Awesome

asafw

Preliminary note: we recommend you to use this as part of asatools but it can also be used standalone.

asafw is a set of scripts to deal with Cisco ASA firmware. It allows someone to unpack firmware required when debugging with gdb, as well as unpacking/repacking them in order to enable certain features such as:

• Enabling gdb at boot
• Disabling ASLR to ease debugging
• Injecting a Linux debug shell to allow CTRL^C in gdb when used with real hardware
• Rooting a firmware (generally deprecated by enabling gdb at boot and injecting a root shell)
• etc.

The more useful tools are unpack_repack_bin.sh and unpack_repack_qcow2.sh. They allow respectively to manipulate asa*.bin and asav*.qcow2 image formats. They both need to be executed as root when actually repacking rootfs to keep the right permissions.

Requirements

• Python3 only
• apt install binwalk qemu-utils
• Heavily tested on Linux (but could work on OS X to)

You initially need to modify asafw/env.sh to match your environment. It will allow you to define paths to the tools used by all the scripts as well as some variables matching your ASA environment. Note there is a simmilar asadbg/env.sh but only one is required to be used for both projects. We recommend that you add it to your ~/.bashrc:

source /path/to/asafw/env.sh

unpack_repack_bin.sh

unpack_repack_bin.sh is used to unpack/repack asa*.bin images which are used for real Cisco ASA hardware (such as ASA 5500 and 5500-X series). The complete usage is:

$ unpack_repack_bin.sh -h
Usage:
./unpack_repack_bin.sh -i <firmware_file> -o <out_dir> [-f -g -G -a -A -m -b -r -u -l <linabin_dir> -d -e -k]
      -h, --help                    This help menu
      -i, --input <firmware_file>   What firmware bin to operate on
      -o, --output  <out_dir>       Where to write new firmware
      -f, --free-space              Remove space from .bin to ensure injections fit
      -g, --enable-gdb              Set gdb to start on boot
      -G, --disable-gdb             Stop gdb from starting on boot
      -a, --enable-aslr             Turn on ASLR
      -A, --disable-aslr            Turn off ASLR
      -m, --inject-gdb              Inject gdbserver to run
      -b, --debug-shell             Inject ssh-triggered debug shell
      -H, --lina-hook               Inject hooks for monitor lina heap (requires -b)
      -r, --root                    root the bin to get a rootshell on boot
      -c, --custom                  custom?
      -n, --n-custom                custom?
      -q, --gns3-fixup              gns?
      -u, --unpack-only             unpack the firmware and nothing else
      -l, --linabins <linabin_dir>  destination folder to save lina binaries
      -d, --delete-extracted        delete files extracted during modification
      -e, --delete-original-bin     delete the original firmware being modified
      -k, --keep-rootfs             keep the extracted rootfs on disk
      -s, --simple-name             use a simple name for the output .bin with just appended '-repacked'
Examples:
 ./unpack_repack_bin.sh -i /home/user/firmware -o /home/user/firmware_repacked --free-space --enable-gdb --inject-gdb
 ./unpack_repack_bin.sh -i /home/user/firmware/asa961-smp-k8.bin -f -g -m
 ./unpack_repack_bin.sh -u -i /home/user/firmware -l /home/user/linabins
 ./unpack_repack_bin.sh -u -i /home/user/firmware/asa924-k8.bin -k

Extract multiple firmare

Let's assume we have these two firmware:

~/fw$ ls
asa924-k8.bin  asa981-smp-k8.bin

If you only want to extract firmware, e.g. to debug them with asadbg, you can use -u to unpack only and -k to only keep the rootfs and delete other files extracted by binwalk that you don't need. Note that the output folder is the same as the input folder as we rely on binwalk for this:

~/fw$ unpack_repack_bin.sh -i . -k -u
[unpack_repack_bin] Directory of firmware detected: .
[unpack_repack_bin] extract_one: asa924-k8.bin

DECIMAL       HEXADECIMAL     DESCRIPTION
--------------------------------------------------------------------------------
75000         0x124F8         SHA256 hash constants, little endian
144510        0x2347E         gzip compressed data, maximum compression, from Unix, last modified: 2015-07-15 04:53:23
1501296       0x16E870        gzip compressed data, has original file name: "rootfs.img", from Unix, last modified: 2015-07-15 05:19:52
27168620      0x19E8F6C       MySQL ISAM index file Version 4
28192154      0x1AE2D9A       Zip archive data, at least v2.0 to extract, name: com/cisco/webvpn/csvrjavaloader64.dll
28773362      0x1B70BF2       Zip archive data, at least v2.0 to extract, name: AliasHandlerWrapper-win64.dll

[unpack_repack_bin] Extracted firmware to /home/user/fw/_asa924-k8.bin.extracted
[unpack_repack_bin] Firmware uses regular rootfs/ dir
[unpack_repack_bin] Extracting /home/user/fw/_asa924-k8.bin.extracted/rootfs/rootfs.img into /home/user/fw/_asa924-k8.bin.extracted/rootfs
[unpack_repack_bin] Keeping rootfs
[unpack_repack_bin] Deleting "/home/user/fw/_asa924-k8.bin.extracted/rootfs.img"
[unpack_repack_bin] Deleting "/home/user/fw/_asa924-k8.bin.extracted/2347E"
[unpack_repack_bin] Deleting "/home/user/fw/_asa924-k8.bin.extracted/1AE2D9A.zip"
[unpack_repack_bin] extract_one: asa981-smp-k8.bin

DECIMAL       HEXADECIMAL     DESCRIPTION
--------------------------------------------------------------------------------
75264         0x12600         SHA256 hash constants, little endian
133120        0x20800         Microsoft executable, portable (PE)
149183        0x246BF         gzip compressed data, maximum compression, from Unix, last modified: 2017-01-30 19:33:09
3678112       0x381FA0        gzip compressed data, has original file name: "rootfs.img", from Unix, last modified: 2017-05-10 22:42:05
14838307      0xE26A23        MySQL MISAM compressed data file Version 4
87985870      0x53E8ECE       MySQL MISAM compressed data file Version 7
96261881      0x5BCD6F9       Zip archive data, at least v2.0 to extract, name: com/cisco/webvpn/csvrjavaloader64.dll
96890193      0x5C66D51       MySQL ISAM compressed data file Version 5

[unpack_repack_bin] Extracted firmware to /home/user/fw/_asa981-smp-k8.bin.extracted
[unpack_repack_bin] Firmware uses regular rootfs/ dir
[unpack_repack_bin] Extracting /home/user/fw/_asa981-smp-k8.bin.extracted/rootfs/rootfs.img into /home/user/fw/_asa981-smp-k8.bin.extracted/rootfs
[unpack_repack_bin] Keeping rootfs
[unpack_repack_bin] Deleting "/home/user/fw/_asa981-smp-k8.bin.extracted/rootfs.img"
[unpack_repack_bin] Deleting "/home/user/fw/_asa981-smp-k8.bin.extracted/5BCD6F9.zip"
[unpack_repack_bin] Deleting "/home/user/fw/_asa981-smp-k8.bin.extracted/246BF"

Note that errors like below you may get don't matter in this case because you are not going to repack the firmware:

cpio: lib/udev/devices/kmem: Function mknod failed: Operation not permitted
cpio: lib/udev/devices/net/tun: Function mknod failed: Operation not permitted
cpio: lib/udev/devices/loop01: Function mknod failed: Operation not permitted
cpio: lib/udev/devices/null: Function mknod failed: Operation not permitted
cpio: lib/udev/devices/console: Function mknod failed: Operation not permitted
cpio: lib/udev/devices/loop00: Function mknod failed: Operation not permitted
134992 blocks

Enable gdb at boot / debug shell

Let's assume we have these two firmware:

~/fw$ ls
asa924-k8.bin  asa981-smp-k8.bin

We enable gdb with -g and remove some unused files with -f to be able to repack the firmware (the compressed rootfs needs to be smaller than the original one). We also patch lina to add a debug shell with -b. As we see below, it worked for asa924-k8.bin but it failed for asa981-smp-k8.bin. This is because we haven't added the target to our json database:

~/fw# unpack_repack_bin.sh -i . -f -g -b -o .
[unpack_repack_bin] Directory of firmware detected: .
[unpack_repack_bin] unpack_one: asa924-k8.bin
[bin] Unpacking...
[bin] Writing /home/user/fw/asa924-k8-initrd-original.gz (29013841 bytes)...
[bin] unpack: Writing /home/user/fw/asa924-k8-vmlinuz (1368176 bytes)...
134992 blocks
[unpack_repack_bin] modify_one: asa924-k8.bin
[unpack_repack_bin] ENABLE GDB
[unpack_repack_bin] FREE SPACE IN .BIN
[unpack_repack_bin] Using 32-bit firmware
[unpack_repack_bin] Adding debug shell for 192.168.210.78:4444
[lina] WARN: No index specified. Will guess based on lina path...
[lina] Using index: 132 for asa924-k8.bin
[lina] Input file: /home/user/fw/work/asa/bin/lina
[lina] Size of clean lina: 43386588 bytes
[lina] Patching lina offset: 0x3db00 with len = 445 bytes
[lina] Output file: /home/user/fw/work/asa/bin/lina
[unpack_repack_bin] repack_one: asa924-k8.bin
132192 blocks
[bin] Repacking...
[bin] repack: Writing ./asa924-k8-debugshell-gdbserver.bin (30597120 bytes)...
[unpack_repack_bin] MD5: 6ee6af342a5b1ef31d633fca6dfa0d1a  ./asa924-k8-debugshell-gdbserver.bin
[unpack_repack_bin] CLEANUP
[unpack_repack_bin] unpack_one: asa981-smp-k8.bin
[bin] Unpacking...
[bin] Writing /home/user/fw/asa981-smp-k8-initrd-original.gz (100973358 bytes)...
[bin] Could not find Direct booting from string
[bin] Probably handling a 64-bit firmware...
[bin] unpack: Writing /home/user/fw/asa981-smp-k8-vmlinuz (3544992 bytes)...
458699 blocks
[unpack_repack_bin] modify_one: asa981-smp-k8.bin
[unpack_repack_bin] ENABLE GDB
[unpack_repack_bin] FREE SPACE IN .BIN
[unpack_repack_bin] Using 32-bit firmware
[unpack_repack_bin] Adding debug shell for 192.168.210.78:4444
[lina] WARN: No index specified. Will guess based on lina path...
[lina] [x] Failed to get target index matching bin name
/path/asafw/lina.py -b asa981-smp-k8.bin -f /home/user/fw/work/asa/bin/lina -o /home/user/fw/work/asa/bin/lina -c 192.168.210.78 -p 4444 -d /path/to/asadbg/asadb.json failed

As you can see we get an additional firmware with gdb enabled: asa924-k8-debugshell-gdbserver.bin that can be used with asadbg.

~/fw# ls
asa924-k8.bin                       asa981-smp-k8.bin                   asa981-smp-k8-initrd-original.gz  work
asa924-k8-debugshell-gdbserver.bin  asa981-smp-k8-initrd-original.cpio  asa981-smp-k8-vmlinuz

Also the latest extracted rootfs is kept in work for debugging purpose. The remaining files for asa981-smp-* are there because of the failure. You can use the idahunt scripts in asadbg to import the new lina. You can more specifically refer to the Importing additional symbols section in the README.

Retrieve lina and co files for future analysis

Because firmware files are quite big, and extracted files are even worse, it may be interesting to extract each firmware, get the lina, lina_monitor files and then delete temporary extracted files.

You can do it with the following command line:

$ unpack_repack_bin.sh -u -i /home/user/fw/ --linabins /home/user/linabins/ --delete-extracted
[unpack_repack_bin] Created /home/user/linabins/ directory
[unpack_repack_bin] Directory of firmware detected: /home/user/fw/
[unpack_repack_bin] extract_bin: asa924-25-k8.bin
[unpack_repack_bin] Extracted firmware to /home/user/fw/_asa924-25-k8.bin.extracted
[unpack_repack_bin] Firmware uses regular rootfs/ dir
[unpack_repack_bin] Extracting /home/user/fw/_asa924-25-k8.bin.extracted/rootfs/rootfs.img into /home/user/fw/_asa924-25-k8.bin.extracted/rootfs
[unpack_repack_bin] Deleting extracted files
[unpack_repack_bin] Deleting "/home/user/fw/_asa924-25-k8.bin.extracted"
[unpack_repack_bin] extract_bin: asa924-27-k8.bin
[unpack_repack_bin] Extracted firmware to /home/user/fw/_asa924-27-k8.bin.extracted
[unpack_repack_bin] Firmware uses regular rootfs/ dir
[unpack_repack_bin] Extracting /home/user/fw/_asa924-27-k8.bin.extracted/rootfs/rootfs.img into /home/user/fw/_asa924-27-k8.bin.extracted/rootfs
[unpack_repack_bin] Deleting extracted files
[unpack_repack_bin] Deleting "/home/user/fw/_asa924-27-k8.bin.extracted"
[unpack_repack_bin] extract_bin: asa924-k8.bin
[unpack_repack_bin] Extracted firmware to /home/user/fw/_asa924-k8.bin.extracted
[unpack_repack_bin] Firmware uses regular rootfs/ dir
[unpack_repack_bin] Extracting /home/user/fw/_asa924-k8.bin.extracted/rootfs/rootfs.img into /home/user/fw/_asa924-k8.bin.extracted/rootfs
[unpack_repack_bin] Deleting extracted files
[unpack_repack_bin] Deleting "/home/user/fw/_asa924-k8.bin.extracted"
$ tree /home/user/linabins/
/home/user/linabins/
├── asa924-25-k8.bin
│   ├── lina
│   └── lina_monitor
├── asa924-27-k8.bin
│   ├── lina
│   └── lina_monitor
└── asa924-k8.bin
    ├── lina
    └── lina_monitor

3 directories, 6 files

unpack_repack_qcow2.sh

Extract one firmware

You need to be root even if you just want to unpack firmware:

$ unpack_repack_qcow2.sh -i asav941-200.qcow2 -u
[unpack_repack_qcow2] You need to be root to mount/unmount the qcow2

You can extract one asav*.qcow2 image with the following. Again -u is used to unpack only.

~/fw_qcow2# unpack_repack_qcow2.sh -i asav941-200.qcow2 -u
[unpack_repack_qcow2] Using input qcow2 file: asav941-200.qcow2
[unpack_repack_qcow2] Using template qcow2 file: asav941-200.qcow2
[unpack_repack_qcow2] Using output qcow2 file: /home/user/fw_qcow2/asav941-200-repacked.qcow2
[unpack_repack_qcow2] Command line: -f 
[unpack_repack_qcow2] extract_one: asav941-200.qcow2
[unpack_repack_qcow2] Mounted /dev/nbd01 to /home/user/mnt/qcow2
[unpack_repack_qcow2] Copied asa941-200-smp-k8.bin to /home/user/fw_qcow2/bin/asav941-200.qcow2
[unpack_repack_qcow2] Unmounted /home/user/mnt/qcow2
[unpack_repack_bin] Single firmware detected
[unpack_repack_bin] extract_one: asav941-200.qcow2

DECIMAL       HEXADECIMAL     DESCRIPTION
--------------------------------------------------------------------------------
74656         0x123A0         SHA256 hash constants, little endian
133120        0x20800         Microsoft executable, portable (PE)
149183        0x246BF         gzip compressed data, maximum compression, from Unix, last modified: 1970-01-01 00:00:00 (null date)
3447872       0x349C40        gzip compressed data, has original file name: "rootfs.img", from Unix, last modified: 2015-05-12 00:16:47
68057161      0x40E7849       Zip archive data, at least v2.0 to extract, name: com/cisco/webvpn/csvrjavaloader64.dll
68700208      0x4184830       Zip archive data, at least v2.0 to extract, name: libAliasHandlerWrapper-mac.jnilib

[unpack_repack_bin] Extracted firmware to /home/user/fw_qcow2/bin/_asav941-200.qcow2.extracted
[unpack_repack_bin] Firmware uses regular rootfs/ dir
[unpack_repack_bin] Extracting /home/user/fw_qcow2/bin/_asav941-200.qcow2.extracted/rootfs/rootfs.img into /home/user/fw_qcow2/bin/_asav941-200.qcow2.extracted/rootfs
334503 blocks
[unpack_repack_bin] Keeping rootfs
[unpack_repack_bin] Deleting "/home/user/fw_qcow2/bin/_asav941-200.qcow2.extracted/rootfs.img"
[unpack_repack_bin] Deleting "/home/user/fw_qcow2/bin/_asav941-200.qcow2.extracted/246BF"
[unpack_repack_bin] Deleting "/home/user/fw_qcow2/bin/_asav941-200.qcow2.extracted/40E7849.zip"

We can access the extracted rootfs or use it with asadbg.

~/fw_qcow2# ls
asav941-200.qcow2  _asav941-200.qcow2.extracted  asav971.qcow2  bin
~/fw_qcow2# ls _asav941-200.qcow2.extracted/rootfs/
asa  bin  boot  dev  etc  home  init  lib  lib64  media  mnt  proc  root  run  sbin  sys  tmp  usr  var

Enable gdb at boot / disable ASLR

You can enable gdb at boot with -g and disable ASLR with -A. This allows debugging the firmware with gdb after loading it with GNS3:

~/fw_qcow2# unpack_repack_qcow2.sh -i asav962-7.qcow2 -g -A 
[unpack_repack_qcow2] Using input qcow2 file: asav962-7.qcow2
[unpack_repack_qcow2] Using template qcow2 file: asav962-7.qcow2
[unpack_repack_qcow2] Using output qcow2 file: /home/user/fw_qcow2/asav962-7-repacked.qcow2
[unpack_repack_qcow2] Command line: -f  -g -A
[unpack_repack_qcow2] extract_repack_one: asav962-7.qcow2
[unpack_repack_qcow2] Mounted /dev/nbd01 to /home/user/mnt/qcow2
[unpack_repack_qcow2] Copied asa962-7-smp-k8.bin to /home/user/fw_qcow2/bin/asav962-7.qcow2
[unpack_repack_qcow2] Unmounted /home/user/mnt/qcow2
[unpack_repack_bin] Single firmware detected
[unpack_repack_bin] unpack_one: asav962-7.qcow2
[bin] Unpacking...
[bin] Writing /home/user/fw_qcow2/bin/asav962-7-initrd-original.gz (86019506 bytes)...
[bin] Could not find Direct booting from string
[bin] Probably handling a 64-bit firmware...
[bin] unpack: Writing /home/user/fw_qcow2/bin/asav962-7-vmlinuz (3624768 bytes)...
455629 blocks
[unpack_repack_bin] modify_one: asav962-7.qcow2
[unpack_repack_bin] DISABLE ASLR
[unpack_repack_bin] ENABLE GDB
[unpack_repack_bin] FREE SPACE IN .BIN
[unpack_repack_bin] repack_one: asav962-7.qcow2
442851 blocks
[bin] Repacking...
[bin] repack: Writing /home/user/fw_qcow2/bin/asav962-7-repacked-gdbserver.qcow2 (89874432 bytes)...
[unpack_repack_bin] MD5: b898d5db383a95fa412527f8b1cd52e4  /home/user/fw_qcow2/bin/asav962-7-repacked-gdbserver.qcow2
[unpack_repack_bin] CLEANUP
[unpack_repack_qcow2] Mounted /dev/nbd01 to /home/user/mnt/qcow2
[unpack_repack_qcow2] Moved modified .bin inside of /home/user/fw_qcow2/asav962-7-repacked.qcow2
[unpack_repack_qcow2] Unmounted /home/user/mnt/qcow2

The obtained /home/user/fw_qcow2/asav962-7-repacked.qcow2 has both gdb enabled at boot and ASLR disabled.

Retrieve lina and co files for future analysis

Similarly to the asa*.bin files, but with a different command line and as root:

# for QCOW2FILE in $(find /home/user/fw/*); do echo --- Handling $QCOW2FILE; unpack_repack_qcow2.sh -u -i $QCOW2FILE; done
--- Handling /home/user/fw/asav962-2.qcow2
[unpack_repack_qcow2] Using input qcow2 file: /home/user/fw/asav962-2.qcow2
[unpack_repack_qcow2] Using template qcow2 file: /home/user/fw/asav962-2.qcow2
[unpack_repack_qcow2] Using output qcow2 file: /home/user/fw/asav962-2-repacked.qcow2
[unpack_repack_qcow2] Command line: -f 
[unpack_repack_qcow2] extract_one: /home/user/fw/asav962-2.qcow2
[unpack_repack_qcow2] Mounting /home/user/fw/asav962-2.qcow2 to /dev/nbd0
[unpack_repack_qcow2] Mounted /dev/nbd0p1 to /home/user/mnt/qcow2
[unpack_repack_qcow2] Copied asa962-2-smp-k8.bin to /home/user/fw/bin/asav962-2.qcow2
[unpack_repack_qcow2] Unmounted /home/user/mnt/qcow2
[unpack_repack_qcow2] Disconnecting /dev/nbd0
[unpack_repack_bin] Single firmware detected
[unpack_repack_bin] extract_bin: asav962-2.qcow2
[unpack_repack_bin] Extracted firmware to /home/user/fw/bin/_asav962-2.qcow2.extracted
[unpack_repack_bin] Firmware uses regular rootfs/ dir
[unpack_repack_bin] Extracting /home/user/fw/bin/_asav962-2.qcow2.extracted/rootfs/rootfs.img into /home/user/fw/bin/_asav962-2.qcow2.extracted/rootfs
--- Handling /home/user/fw/asav962-7.qcow2
[unpack_repack_qcow2] Using input qcow2 file: /home/user/fw/asav962-7.qcow2
[unpack_repack_qcow2] Using template qcow2 file: /home/user/fw/asav962-7.qcow2
[unpack_repack_qcow2] Using output qcow2 file: /home/user/fw/asav962-7-repacked.qcow2
[unpack_repack_qcow2] Command line: -f 
[unpack_repack_qcow2] extract_one: /home/user/fw/asav962-7.qcow2
[unpack_repack_qcow2] Mounting /home/user/fw/asav962-7.qcow2 to /dev/nbd0
[unpack_repack_qcow2] Mounted /dev/nbd0p1 to /home/user/mnt/qcow2
[unpack_repack_qcow2] Copied asa962-7-smp-k8.bin to /home/user/fw/bin/asav962-7.qcow2
[unpack_repack_qcow2] Unmounted /home/user/mnt/qcow2
[unpack_repack_qcow2] Disconnecting /dev/nbd0
[unpack_repack_bin] Single firmware detected
[unpack_repack_bin] extract_bin: asav962-7.qcow2
[unpack_repack_bin] Extracted firmware to /home/user/fw/bin/_asav962-7.qcow2.extracted
[unpack_repack_bin] Firmware uses regular rootfs/ dir
[unpack_repack_bin] Extracting /home/user/fw/bin/_asav962-7.qcow2.extracted/rootfs/rootfs.img into /home/user/fw/bin/_asav962-7.qcow2.extracted/rootfs
--- Handling /home/user/fw/asav962.qcow2
[unpack_repack_qcow2] Using input qcow2 file: /home/user/fw/asav962.qcow2
[unpack_repack_qcow2] Using template qcow2 file: /home/user/fw/asav962.qcow2
[unpack_repack_qcow2] Using output qcow2 file: /home/user/fw/asav962-repacked.qcow2
[unpack_repack_qcow2] Command line: -f 
[unpack_repack_qcow2] extract_one: /home/user/fw/asav962.qcow2
[unpack_repack_qcow2] Mounting /home/user/fw/asav962.qcow2 to /dev/nbd0
[unpack_repack_qcow2] Mounted /dev/nbd0p1 to /home/user/mnt/qcow2
[unpack_repack_qcow2] Copied asa962-smp-k8.bin to /home/user/fw/bin/asav962.qcow2
[unpack_repack_qcow2] Unmounted /home/user/mnt/qcow2
[unpack_repack_qcow2] Disconnecting /dev/nbd0
[unpack_repack_bin] Single firmware detected
[unpack_repack_bin] extract_bin: asav962.qcow2
[unpack_repack_bin] Extracted firmware to /home/user/fw/bin/_asav962.qcow2.extracted
[unpack_repack_bin] Firmware uses regular rootfs/ dir
[unpack_repack_bin] Extracting /home/user/fw/bin/_asav962.qcow2.extracted/rootfs/rootfs.img into /home/user/fw/bin/_asav962.qcow2.extracted/rootfs
# cd /home/user/fw/
# linabins.sh /home/user/linabins
_asav962-2.qcow2.extracted/rootfs/asa/bin/lina
_asav962-2.qcow2.extracted/rootfs/asa/bin/lina_monitor
_asav962-7.qcow2.extracted/rootfs/asa/bin/lina
_asav962-7.qcow2.extracted/rootfs/asa/bin/lina_monitor
_asav962.qcow2.extracted/rootfs/asa/bin/lina
_asav962.qcow2.extracted/rootfs/asa/bin/lina_monitor
# tree /home/user/linabins
/home/user/linabins
├── asav962-2.qcow2
│   ├── lina
│   └── lina_monitor
├── asav962-7.qcow2
│   ├── lina
│   └── lina_monitor
└── asav962.qcow2
    ├── lina
    └── lina_monitor

3 directories, 6 files

Firmware helpers

bin.py

bin.py is used to manipulate asa*.bin images. It is mainly used by unpack_repack_bin.sh and unpack_repack_qcow2.sh.

$ bin.py -h
usage: bin.py [-h] [-f FIRMWARE_FILE] [-g GZIP_FILE] [-u] [-r] [-t] [-T]
              [-o OUTPUTFILE]

optional arguments:
  -h, --help            show this help message and exit
  -f FIRMWARE_FILE, --firmware-file FIRMWARE_FILE
  -g GZIP_FILE, --gzip-file GZIP_FILE
  -u, --unpack
  -r, --repack
  -t, --root
  -T, --unroot
  -o OUTPUTFILE, --output-file OUTPUTFILE

It can still be used to quickly extract a Linux kernel and a rootfs from an asa*.bin firmware:

$ bin.py -f asa924-k8.bin -u
[bin] Unpacking...
[bin] Writing asa924-k8-initrd-original.gz (29013841 bytes)...
[bin] unpack: Writing asa924-k8-vmlinuz (1368176 bytes)...
$ file asa924-k8-*
asa924-k8-initrd-original.gz:       gzip compressed data, was "rootfs.img", from Unix, last modified: Wed Jul 15 06:19:52 2015
asa924-k8-vmlinuz:                  x86 boot sector

You can also use it to root a single binary:

$ bin.py -f asa924-k8.bin -t
[bin] root: Writing asa924-k8-rooted.bin (30597120 bytes)...

We check the differences in the two asa*.bin:

$ xxd asa924-k8.bin > b1.hex
$ xxd asa924-k8-rooted.bin > b2.hex
$ diff b1.hex b2.hex 
1907204,1907206c1907204,1907206
< 1d1a030: 0048 2000 70e0 1400 51b7 ba01 7175 6965  .H .p...Q...quie
< 1d1a040: 7420 6c6f 676c 6576 656c 3d30 2061 7574  t loglevel=0 aut
< 1d1a050: 6f20 6b73 7461 636b 3d31 3238 2072 6562  o kstack=128 reb
---
> 1d1a030: 0048 2000 70e0 1400 51b7 ba01 7264 696e  .H .p...Q...rdin
> 1d1a040: 6974 3d2f 6269 6e2f 7368 2020 2020 2020  it=/bin/sh      
> 1d1a050: 2020 6b73 7461 636b 3d31 3238 2072 6562    kstack=128 reb

cpio.sh

The cpio.sh is used to manipulate CPIO images (rootfs). It is mainly used by unpack_repack_bin.sh and unpack_repack_qcow2.sh. It's a pretty slim wrapper around cpio to just combine a few commands together for convenience:

$ cpio.sh -h
Unknown option
-c  Create cpio image
-d  Directory to turn into cpio image
-e  Extract cpio image
-o  Output file
Examples:
Create ./cpio.sh -c -d rootfs -o rootfs.img
Extract ./cpio.sh -e -i rootfs.img

If you want to play with it as standalone, you can do the following. After extracting a gzipped rootfs with bin.py, we decompress it:

$ gunzip asa924-k8-initrd-original.gz
$ file asa924-k8-initrd-original 
asa924-k8-initrd-original: ASCII cpio archive (SVR4 with no CRC)

Now we extract the rootfs into the rootfs_924 folder:

$ cpio.sh -e -i asa924-k8-initrd-original -d rootfs_924
$ ls rootfs_924/
asa  bin  boot  config  dev  etc  home  init  lib  lib64  linuxrc  mnt  opt  proc  root  sbin  share  sys  tmp  usr  var

lina.py

lina.py is used to patch the main Cisco ASA executable a.k.a. lina. It is mainly used by unpack_repack_bin.sh and unpack_repack_qcow2.sh.

$ lina.py -h
usage: lina.py [-h] [-c CBHOST] [-p CBPORT] [--log-port CBLOGPORT]
               [-i TARGET_INDEX] [-f LINA_FILE] [-b BIN_NAME]
               [-o LINA_FILE_OUT] [--hook] [-v] [-d TARGET_FILE]

optional arguments:
  -h, --help            show this help message and exit
  -c CBHOST             Attacker or debugger IP addr for reverse shell
  -p CBPORT             Attacker or debugger port for reverse shell
  --log-port CBLOGPORT  Port for sending hook logs
  -i TARGET_INDEX       Index of the target (use -l to list them all)
  -f LINA_FILE          Input lina file
  -b BIN_NAME           Input bin name
  -o LINA_FILE_OUT      Output lina file
  --hook                Insert lina hooks
  -v                    Display more info
  -d TARGET_FILE        JSON db name

We can use it as a standalone tool to patch lina to contain a debug shell. We use the asadbg.json from asadbg as it already contains addresses required. Otherwise you may need to use idahunt to find them first.

$ lina.py -c 192.168.1.1 -p 5555 -f _asa924-k8.bin.extracted/rootfs/asa/bin/lina -b asa924-k8.bin -o lina_patched -d /path/to/asadbg/asadb.json 
[lina] WARN: No index specified. Will guess based on lina path...
[lina] Using index: 0 for asa924-k8.bin
[lina] Input file: _asa924-k8.bin.extracted/rootfs/asa/bin/lina
[lina] Size of clean lina: 43386588 bytes
[lina] Patching lina offset: 0x3db00 with len = 445 bytes
[lina] Output file: lina_patched

We can check that it just patched one function with the reverse debug shell shellcode:

$ xxd _asa924-k8.bin.extracted/rootfs/asa/bin/lina > b1.hex
$ xxd lina_patched > b2.hex
$ diff b1.hex b2.hex 
15793,15820c15793,15820
< 003db00: 5589 e557 5653 81ec 8c05 0000 8b7d 208d  U..WVS.......} .
< 003db10: 45f0 c745 f001 0000 0066 c745 b0c1 1085  E..E.....f.E....
< 003db20: ffc7 45b4 0400 0000 8945 b866 c745 bc00  ..E......E.f.E..
< 003db30: 00c7 45c0 0000 0000 c745 c400 0000 0074  ..E......E.....t
< 003db40: 088b 4520 66c7 0000 008b 7524 85f6 7409  ..E f.....u$..t.
< 003db50: 8b55 24c7 0200 0000 008d 95f4 feff ff31  .U$............1
< 003db60: db89 d789 d8b9 2000 0000 f3ab c785 f4fe  ...... .........
< 003db70: ffff 0100 0000 c785 50ff ffff ffff ffff  ........P.......
< 003db80: 8b45 0889 1424 8985 68ff ffff e8bf 3525  .E...$..h.....5%
< 003db90: 01c7 85a4 faff ff00 0000 0085 c089 85a0  ................
< 003dba0: faff ff0f 849f 0400 008b 4018 8db5 38fe  ..........@...8.
< 003dbb0: ffff 89f7 8904 24e8 24a9 2501 b92f 0000  ......$.$.%../..
< 003dbc0: 0089 85b0 faff ff89 d8f3 abc7 8538 feff  .............8..
< 003dbd0: ff00 0000 008b 95a0 faff ff8b 7d08 8b42  ............}..B
< 003dbe0: 1889 853c feff ff8b 4244 897c 2404 c785  ...<....BD.|$...
< 003dbf0: 4cfe ffff ffff ffff c785 48fe ffff ffff  L.........H.....
< 003dc00: ffff 8985 44fe ffff 8934 24e8 e0f8 ffff  ....D....4$.....
< 003dc10: b909 0000 0089 8590 faff ff8d 8574 ffff  .............t..
< 003dc20: ff89 859c faff ff89 c789 d8f3 abc7 85a4  ................
< 003dc30: faff ffff ffff ff83 bd90 faff ffff 0f84  ................
< 003dc40: 1c04 0000 8d85 b4fa ffff b1a1 8985 98fa  ................
< 003dc50: ffff 89c7 89d8 f3ab 8d95 b4fa ffff 8d9d  ................
< 003dc60: 33fb ffff 8b4d 0ceb 138d b426 0000 0000  3....M.....&....
< 003dc70: 8802 83c2 0139 da74 0a83 c101 0fb6 0184  .....9.t........
< 003dc80: c075 edc6 0200 8d9d b3fb ffff 8b4d 108d  .u...........M..
< 003dc90: 9534 fbff ffeb 0d90 8802 83c2 0139 da74  .4...........9.t
< 003dca0: 0a83 c101 0fb6 0184 c075 edc6 0200 8b55  .........u.....U
< 003dcb0: 148d bd6c 2e00 008b 4508 c785 10fd ffff  ...l....E.......
---
> 003db00: b840 bc2a 09ff d0b8 0200 0000 cd80 85c0  .@.*............
> 003db10: 0f85 a101 0000 baed 0100 00b9 c200 0000  ................
> 003db20: 682f 7368 0068 2f74 6d70 8d1c 24b8 0500  h/sh.h/tmp..$...
> 003db30: 0000 cd80 50eb 3159 8b11 8d49 0489 c3b8  ....P.1Y...I....
> 003db40: 0400 0000 cd80 5bb8 0600 0000 cd80 8d1c  ......[.........
> 003db50: 2431 d252 538d 0c24 b80b 0000 00cd 8031  $1.RS..$.......1
> 003db60: dbb8 0100 0000 cd80 e8ca ffff ff46 0100  .............F..
> 003db70: 007f 454c 4601 0101 0000 0000 0000 0000  ..ELF...........
> 003db80: 0002 0003 0001 0000 0054 8004 0834 0000  .........T...4..
> 003db90: 0000 0000 0000 0000 0034 0020 0001 0000  .........4. ....
> 003dba0: 0000 0000 0001 0000 0000 0000 0000 8004  ................
> 003dbb0: 0800 8004 08f2 0000 00f2 0000 0007 0000  ................
> 003dbc0: 0000 1000 0055 89e5 83ec 106a 006a 016a  .....U.....j.j.j
> 003dbd0: 028d 0c24 bb01 0000 00b8 6600 0000 cd80  ...$......f.....
> 003dbe0: 83c4 0c89 45fc 687f 0000 0168 0200 0438  ....E.h....h...8
> 003dbf0: 8d14 246a 1052 508d 0c24 bb03 0000 00b8  ..$j.RP..$......
> 003dc00: 6600 0000 cd80 83c4 1485 c07d 186a 006a  f..........}.j.j
> 003dc10: 018d 1c24 31c9 b8a2 0000 00cd 8083 c408  ...$1...........
> 003dc20: ebc4 8b45 fc83 ec20 8d0c 24ba 0300 0000  ...E... ..$.....
> 003dc30: 8b5d fcc7 0105 0100 00b8 0400 0000 cd80  .]..............
> 003dc40: ba04 0000 00b8 0300 0000 cd80 c701 0501  ................
> 003dc50: 0001 c741 04c0 a801 0166 c741 0815 b3ba  ...A.....f.A....
> 003dc60: 0a00 0000 b804 0000 00cd 80ba 2000 0000  ............ ...
> 003dc70: b803 0000 00cd 8083 c420 8b5d fcb9 0200  ......... .]....
> 003dc80: 0000 b83f 0000 00cd 8049 7df6 31d2 682d  ...?.....I}.1.h-
> 003dc90: 6900 0089 e768 2f73 6800 682f 6269 6e89  i....h/sh.h/bin.
> 003dca0: e352 5753 8d0c 24b8 0b00 0000 cd80 31db  .RWS..$.......1.
> 003dcb0: b801 0000 00cd 80b8 0100 0000 c3fd ffff  ................

Datamining

info.sh

The info.sh script allows listing mitigations on the firmare in the current folder.

$ info.sh -h
Display/save mitigations and additional info for all firmware in the current folder
Usage: info.sh [--save-result --db-name <json_db>]

Once you have extracted all firmware, you can analyse them:

fw$ ls
_asa802-k8.bin.extracted         _asa825-51-k8.bin.extracted      _asa844-5-k8.bin.extracted    _asa911-4-k8.bin.extracted    _asa922-4-k8.bin.extracted        _asa944-smp-k8.bin.extracted
_asa803-k8.bin.extracted         _asa825-52-k8.bin.extracted      _asa844-9-k8.bin.extracted    _asa911-k8.bin.extracted      _asa922-4-smp-k8.bin.extracted    _asa951-smp-k8.bin.extracted
_asa804-16-k8.bin.extracted      _asa825-57-k8.bin.extracted      _asa844-k8.bin.extracted      _asa911-smp-k8.bin.extracted  _asa922-k8.bin.extracted          _asa952-smp-k8.bin.extracted
_asa804-k8.bin.extracted         _asa825-59-k8.bin.extracted      _asa845-k8.bin.extracted      _asa912-k8.bin.extracted      _asa923-k8.bin.extracted          _asa953-smp-k8.bin.extracted
_asa805-23-k8.bin.extracted      _asa825-k8.bin.extracted         _asa845-smp-k8.bin.extracted  _asa912-smp-k8.bin.extracted  _asa923-smp-k8.bin.extracted      _asa961-10-smp-k8.bin.extracted
_asa805-28-k8.bin.extracted      _asa825-smp-k8.bin.extracted     _asa846-5-k8.bin.extracted    _asa913-k8.bin.extracted      _asa924-10-k8.bin.extracted       _asa961-smp-k8.bin.extracted
_asa805-31-k8.bin.extracted      _asa831-k8.bin.extracted         _asa846-k8.bin.extracted      _asa913-smp-k8.bin.extracted  _asa924-13-smp-k8.bin.extracted   _asa962-3-smp-k8.bin.extracted
_asa805-k8.bin.extracted         _asa831-smp-k8.bin.extracted     _asa846-smp-k8.bin.extracted  _asa914-5-k8.bin.extracted    _asa924-14-k8.bin.extracted       _asa962-smp-k8.bin.extracted
_asa811-smp-k8.bin.extracted     _asa832-13-k8.bin.extracted      _asa847-15-k8.bin.extracted   _asa914-k8.bin.extracted      _asa924-18-k8.bin.extracted       _asa971-smp-k8.bin.extracted
_asa812-23-smp-k8.bin.extracted  _asa832-25-k8.bin.extracted      _asa847-26-k8.bin.extracted   _asa914-smp-k8.bin.extracted  _asa924-5-k8.bin.extracted        _asav932-200.qcow2.extracted
_asa812-49-smp-k8.bin.extracted  _asa832-39-k8.bin.extracted      _asa847-28-k8.bin.extracted   _asa915-12-k8.bin.extracted   _asa924-5-smp-k8.bin.extracted    _asav933-10.qcow2.extracted
_asa812-50-smp-k8.bin.extracted  _asa832-40-k8.bin.extracted      _asa847-29-k8.bin.extracted   _asa915-16-k8.bin.extracted   _asa924-8-k8.bin.extracted        _asav933-11.qcow2.extracted
_asa812-55-smp-k8.bin.extracted  _asa832-44-k8.bin.extracted      _asa847-30-k8.bin.extracted   _asa915-19-k8.bin.extracted   _asa924-8-smp-k8.bin.extracted    _asav933-9.qcow2.extracted
_asa812-56-smp-k8.bin.extracted  _asa832-44-smp-k8.bin.extracted  _asa847-31-k8.bin.extracted   _asa915-21-k8.bin.extracted   _asa924-k8.bin.extracted          _asav941-13.qcow2.extracted
_asa812-smp-k8.bin.extracted     _asa832-4-k8.bin.extracted       _asa847-k8.bin.extracted      _asa915-k8.bin.extracted      _asa924-smp-k8.bin.extracted      _asav941-200.qcow2.extracted
_asa821-k8.bin.extracted         _asa832-k8.bin.extracted         _asa847-smp-k8.bin.extracted  _asa915-smp-k8.bin.extracted  _asa931-smp-k8.bin.extracted      _asav941-6.qcow2.extracted
_asa822-k8.bin.extracted         _asa832-smp-k8.bin.extracted     _asa861-smp-k8.bin.extracted  _asa916-10-k8.bin.extracted   _asa932-200-smp-k8.bin.extracted  _asav941.qcow2.extracted
_asa822-smp-k8.bin.extracted     _asa841-11-k8.bin.extracted      _asa901-k8.bin.extracted      _asa916-11-k8.bin.extracted   _asa932-smp-k8.bin.extracted      _asav942-6.qcow2.extracted
_asa823-k8.bin.extracted         _asa841-k8.bin.extracted         _asa902-k8.bin.extracted      _asa916-4-k8.bin.extracted    _asa933-11-smp-k8.bin.extracted   _asav942.qcow2.extracted
_asa823-smp-k8.bin.extracted     _asa841-smp-k8.bin.extracted     _asa902-smp-k8.bin.extracted  _asa916-k8.bin.extracted      _asa933-7-smp-k8.bin.extracted    _asav952-204.qcow2.extracted
_asa824-4-k8.bin.extracted       _asa842-8-k8.bin.extracted       _asa903-k8.bin.extracted      _asa916-smp-k8.bin.extracted  _asa933-9-smp-k8.bin.extracted    _asav961.qcow2.extracted
_asa824-k8.bin.extracted         _asa842-k8.bin.extracted         _asa903-smp-k8.bin.extracted  _asa917-12-k8.bin.extracted   _asa933-smp-k8.bin.extracted      _asav962-2.qcow2.extracted
_asa824-smp-k8.bin.extracted     _asa842-smp-k8.bin.extracted     _asa904-38-k8.bin.extracted   _asa917-13-k8.bin.extracted   _asa941-13-smp-k8.bin.extracted   _asav962-7.qcow2.extracted
_asa825-13-k8.bin.extracted      _asa843-8-k8.bin.extracted       _asa904-39-k8.bin.extracted   _asa917-4-k8.bin.extracted    _asa941-smp-k8.bin.extracted      _asav962.qcow2.extracted
_asa825-22-k8.bin.extracted      _asa843-k8.bin.extracted         _asa904-40-k8.bin.extracted   _asa917-6-k8.bin.extracted    _asa942-11-smp-k8.bin.extracted   _asav971.qcow2.extracted
_asa825-26-k8.bin.extracted      _asa843-smp-k8.bin.extracted     _asa904-42-k8.bin.extracted   _asa917-9-k8.bin.extracted    _asa942-6-smp-k8.bin.extracted
_asa825-33-k8.bin.extracted      _asa844-1-k8.bin.extracted       _asa904-5-k8.bin.extracted    _asa917-k8.bin.extracted      _asa942-smp-k8.bin.extracted
_asa825-41-k8.bin.extracted      _asa844-1-smp-k8.bin.extracted   _asa904-k8.bin.extracted      _asa921-k8.bin.extracted      _asa943-12-smp-k8.bin.extracted
_asa825-46-k8.bin.extracted      _asa844-3-k8.bin.extracted       _asa904-smp-k8.bin.extracted  _asa921-smp-k8.bin.extracted  _asa943-smp-k8.bin.extracted
fw$ info.sh --save-result --db-name /path/to/asafw/asadb.json

A database with already a bunch of firmware version is provided in the repo as asadb.json.

If you simply want to list the mitigations, you simply go to the root folder containing all the extracted firmware and use it without any argument:

$ info.sh

info.py

The following script is used by info.sh to fill a json database.

$ info.py -h
usage: info.py [-h] [-l] [-u UPDATE_INFO] [-i BIN_NAME] [-v VERBOSE]
               [-d DBNAME]

optional arguments:
  -h, --help      show this help message and exit
  -l              List migitations in all firmware versions
  -u UPDATE_INFO  Output from info.sh to update db
  -i BIN_NAME     firmware bin name to update or display
  -v VERBOSE      display more info
  -d DBNAME       json database name to read/list info from

Outside of its use by info.sh, its main interest is using the following command to display the summary of mitigations:

asafw$ info.py -l asadbg.json

Note that info.py -l can also be used to get the index (first column) of a specific version in case it is required (e.g. for lina.py).

Mitigation summary

Below is a copy of the output of info.py -l -d asadbg.json, formatted correctly for markdown:

End-of-life ASA versions

To our knowledge there isn't any summary of ASA branches being End-of-life (EOL)

• though an official list of EOL devices is here. Feel free to contact us if we are missing something. However, it is possible to use the Cisco ASA advisories here to deduce branch EOL status. Last update of this table is July 2017.

Known issues

sudo -E not keeping the PATH

On Ubuntu 18.04 at least, they have a defined secure_path in /etc/sudoers which forbids using the sudo -E command:

$ unpack_repack_qcow2.sh
[unpack_repack_qcow2] You need to be root to mount/unmount the qcow2
$ sudo -E unpack_repack_qcow2.sh
[sudo] password for user:
sudo: unpack_repack_qcow2.sh: command not found

So you may need to comment that out, see here.

#Defaults	secure_path="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin"

$ sudo -E unpack_repack_qcow2.sh 
[sudo] password for user: 
[unpack_repack_qcow2] ERROR: You must specify at least a valid -i file: 
[unpack_repack_qcow2] ERROR: Double check your working directory as  doesn't appear to exist