55 Signatures

Rizin supports the HexRays FLIRT signature format, enabling users to effortlessly create, parse, or apply signatures on the go. Additionally, Rizin can automatically apply these signatures when the user defines the sigdb via the flirt.sigdb.path variable. All applied signatures are then stored within the flirt flag space.

The HexRays FLIRT format has two formats:

.pat A human-readable text string format
.sig A compressed format, which includes a name, version and the architecture type utilized for generating the signature.

Signature commands are available under the F command namespace:

[0x00000000]> F?
Usage: F<cdsfal>   # FLIRT signature management
| Fc <filename> # Create a FLIRT file (.pat or .sig)
| Fd <filename> # Open a FLIRT file (.pat or .sig) and dumps its contents
| Fs <filename> # Open a FLIRT file (.pat or .sig) and tries to apply the signatures to the loaded binary
| Ff            # Outputs the flirt function signature info
| Fa [<filter>] # Apply signatures from sigdb
| Fl[t]         # Lists all available signatures in sigdb

55.1 Signature matching

Before applying a signature, you must first analyze the binary (see code analysis chapter).

In Rizin, there are two methods to apply signatures to a file: using sigdb or manually specifying the signature file.

If e flirt.sigdb.path is configured before executing the analysis (aaa command), then sigdb files are automatically applied to the binary. However, if a manual approach is preferred, it is possible to select the FLIRT signature file from sigdb using the Fa command. To list all available signature files in sigdb, use the Fl command.

An example of selecting sigdb signatures via Fa could be:

[0x00409c70]> pdf
            ; CALL XREF from main @ 0x4017c1
/ fcn.00409c70 (int64_t arg1, int64_t arg2, int64_t arg3, int64_t arg4, int64_t arg5, int64_t arg6, int64_t arg7, int64_t arg8, int64_t arg9, int64_t arg10, int64_t arg11, int64_t arg_e0h);
|           ; var int64_t var_4h_2 @ rsp+0x4
|           ; var int64_t var_8h_2 @ rsp+0x8
|           ; var int64_t var_10h_2 @ rsp+0x10
|           ; var int64_t var_18h_2 @ rsp+0x18
|           ; var int64_t var_20h_2 @ rsp+0x20
|           ; var int64_t var_30h_2 @ rsp+0x30
|           ; var int64_t var_38h_2 @ rsp+0x38
|           ; var int64_t var_40h_2 @ rsp+0x40
[0x00409c70]> e flirt.sigdb.path=/path/to/sigdb
[0x00409c70]> Fa?
Usage: Fa [<filter>]   # Apply signatures from sigdb
[0x00409c70]> Fl?
Usage: Fl[t]   # Lists all available signatures in sigdb (table mode)
| Flt    # Lists all available signatures in sigdb (table mode)
[0x00409c70]> Flt:name/str/gcc
bin arch bits name                 modules details                                          
--------------------------------------------------------------------------------------------
elf x86  64   ubuntu-libgcc-10.sig 487     Ubuntu GCC support library Version 10 (rizin.re)
elf x86  64   ubuntu-libgcc-11.sig 298     Ubuntu GCC support library Version 11 (rizin.re)
elf x86  64   ubuntu-libgcc-12.sig 307     Ubuntu GCC support library Version 12 (rizin.re)
elf x86  64   ubuntu-libgcc-7.sig  247     Ubuntu GCC support library Version 7 (rizin.re)
elf x86  64   ubuntu-libgcc-8.sig  520     Ubuntu GCC support library Version 8 (rizin.re)
elf x86  64   ubuntu-libgcc-9.sig  535     Ubuntu GCC support library Version 9 (rizin.re)
[0x00409c70]> Fa gcc
Applying elf/x86/64/ubuntu-libgcc-10.sig signature file
Applying elf/x86/64/ubuntu-libgcc-11.sig signature file
Applying elf/x86/64/ubuntu-libgcc-12.sig signature file
Applying elf/x86/64/ubuntu-libgcc-7.sig signature file
Applying elf/x86/64/ubuntu-libgcc-8.sig signature file
Applying elf/x86/64/ubuntu-libgcc-9.sig signature file
[0x00409c70]> pdf
            ; CALL XREF from main @ 0x4017c1
            ;-- fcn.00409c70:
/ flirt.printf (int64_t arg1, int64_t arg2, int64_t arg3, int64_t arg4, int64_t arg5, int64_t arg6, int64_t arg7, int64_t arg8, int64_t arg9, int64_t arg10, int64_t arg11, int64_t arg_e0h);
|           ; var int64_t var_4h @ rsp+0xdc
|           ; var int64_t var_8h @ rsp+0xe0
|           ; var int64_t var_10h @ rsp+0xe8
|           ; var int64_t var_18h @ rsp+0xf0
|

To manually apply a signature file, you need to use the Fs command.

$ rizin /path/to/binary/with/stripped.elf
[0x00009690]> aaa
[0x00009690]> Fs signature.sig # relative or absolutes paths are accepted
Found 536 FLIRT signatures via signature.sig
[0x00009690]>

55.2 Signature creation

Before creating a signature, you must first analyze the binary (see code analysis chapter).

You can generate the signature by invoking the Fc <filename> command. You can customize the behavior of signature creation using the following options:

Signature creation options:
- flirt.ignore.unknown: When enabled, during FLIRT creation, it will disregard any function starting with fcn., default: true.
- flirt.node.optimize: FLIRT optimization option when creating a signature file (none: 0, normal: 1, smallest: 2), default: 2.
.sig (compressed format) specific options:
- flirt.sig.deflate: Enables or disables the FLIRT zlib compression when creating a signature file (available only for .sig files), default: true.
- flirt.sig.file: FLIRT file list (comma separated) for .sig format (msdos, win, os2, netware, unix, other, all, none), default: all.
- flirt.sig.library: FLIRT library name for .sig format, default: Built with rizin x.y.z.
- flirt.sig.os: FLIRT operating system list (comma separated) for .sig format (aixar, aout, ar, bin, coff, dos:com, dos:com:old, dos:exe, dos:exe:old, dosdrv, elf, intelhex, le, loader, lx, moshex, ne, nlm, omf, omflib, pe, pilot, srec, w32run, zip, all, none), default: all.
- flirt.sig.version: FLIRT version for .sig format default: 10.
sigdb specific options:
- analysis.apply.signature: Enables or disables the automatic application of signatures to the loaded binary, default: true.
- flirt.sigdb.load.extra: Load signatures from the extra path, default: true and its path can be found via rizin -H RZ_EXTRA_SIGDB.
- flirt.sigdb.load.home: Load signatures from the home path, default: true.
- flirt.sigdb.load.system: Load signatures from the system path, default: true and its path can be found via rizin -H RZ_SIGDB.
- flirt.sigdb.path: Additional user defined rizin sigdb location to load on the filesystem default: (empty).

Example of signature creation in .sig (compressed) format:

$ rizin /path/to/binary/with/symbols.elf
[0x00009690]> aa
[0x00009690]> # setting library name
[0x00009690]> e flirt.sig.library="My Awesome Library Name"
[0x00009690]> # creating signature
[0x00009690]> Fc signature.sig # relative or absolutes paths are accepted
704 FLIRT signatures were written in 'signature.sig'
[0x00009690]>

Example of signature creation in .pat (human readable) format:

$ rizin /path/to/binary/with/symbols.elf
[0x00009690]> aa
[0x00009690]> # disable internal node optimization
[0x00009690]> e flirt.node.optimize=0
[0x00009690]> # creating signature
[0x00009690]> Fc signature.pat # relative or absolutes paths are accepted
704 FLIRT signatures were written in 'signature.pat'
[0x00009690]>

You can view the contents of a FLIRT signature file via Fd <filename>.

[0x00009690]> Fd signature.sig
SIG format
Signature:    Built with rizin x.y.z, 704 modules
Version:      10
Architecture: 0 (x86)
09CA74..C30F1F00E9:
 0. 00 0000 000D 0000:sock_state_cb
0F:
 B6:
  07:
   3C..74..84C074..4C8D86FF000000EB..0F1F40003C..74..4939F074:
    0. 00 0000 0103 0000:Curl_auth_digest_get_pair
   84C0:
    0F84........0FB60E84C90F84........4885D20F84........53:
     0. 01 A5A9 0105 0000:Curl_strncasecompare
    75..E9........0F1F400041......448D50E0448D429F4189C345:
     0. 07 6545 009B 0000:Curl_strcasecompare
  4F080FB7570883....66C1C20880....74..83....41B8010000006681..:
   0. 00 0000 008A 0000:Curl_ipv6_scope.part.0
  87910B00008B9748010000F7D0C0E80781..........0F9EC108C874..31:
   0. 11 F2A8 00AF 0000:http_should_fail
 B707:
  66C1C008C3:
   0. 00 0000 0008 0000:Curl_read16_be
  C3:
   0. 00 0000 0004 0000:Curl_read16_le

You can also utilize rz-sign to automatically create, convert, or dump FLIRT signatures:

$ rz-sign -h
Usage: rz-sign [options] [file]
 -h                          Show this help
 -a [-a]                     Add extra 'a' to analysis command (available only with -o option)
 -e [k=v]                    Set an evaluable config variable (available only with -o option)
 -c [output.pat] [input.sig] Parse a FLIRT signature and convert it to its other format
 -o [output.sig] [input.bin] Perform an analysis on the binary and generate the FLIRT signature
 -d [flirt.sig]              Parse a FLIRT signature and dump its content
 -q                          Quiet mode
 -v                          Show version information
Examples:
  rz-sign -d signature.sig
  rz-sign -c new_signature.pat old_signature.sig
  rz-sign -o libc.sig libc.so.6

$ rz-sign -e "flirt.sig.library=My Awesome Library Name" -o signature.sig /path/to/binary/with/symbols.elf

For library files that use the .a or .la formats, it is highly recommended to unpack them using ar and utilize the .o files as sources for the signature files.

55.3 Signature database creation

It is possible to create personal sigdb using the sigdb tools and the scripts in sigdb source available in the RizinOrg repository.

sigdb tools
- generate-pat-from-obj.py Generates unoptimized .pat signatures from .o, .lo, or .obj object files. The tool creates a new file with the same name as the original object file but with the extension .pat.
- generate-obj-from-lib.py Unpacks Windows .lib files into .o (object files). This tool accepts a folder containing all the .lib files to unpack as input and generates multiple directories (named after the respective libraries) along with their contents (beware that this tool requires linux utilities).
- launchpad-deb-scraper.py This script downloads deb packages from launchpad leveraging high-performance asynchronous i/o. It is possible to filter the deb packages by architecture.
sigdb source
- generate-pat.py is a tool that generates a .pat file from one or multiple .pat files. It offers various options to automatically resolve conflicts. Additionally, it is possible to run it in test mode (also known as a dry run) to preview its actions without making any actual changes.
- generate-sig.py is a tool that is only used to generate .sig files for the release version of a signature database. this compress and automatically names the libraries following the sigdb source format.

Example of sigdb generation using the tools mentioned above:

# create output folders
$ mkdir mysigdb mysigdb-extract mysigdb-source

# check if there are lib files
$ find libs/ -type f -name '*.lib'
libs/libcrypto.lib
libs/libssl.lib
# unpack all lib files
$ python ~/sigdb-tools/generate-obj-from-lib.py -v --input libs/
input dir: libs/
found 2 file to ingest

[1|2] parsing libssl.lib
[2|2] parsing libcrypto.lib

done.

# create a sigdb source folder from the extracted files.
$ python ~/sigdb-tools/generate-pat-from-obj.py -i libs/ --output mysigdb-extract
input dir: libs/
found 580 file to ingest

done.
$ find mysigdb-extract/ -type f -name '*.pat' | head
mysigdb-extract/coff/x86/64/libcrypto.lib.ext/bf_ofb64.c.obj.pat
mysigdb-extract/coff/x86/64/libcrypto.lib.ext/aes_cfb.c.obj.pat
mysigdb-extract/coff/x86/64/libcrypto.lib.ext/t_req.c.obj.pat
mysigdb-extract/coff/x86/64/libcrypto.lib.ext/md5-mingw64-x86_64.S.obj.pat
mysigdb-extract/coff/x86/64/libcrypto.lib.ext/tasn_utl.c.obj.pat
mysigdb-extract/coff/x86/64/libcrypto.lib.ext/asn1_par.c.obj.pat
...

# create sigdb source folder structure.
$ mkdir -p "mysigdb-source/coff/x86/64/openssl_3_0_0"

# create sigdb library description files.
# see https://github.com/rizinorg/sigdb-source/blob/main/README.md#mandatory-folder-structure
$ echo "OpenSSL 3.0.0 for Windows" > "mysigdb-source/coff/x86/64/openssl_3_0_0/openssl_3_0_0.description"
$ sha1sum openssl.3.0.0.zip > "mysigdb-source/coff/x86/64/openssl_3_0_0/openssl_3_0_0.src.sha1"

# create sigdb source .pat from extracted files in mysigdb-extract
$ python ~/sigdb-source/.scripts/generate-pat.py --auto --recursive -d "mysigdb-extract/" -o "mysigdb-source/coff/x86/64/openssl_3_0_0/openssl_3_0_0.pat"
output: mysigdb-source/coff/x86/64/openssl_3_0_0/openssl_3_0_0.pat
input:  577 pat files
parsed a total of 6163 signatures and dropped 2082 (~34%) signatures.                   
There were 452 duplicates out of 4081 signatures (~11%).
mysigdb-source/coff/x86/64/openssl_3_0_0/openssl_3_0_0.pat has been created

# sigdb source directory is now complete.
$ find mysigdb-source/ -type f
mysigdb-source/coff/x86/64/openssl_3_0_0/openssl_3_0_0.description
mysigdb-source/coff/x86/64/openssl_3_0_0/openssl_3_0_0.pat
mysigdb-source/coff/x86/64/openssl_3_0_0/openssl_3_0_0.src.sha1

# create release compressed files in mysigdb/ using mysigdb-source/.
$ python generate-sig.py -s mysigdb-source/ -o mysigdb --test
source: mysigdb-source
output: mysigdb
Generating OpenSSL 3.0.0 for Windows signature (as openssl_3_0_0.sig) from openssl_3_0_0.pat

# Use the generated sigdb with rizin.
$ rizin -e "flirt.sigdb.path=mysigdb/" -qc 'Fl'
bin  arch bits name              modules details                              
------------------------------------------------------------------------------
coff x86  64   openssl_3_0_0.sig 3357    OpenSSL 3.0.0 for Windows (rizin.re)