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BLATSTING
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Wladimir van der Laan 2016. This document is in the public domain. | |
BLATSTING reverse-engineering notes. Based on files from the EQGRP free dump, | |
more specifically in Firewall/BLATSTING/BLATSTING_201381/LP/lpconfig. | |
In https://musalbas.com/2016/08/16/equation-group-firewall-operations-catalogue.html, | |
BLATSTING is described as "A firewall software implant that is used with EGREGIOUSBLUNDER | |
(Fortigate) and ELIGIBLEBACHELOR (TOPSEC)". | |
If true, it's interesting how this implant can target both vendors. Presumably they both use the same Linux | |
kernel version (2.4.x = FortiOS 5.2). Possibly, one series of network devices is a "whitelabel" variant of the other. | |
Ironically they have both been part of GPL disputes: | |
- https://osdir.com/ml/law.gpl.violations.technical/2006-05/msg00007.html | |
> TOPSEC is a chinese security provider that provide firewall based Linux and netfilter... claims the | |
> entire software is (C) Copyright TOPSEC | |
- https://en.wikipedia.org/wiki/Gpl-violations.org#Fortinet | |
> In 2005, the gpl-violations.org project uncovered evidence that Fortinet had used GPL code in | |
> its products against the terms of the license, and used cryptographic tools to conceal the violation. | |
The source code (including their modified kernel) is still available: | |
http://laforge.gnumonks.org/blog/20050522-fortinet-sourcecode/ . This does not exactly match the kernel | |
that is targetted by the rootkit, but with regard to structure offsets it is closer than | |
2.4.x stock kernels. | |
What is BLATSTING? | |
====================== | |
BLATSTING is a toolkit that is to be installed after exploitation, to have a foothold | |
on a router. It could be installed through a backdoor or exploit, but this is | |
not part of BLATSTING proper but the stage that preceeds it. BLATSTING, as far as I've | |
noticed, contains no exploits. | |
Basically it is a Linux rootkit that loads into the kernel. To what it does | |
there is no single answer as it can differ based on which modules are loaded. A | |
few (possibly not all) of these modules are part of the dump. Some of them deal | |
with network traffic interception or statistics, another one, SECONDDATE can do | |
MiTM attacks, yet another one TADAQUEOUS can selectively weaken IPsec VPN | |
encryption. And so on. It can be controlled through the network. | |
Overview | |
=============== | |
BLATSTING "modular rootkit" implant modules | |
(not showing implied dependencies, e.g. everything depends on core mod) | |
┌───────────┐ | |
│ m00000003 │ | |
│ core │ | |
└─────┬─────┘ | |
┆ | |
┌┄┄┄┄┄┄┄┄┄┄┄┄┄┬┄┄┄┄┄┄┄┄┄┄┄┄┄┄┬┄┄┄┄┄┴┄┄┄┄┄┄┄┬┄┄┄┄┄┄┄┄┄┄┄┄┄┬┄┄┄┄┄┄┄┄┄┄┄┄┄┐ | |
v v v v v v | |
┌─────┴─────┐ ┌─────┴──────┐ ┌─────┴─────┐ ┌─────┴─────┐ ┌─────┴─────┐ ┌─────┴─────┐ | |
│ m01010001 │ │ m01020000 │ │ m0c010001 │ │ m03010000 │ │ m05000003 │ │ m08010001 │ | |
│ crypto │ │ crypto_rsa │ │ bpf │ │ network │ │ install │ │ hash │ | |
└─────┬─────┘ └──────┬─────┘ └─────┬─────┘ └─┬──┬─┬────┘ └─┬───┬──┬──┘ └───────────┘ | |
┆ ┆ ┆ ┆ ┆ ┆ ┆ ┆ ┆ | |
└┄┄┄┄┄┄┄┄┄┄┄┄┬┄┘ ┆ ┆ ┆ ┆ ┆ ┆ ┆ | |
┆ ┆ ┆ ┆ ┆ ┆ ┆ ┆ | |
┌┄┄┄┄┄┄┄┄┄┄┄ ┆ ┄┄┄┄┄┄┬┄┄┄┄┄┄┄┴┄┄┄┄┄┄┄┄┄┴┄ ┆ ┆ ┄┄┄┄┄┄┄┘ ┆ └┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┐ | |
┆ ┆ ┆ ┆ ┆ ┆ ┆ | |
┆ ┆ ┆ ┆ └┄┄┄┄┄┄┄┄┄┄┄┄┴┄┄┄┄┄┄┄┄┄┄┐ ┆ | |
┆ ┆ ┆ ┆ ┆ ┆ | |
┆ ┆ ┆ ┌┄┄┴┄┄┄┄┄┄┄┄┄┐ ┆ ┆ | |
v ┆ v v v v v | |
┌─────┴───────────┐┆ ┌─────┴─────┐ ┌───────┴────┐ ┌─────┴─────┐ ┌───────┴───┐ ┌─────┴─────┐ | |
│ m0d000001 │┆ │ m10000001 │ │ m0e000001 │ │ m07000001 │ │ m09000002 │ │ m02000001 │ | |
│ networkProfiler │┆ │ sniffer │ │ seconddate │ │ cnc │ │ tunnel │ │ file │ | |
└─────────────────┘┆ └───────────┘ └────────────┘ └───────────┘ └───────────┘ └─────┬─────┘ | |
┆ ┆ | |
└┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┬┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┘ | |
v | |
┌─────┴──────┐ | |
│ m12000000 │ | |
│ tadaqueous │ | |
└────────────┘ | |
General notes | |
================= | |
- It is quickly apparent that BLATSTING is meant to run inside the Linux kernel. Various | |
referenced symbol such as `skb_linearize` point in this direction. | |
- All addresses within modules mentioned in this document are of the form 0x08xxxxxx, where xxxxxx is the | |
literal offset within the ELF part of the .impmod file. This is the same offset that Radare2 shows. | |
Interfaces | |
============ | |
All interfaces are represented by a function call table (a list of pointers to .text segment, | |
prefixed with the interface ID and the module ID). | |
|modid | name | imports (requires) | exports | | |
|---------|-----------------|-----------------------------------------|---------------------| | |
|m00000003| core | | i00000003 | | |
|m01010001| crypto | i00000003 | i01010000 | | |
|m01020000| crypto_rsa | i00000003 | i01020000 | | |
|m0c010001| bpf | i00000003 | i0c010000 | | |
|m03010000| network | i00000003 | i03010001 i11000000 | | |
|m05000003| install | i00000003 | i05000000 | | |
|m08010001| hash | i00000003 | i08010000 | | |
|m0e000001| seconddate | i00000003 i03010001 | | | |
|m02000001| file | i00000003 i05000000 | i02000000 i04000000 | | |
|m0d000001| networkProfiler | i00000003 i03010001 i05000000 i0c010000 | i0d000000 | | |
|m09000002| tunnel | i00000003 i03010001 i05000000 | i09000000 | | |
|m10000001| sniffer | i00000003 i03010001 i05000000 i0c010000 | i10000000 | | |
|m07000001| cnc | i00000003 i03010001 | i07000000 | | |
|m12000000| tadaqueous | i00000003 i01010000 i01020000 i04000000 | | | |
|---------|-----------------|-----------------------------------------|---------------------| | |
- `the_interface` is a pointer to the main interface of the modules to the outside world. It is part of the `core` | |
module, and points to a table of function pointers (and sometimes data fields). Modules register their own | |
interface(s) using `call *(*the_interface+0x40)`. Other modules (which depend on this interface) can then request this | |
interface and use it. | |
A note on interface and module naming | |
-------------------------------------- | |
Module and interface IDs, although conceptually in a different namespace, use the same kind of 32-bit "names". | |
In the module filenames these are represented as 8-byte hexadecimal strings. Internally they are handled in the | |
following way: | |
0 1 2 3 byte | |
┌──┬──┬─────┐ | |
│A │B │ C │ | |
└──┴──┴─────┘ | |
A uint8 mod_type | |
B uint8 intra_mod_type | |
C uint16 version | |
The consequence of this is that the last two bytes will appear swapped in memory. E.g. for mod_crypto: | |
m01010001 Module ID filename | |
0x01 0x01 0x01 0x00 Appears like this in memory (little endian) | |
0x00010101 The above interpreted as uint32 | |
To distinguish module IDs and interface IDs separate the convention mXXXXXXXX for module IDs and | |
iXXXXXXXX for interface IDs is used. | |
0xff or 0xffff in one or more of the three fields is used as a wildcard when requesting interfaces. | |
Kernel injection | |
================== | |
There is an executable `./Firewall/BLATSTING/BLATSTING_20322/sei/cored`, which is the loader for BLATSTING (although an | |
older version than the one analyzed here). It is the only file, apart from the `core` module which contains the | |
mysterious symbol `UYO8_U7c5D`. It also contains the symbol `UWV1S` in obfuscated form, also | |
referenced in other modules. | |
╔════════════════╗ ╔════════════════╗ | |
║ kernel ║ ║ cored ║ | |
╟┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄╢ ╟┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄╢ | |
║ ║ ║ ║ | |
║ Symbol table ───────────> Symbols hash ║ | |
║ ║ ║ table ║ | |
║ ║ ║ ║ | |
║ Syscall table <───────── Hook syscall ║ | |
║ ^ ║ ║ 137 ║ | |
║ │ ║ ║ ║ | |
║ v ║ ║ ║ | |
║ Injected <──────────── .data ║ | |
║ code ║ ║ ║ | |
╚════════════════╝ ╚════════════════╝ | |
The executable `./Firewall/BLATSTING/BLATSTING_20322/sei/cored` performs Linux kernel injection, | |
and appears to host the other modules. | |
Some notes on what it does: | |
- Uses `setrlimit` system call with `RLIMIT_CORE` to prevent dumping core files (avoid leaving evidence). Exit if this fails. | |
- Swap is disabled later on with the sys_swapoff system call. Possibly for a similar reason. | |
- Get the kernel version (`/proc/version` as well as `/proc/sys/kernel/version`). Pad up to 256 bytes and compute SHA1 hash | |
(what is this used for?). Exit if this fails. | |
- Looks in `/data/.tos_cores/` for `b%03x%03x.%03x` and `bs%03x%03x.%03x` files, where | |
the %...x is prinf syntax. These appear to be modules and data files respectively. | |
- First, a configuration file is read, bse226a3.f24. This directs it to open other | |
modules and load them in to memory. | |
- If opening the configuration file fails it tries to look inside the executable itself | |
for information and modules. | |
- The SHA1 hash computed earier of /proc/version || /proc/sys/kernel/version is compared against | |
a predefined set of hashes: | |
d66347bcad1c62daba8f3683251bf60d09d34a01 | |
3c1084e94c1679223269deb81882e8ccd8fffcc4 | |
6bd6cc8e463ce36e843af9325bc9bbd4989bdc02 | |
13b20dfe138cc894e273c10414ad1c2bd1c536c0 | |
Each of these is associated with a two parameter words that are used later in the injection process. | |
The set of hashes, as well as a 663-byte configuration area is read from the end of the executable. | |
Likely there exists an off-line configuration utility to prepare the executable for a certain target | |
kernel and environment. | |
- See also `BLATSTING_20040/utils/procversionhashmaker`, an utility described as | |
"Get the hash bpinsmod uses during implant load." | |
- One of these parameters is the kernel-space base address. | |
If none of them matches the proces exits (with return code 26). | |
- It finds `Kernel code` and `Kernel data` in `/proc/iomem`. | |
- Then mmaps `/dev/mem` directly. It maps the range encompassing kernel code and kernel data. | |
Note that this trick to gain access to kernel space is no longer possible in kernels newer | |
than about 2009 (see http://lwn.net/Articles/267427/) at least if NONPROMISC_DEVMEM, | |
nowadays called CONFIG_STRICT_DEVMEM is enabled. All distributions enable this on x86, that I know of. | |
This points at the age of this software. Newer loaders may exist that use an alternative mechanism. | |
- Looks for symbol `__tos_kmalloc` in the kernel. This is not a stock kernel symbol. I suspect | |
it is specific to TopSec/TOS? There are no Google hits on this symbol at all. | |
- Without finding this symbol, or finding the rest of the symbol table, the program exits with code 4. | |
- Creates a hash table of kernel symbols. | |
- Looks for various symbols in the kernel, mostly associated with memory management. | |
- It seems to hook a syscall interface at some point, and communicate through syscall 137 | |
(`sys_afs_syscall`/`sys_ni_syscall`, a reserved value). | |
- There is a minimal ELF-loader, which is used to load and relocate the modules. After loading | |
the modules, along with initialization data, are copied to kernel memory, then | |
exported symbol `init_bp_module` is called. | |
Modules | |
========= | |
Modules on the implant side usually communicate with a respective module on the lp (listening post) side. | |
Listening post is lingo for a server that runs the control side of the implant. | |
All control communication with the implant goes through the `cnc` module, which sends and receives packets through | |
the `network` module. | |
╔═══════════════════╗ ╔═══════════╗ | |
║ implant ║ ║ lp ║ | |
╟───────────────────╢ UDP ╟───────────╢ | |
║ ┌──────┐ ┌─┐ ┌─┐ ║ network ║ ┌───────┐ ║ | |
║ │impmod│<╌│c│╌│n│<╌╌╌╌╌╌╌╌╌╌╌>│ lpmod │ ║ | |
║ └──────┘ │n│ │e│ ║ ║ └───────┘ ║ | |
║ ┌──────┐ │c│ │t│ ║ ║ ┌───────┐ ║ | |
║ │impmod│<╌│ │╌│ │<╌╌╌╌╌╌╌╌╌╌╌>│ lpmod │ ║ | |
║ └──────┘ └─┘ └─┘ ║ ║ └───────┘ ║ | |
║ ... ║ ║ ... ║ | |
╚═══════════════════╝ ╚═══════════╝ | |
There are two exceptions to this: `seconddate` and `tadaqueous`. These do not interface with `cnc` but with | |
`network` directly, and have their own protocol for command and control. | |
| modid | modulename | imp | lp | | |
|-----------|-----------------|-----|-----| | |
| m00000003 | core | ✓ | ✓ | | |
| m01010000 | crypto | ✕ | ✓ | | |
| m01010001 | crypto | ✓ | ✕ | | |
| m01020000 | crypto_rsa | ✓ | ✓ | | |
| m02000000 | file | ✕ | ✓ | | |
| m02000001 | file | ✓ | ✕ | | |
| m03010000 | network | ✓ | ✕ | | |
| m03010001 | network | ✕ | ✓ | | |
| m04000000 | process | ✕ | ✓ | | |
| m05000000 | install | ✕ | ✓ | | |
| m05000003 | install | ✓ | ✕ | | |
| m06000000 | beacon | ✕ | ✓ | | |
| m06000001 | beacon | ✕ | ✕ | | |
| m07000000 | cnc | ✕ | ✓ | | |
| m07000001 | cnc | ✓ | ✕ | | |
| m08010000 | hash | ✕ | ✓ | | |
| m08010001 | hash | ✓ | ✕ | | |
| m09000000 | tunnel | ✕ | ✓ | | |
| m09000002 | tunnel | ✓ | ✕ | | |
| m0c010000 | bpf | ✕ | ✓ | | |
| m0c010001 | bpf | ✓ | ✕ | | |
| m0d000000 | networkProfiler | ✕ | ✓ | | |
| m0d000001 | networkProfiler | ✓ | ✕ | | |
| m0e000001 | seconddate | ✓ | ✕ | | |
| m10000000 | sniffer | ✕ | ✓ | | |
| m10000001 | sniffer | ✓ | ✕ | | |
| m11000000 | arp | ✕ | ✓ | | |
| m12000000 | tadaqueous | ✓ | ✕ | | |
|-----------|-----------------|-----|-----| | |
Each mXXXXXXXX directory contains one of, or both of: | |
- An `impmod` file which is an ELF file embedded in a special format. To be loaded at | |
the implant side. | |
- An `lpmod` file which is an ELF dynamic library loaded by a 'listening post' backend, which is | |
the command-and-control side of things. These communicate with the associated module | |
at the implant side. | |
## IMPlant MODules | |
- These are loaded into the kernel, but are not Linux kernel modules themselves. A custom loader is used. They lack | |
the information and symbols normally associated with Linux kernel modules. | |
- The format describes the module ID, as well as the interfaces exported and imported by the module. | |
The latter determine the dependency relationships between modules. All modules depend on `core`, | |
which has module ID `m00000003` and exports the core interface `i00000003`. | |
- Symbols: | |
- `the_interface`: The core interface (`i00000003`) - only exported by core module | |
- `UWV1S`/`UVW1S`: Unknown - exported by `cored`, used by the install module. The | |
name of these symbols is chosen somewhat clever: designed to not stand out in hexdumps/ | |
strings, as they look like the typical x86 "push ebp..." function prelude. However adding the '1' | |
character makes it invalid as instructions and unique and easy to grep for. | |
- `UYO8_U7c5D`: OS information/parameters structure - exported by `cored` | |
- `init_bp_module`: Initialization function - exported by every module | |
- `cleanup_bp_module`: Deinitialization function - exported by every module | |
- `cleanup_core_module`: Deinitialization function - exported by core module | |
- One module, `tadaqueous`, has two ELF files embedded. The first one | |
is a module as normal, the other is an executable. | |
Missing modules? | |
----------------- | |
For the following known modules there is no impmod in the dump: | |
- m06000001 beacon (FEINTCLOUD) | |
- m11000000 arp (no separate impmod, but the interface is exported by 'network' module) | |
- ????????? testing | |
- m04000000 process (no separate impmod, but the interface is exported by 'file' module) | |
- ????????? syscall | |
- ????????? persist | |
What do the modules do? | |
========================= | |
m00000003 core | |
--------------------- | |
Exposes functionality to interface with the kernel and host process, register | |
and unregister interfaces, do memory allocation and de-allocation, and hook kernel | |
functions. | |
- Besides initializing internal data structures it creates a kernel thread on initialization. | |
- This thread looks through task structures, and find the task structure for process 1 (init). | |
- Then it reparents to init. | |
- It does a few modifications in the thread's task_struct, based on that of init. | |
I suspect this is to hide the rootkit, but lack of the kernel attacked makes it hard to | |
interpret what is being done. | |
- The thread then goes into a loop. | |
- On module cleanup the thread is stopped. This rootkit does attempt to neatly clean up after itself. | |
m01010001 crypto | |
--------------------- | |
Symmetric cryptography functions. This module implements RC6 in Output Feedback (OFB) mode, | |
with 128-bit blocksize and 20 rounds: | |
- Various hints in the dump point at this being a favorite of EQGRP | |
- The encryption and decryption routines are the same. | |
- The constants 0xb7e15163 and 0x61c88647 are used in the same way as described in chapter 16 of | |
https://securelist.com/files/2015/02/Equation_group_questions_and_answers.pdf However, this is supposedly false alarm | |
according to https://www.cs.uic.edu/~s/musings/equation-group-rc6/. | |
- I verified the results of encrypting using this module against radare's RC6 implementation, and it matches. | |
m01020000 crypto_rsa | |
--------------------- | |
RSA cryptography functions. See https://laanwj.github.io/2016/09/13/blatsting-rsa.html . | |
m0c010001 bpf | |
--------------------- | |
Berkeley Packet Filter functionality. BPFs are programs for a simple | |
virtual machine that can inspect(among other things) network packets, | |
and accept or reject them. | |
Expressions in network sniffers such as pcap are often compiled to this | |
representation (in fact, pcap is being used as compiler at the lp side). | |
See also: | |
- https://blog.cloudflare.com/bpf-the-forgotten-bytecode/ | |
- https://www.kernel.org/doc/Documentation/networking/filter.txt | |
It looks like this module implements a dialect of BPF, not the same | |
BPF as used in the Linux kernel. Instructions are still 8 bytes and have the | |
same global format, however while trying to decompile the predefined filters | |
there are 4xxx instructions that are different from normal BPF instructions: | |
4027 OUTB Write byte to output buffer at offset k | |
402f OUTH Write half-word to output buffer at offset k | |
4037 OUTW Write word to output buffer at offset k | |
Also a BPF_MODE is added | |
BPF_CNT = 0xc0 # LD/LDX only: Read counter k | |
These have to do with the goal bpf is used for in `networkProfiler`, which | |
extracts information from packets instead of filtering them. A quick look at the | |
function responsible for evaluating bpf programs (0x08000034) shows that there | |
are more 4xxx and 2xxx extension instructions than these. | |
m03010000 network | |
--------------------- | |
Network functionality. Exposes two interfaces. One is `network` (i03010001), which is used by | |
other modules to access the network, the other is `arp` (i11000000) which does not offer any functionality | |
to modules, but can be controlled remotely. | |
- Hooks kernel function `netif_rx` at initialization to intercept all incoming network traffic, | |
and unhooks it at cleanup. All network packets dispatched in the Linux kernel go through this function, | |
so hooking it is the operating system equivalent of a Room 641A within your kernel. | |
- Tries to request the bpf interface at initialization, but this is not a hard dependency. | |
m05000003 install | |
--------------------- | |
Installation/persistence? | |
m08010001 hash | |
--------------------- | |
Apparent from some of the constants in the code (0x5a827999, 0xca62c1d6) this implements | |
the SHA1 hashing algorithm. It does, but with a twist that it only gives the correct output | |
when input size is congruent to 0 mod 4. See below under "Trivia". | |
This is the only hash algorithm implemented. The equivalent module in BUZZDIRECTION happens to | |
also implement SHA256. | |
Note that there are no consumers that require interface i08010000. The cnc module tries to aquire | |
it but it won't fail if it can't. | |
m0e000001 seconddate | |
--------------------- | |
This is by far the most interesting, also the largest binary. | |
- SECONDDATE is an exploitation technique that takes advantage of web-based protocols and man-in-the-middle (MitM) | |
positioning. | |
- SECONDDATE influences real-time communications between client and server and can quietly redirect web-browsers to | |
FOXACID servers for individual client exploitation. | |
- This allows mass exploitation potential for clients passing through network choke points, but is configurable to | |
provide surgical target selection as well. | |
From: https://edwardsnowden.com/2014/03/12/willowvixen-and-seconddate/ (third slide). | |
See https://gist.github.com/laanwj/96841340cecb5ada220af39551df2896#file-seconddate-3-1-1-0-c-L119 for a | |
few data structures that are likely used in communication with this module. Like tadaqueous, it does not implement a | |
normal endpoint for BLATSTING cnc. | |
A complete regexp-compiling and matching engine is embedded in in this module (apparently PCRE). This is used to look | |
for the famous string 'ace02468bdf13579' (https://theintercept.com/2016/08/19/the-nsa-was-hacked-snowden-documents-confirm/), | |
match HTTP in TCP streams '^GET.*(?:/ |\\.(?:htm|asp|php)).*\\r\\n\x00', as well as look for user-defined patterns. | |
SECONDDATE is not controlled through BLATSTING's C&C mechanism but has it's own command-and-control system. In the | |
EQGRP-free dump there are separate executables for the LP side. More about SD's C&C protocol can be found here: | |
http://laanwj.github.io/2016/09/17/seconddate-cnc.html . | |
m02000001 file | |
--------------------- | |
Exports two interfaces: `file` (i02000000) provides file operations, `process` | |
(i04000000) provides process control operations. | |
File operations: | |
- Hide a file | |
- Unhide a file | |
- Read a file from the target | |
- Write a file to the target | |
Process operations: | |
- List hidden process IDs | |
- Execute a process | |
m0d000001 networkProfiler | |
-------------------------- | |
Execute predefined or custom (passive) scans based on BPF rules, collect statistics. | |
See e.g. `Firewall/BLATSTING/BLATSTING_201381/LP/lpconfig/m0d000000/predefinedScans`. These files contain a description | |
of the filter, and a compiled BPF program in binary form. | |
networkProfiler acts like a network sniffer, but instead of storing every packet it creates statistics based on | |
information extracted from each packet, such as source and destination IP. This is fully programmable. | |
How this works is that basic BPF opcode set is extended with opcodes to write to an output buffer. Part of this output | |
buffer is used as key into a hash table, the other part consists of the value, usually counters (counting packets, | |
bytes, etc). Statistics "records" are thus accumulated per key. This is similar to what e.g. the `iptraf` utility for | |
Linux does (http://iptraf.seul.org/shots/iptraf-iptm1.gif), except more stealthy. | |
The LP module allows setting the following command line: | |
``` | |
-S/--scantype <scan name> name of predefined scan (enter ? to be provided with a list) | |
-i/--interface <interface index (as from interface listing)> limit to the specified interface | |
-t/--traffictypes <traffic queue flags> receive traffic of the specified types only (enter ? to be provided with a list) | |
-P/--prefilter netmask <netmask length> netmask length for prefilter (0-32, default 0) | |
-p/--prefilter <pcap filter string> pcap pre-filter definition (enclose this in double quotes) | |
-s/--duration_seconds <seconds> test duration in seconds | |
-m/--duration_minutes <minutes> test duration in minutes | |
-r/--duration_hours <hours> test duration in hours | |
-y/--duration_days <days> test duration in days | |
-N/--nperiods <# of scan periods> number of periods to scan (default: 1) | |
-n/--maxNRecords <# of records> maximum number of records to keep per period | |
--hashTableSize <# of entries> size of the hash table | |
-h/--help print this usage message | |
``` | |
See also https://laanwj.github.io/2016/09/09/blatsting-lp-transcript.html . | |
m09000002 tunnel | |
--------------------- | |
NAT tunneling, packet forwarding and redirection. Likely, this is used to reach | |
targets behind the router. | |
The LP module allows setting the following command line: | |
``` | |
You will be asked to enter both IP addresses and port numbers for | |
the outside source and destination and the inside source and destination. | |
Please enter all parameters as if for a packet which is traveling towards | |
the inside network. | |
outside source, dest <-tunnel-> inside source, dest | |
IP addresses are entered in the form #.#.#.#/<netmask>. | |
Please enter your tunnel command line (-h for help, CTRL-n to cancel)? -h | |
-S/--outsidesrc <#.#.#.#/#> outside source IP address | |
-D/--outsidedst <#.#.#.#/#> outside destination IP address | |
-s/--insidesrc <#.#.#.#/#> inside source IP address | |
-d/--insidedst <#.#.#.#/#> inside destination IP address | |
-P/--outsidesrcport0 <port> outside source port 0 | |
--outsidesrcport1 <port> outside source port 1 | |
--outsidesrcport2 <port> outside source port 2 | |
--outsidesrcport3 <port> outside source port 3 | |
-Q/--outsidedstport0 <port> outside destination port 0 | |
--outsidedstport1 <port> outside destination port 1 | |
--outsidedstport2 <port> outside destination port 2 | |
--outsidedstport3 <port> outside destination port 3 | |
-p/--insidesrcport0 <port> inside source port 0 | |
--insidesrcport1 <port> inside source port 1 | |
--insidesrcport2 <port> inside source port 2 | |
--insidesrcport3 <port> inside source port 3 | |
-q/--insidedstport0 <port> inside destination port 0 | |
--insidedstport1 <port> inside destination port 1 | |
--insidedstport2 <port> inside destination port 2 | |
--insidedstport3 <port> inside destination port 3 | |
-N/--nat this is a NAT tunnel | |
--hopcount <integer> amount to decrement the hop count by on each pass (default: 2) | |
-l/--lifetime <seconds> tunnel lifetime (default: tunnel is immortal (0)) | |
-t/--timeout <seconds> active connection timeout (default: 30 seconds) | |
--nochecksum transport checksum correction off | |
-y/--priority <priority> priority (default: calculated) | |
-b/--blackhole blackhole (packet-eating tunnel) [expert only] | |
-h/--help print this usage message | |
``` | |
m10000001 sniffer | |
--------------------- | |
Sniff network traffic. | |
This can capture whole packets or certain segments of them. Uses BPF to pre-filter. | |
Due to limited space on the device this either uses a ring buffer, which needs | |
to be periodically polled by the lp to make sure that everything is captured, or | |
a fixed-size buffer after which the capture will stop. | |
The LP module allows setting the following command line: | |
``` | |
-i/--interface <interface index from interface listing> limit to the specified interface | |
-t/--traffictypes <traffic queue flags> receive traffic of the specified types only (enter ? to be provided with a list) | |
-P/--prefilter netmask <netmask length> netmask length for prefilter (0-32, default 0) | |
-p/--prefilter <pcap filter string> pcap pre-filter definition (enclose this in double quotes) | |
-c/--capturecap <max no. packets> maximum number of packets to capture | |
-b/--bufferlen <buffer length> size of buffer for storing captured packets (in bytes) | |
-s/--snapseg <snapseg> spans of bytes to capture from each packet of the form start-end,start-end up to 8 segments (an end of 0 means to end of packet) | |
-r/--ring set to use a ring buffer, which will overwrite old captured packets | |
-R/--noring set to NOT use a ring buffer, capturing will stop when the buffer is full | |
-H/--printheaders print out the IP and TCP header formats | |
-h/--help print this usage message | |
``` | |
m07000001 cnc | |
--------------------- | |
Command-and-control functions. Receives UDPv4 packets from the network module, | |
if they have the right size and checksum, dispatches them internally. | |
See https://laanwj.github.io/2016/09/04/blatsting-command-and-control.html for more | |
information. | |
Every interface can have a method to process `BF_5i_CALL` RPC requests from the LP. | |
This is always the function at `ifptr + 0x10`. If not defined it can either be 0 | |
or return an error code. Most interfaces do have some calls to support remote | |
control, except base utilities such as `bpf`, `crypto` `hash` and modules that have | |
their own C&C such as `tadaqueous` and `seconddate`. | |
m12000000 tadaqueous | |
--------------------- | |
The non-conventional name seems to apply this is another internal project such as SECONDDATE. | |
And it is: https://laanwj.github.io/2016/09/01/tadaqueos.html . My analysis shows that this module | |
is used for selective IPsec weakening, as well as for disabling the generation of random numbers | |
within the kernel. | |
> If you are putting up tadaqueous, there will be lp error due to a missing files, there is no LP for this module. | |
- quote from Firewall/SCRIPTS/EGBL_AND_BLATSTING.txt (there is, indeed, no lpmod for TADAQUEOUS in the dump) | |
Different from the other impmods, this still contains the .comment section, which reveals that the module | |
is compiled with "GCC: (GNU) 3.2.2 20030222 (Red Hat Linux 3.2.2-5)". | |
Kernel interface | |
==================== | |
After injection into the kernel a spare syscall, number 137 (0x89), is hooked to provide an | |
interface from user space to specific kernel functionality. | |
Register ebx seems to be used to communicate a sub-function, which is one of. | |
0x9d3d143a kernel_alloc(size,flags) | |
0x384713aa copy_to_kernel(kaddr,uaddr,size) | |
0x93b4e2d2 (unk) | |
0xe53c2e96 (unk) | |
0xfd13acf3 kernel_free(addr) | |
Other trivia | |
============== | |
- Various strings in the `cored` executable are obfuscated using a simple substitution | |
cipher. It makes use of multiplication mod 256, which is a clever little trick | |
I've not seen before for obfuscation. For example: multiply with 29 to decrypt then | |
multiply with its multiplicative inverse mod 256, 53, to encrypt again. | |
- The "SHA1" function in `cored` (0x0804ae38) is actually a variant of SHA1. This does cause | |
the output hashes to be completely different. Not sure if they botched this or this is a subtle | |
change on purpose: | |
- Instead of adding 0x80 at the end of the input then padding with zeros, this function | |
processes the input in 4-byte words, and adds 0x80000000 (little-endian) at the end of the | |
input, then pads with zeros. This is before the endian-swap at the beginning of the transform | |
(necessary on little-endian architectures), so for example the buffer for 'test' will end up looking: | |
74 65 73 74 00 00 00 80 <zeros> 00 00 00 00 20 00 00 00 | |
Whereas it would normally be: | |
74 65 73 74 80 ...<zeros>... 00 00 00 00 00 00 00 20 | |
- Also note that the endian of the bit count at the end is flipped per 32-bit unit. | |
- Due to a bug in this padding method, only a multiple of 4 bytes can be processed without | |
ignoring up to three bytes of input. It looks like the function is only used to hash 256 bytes, | |
so this bug does not surface in practice. | |
- However if the `hash` module also implements this variant (it seems that way), and | |
this module is actually used by anything, things are different. | |
- The hash module implements an almost-correct SHA1. The buffer itself is built in the same | |
way as previously, and in the inner function all endian swapping normally required for implementing | |
SHA-1 on little-endian architectures is left out. But this is handled in an outer function, which | |
works around the problems: allocates a new buffer (padded to 4 with zeros), copies the input, endian-swapped | |
intothis new buffer, calls the inner function on this buffer, then frees the buffer, byte-swaps the result | |
and returns that digest. It's kind of circuitous, but for buffers where the size is a multiple of 4 | |
this returns the same as 'normal' SHA1. For other sizes it return a different output due to the padding. | |
- BLATSTING's implementers are a big fan of mmap. It seems to be used for all file access, not just | |
for manipulating kernel memory through `/dev/mem`. Is it done this way to reduce the number | |
of system calls, to be less conspicious, as well as not reveal what exactly is accessed when | |
running in `strace`? Or maybe a later stage of the rootkit blocks certain kinds of syscalls | |
on certain "hidden" files. | |
- While reverse engineering I haven't found any explicit countermeasures or anti-debugging tricks. | |
However: | |
- BLATSTING's implementers took a lot of care not to leak strings that could help with reverse engineering *at the | |
implant side*. This is true for `cored`, but also for the modules themselves. There are no log messages, no debug | |
prints, no error messages, nothing. | |
- The few strings that are absolutely necessary (such as symbol names) are obfuscated. | |
- The code was compiled with `-fomit-frame-pointers` (or similar), which makes it somewhat harder | |
to keep track of the stack frame while reading assembly. | |
- The lp (listening post) side is much more loose: debug printing, spurious symbols (internal functions, | |
bc no -Bsymbolic used), plenty of error messages and other text. | |
- The code of `cored` is a strange mix of static and dynamic linking. For example, at one point it uses | |
a direct `sys_open` syscall to open a file then performs `mmap` through the C library. | |
In the same function. | |
- The abbreviation `bp_` in symbols likely stands for BEECHPONY. According to | |
https://marcoramilli.blogspot.nl/2016/08/summing-up-shadowbrokers-leak.html this is | |
"BEECHPONY A firewall implant that is a predecessor of BANANAGLEE." I haven't looked at | |
BANANAGLEE much but to me it looks like BUZZDIRECTION is a newer version of this framework. | |
It wouldn't surprise me if BLATSTING was the oldest of the bunch. | |
- Another hint that this rootkit is older than BUZZDIRECTION can be found in the hash module: | |
SHA1 is the only hash algorithm implemented. The equivalent module in BUZZDIRECTION happens to | |
also implement SHA256. | |
See also: https://laanwj.github.io/2016/09/11/buzzdirection.html | |
- Looking at the core module, it indeed appears that this rootkit is ancient. The kernel thread | |
spawned by `init_bp_module`, `0x08001384`, relies on the pre-2.6 functionality where the beginning | |
of the kernel stack was the `task_struct` (nowadays it is `thread_info`, a much smaller structure). | |
This means the rootkit will only work on Linux 2.4. There is no way that this is a risk to modern kernels, | |
though some routers in active use may still be based on old kernels such as that. | |
- The offsets inside the `task_struct` don't match any kernel I could find, though a manually compiled | |
2.4.25 kernel came closer than debug symbols I found for an RHEL3 2.4.21 kernel. It looks like | |
this rootkit is specific to an extrememly narrow range of kernel versions. | |
- This does NOT have to mean that the rootkit is ancient: just that the devices it targets are. Third-world | |
countries usually won't have the newest equipment. | |
- The code is written in as platform-independent way as possible. It implements its own ELF loader, its | |
own BPF packet filter (even though Linux has it built-in), uses big-endian in input formats, the network | |
module handles its own ARP, and so on. Like a state within a state this implements an OS within an OS. | |
This has been continued even more strongly with BUZZDIRECTION, which has separate platform and core modules. |
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