion2.8,
UnifiedExtensibleFirmwareInterfaceForum, https://uefi.org/specifications , March 2019.
Synopsis
efisecdb [-sSORT] [-ifile [-ifile] ...]
[-gguid ⟨-a | -r⟩ ⟨[-thash-type] -hhash | -cfile⟩
[-gguid ⟨-a | -r⟩ ⟨[-thash-type] -hhash | -cfile⟩] ...] ⟨-d [-A] | -ofile | -L⟩
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