health: Agustus 2020

Linux Stack Protection By Default

Modern gcc compiler (v9.2.0) protects the stack by default and you will notice it because instead of SIGSEGV on stack overflow you will get a SIGABRT, but it also generates coredumps.

In this case the compiler adds the variable local_10. This variable helds a canary value that is checked at the end of the function.
The memset overflows the four bytes stack variable and modifies the canary value.

The 64bits canary 0x5429851ebaf95800 can't be predicted, but in specific situations is not re-generated and can be bruteforced or in other situations can be leaked from memory for example using a format string vulnerability or an arbitrary read wihout overflowing the stack.

If the canary doesn't match, the libc function __stack_chck_fail is called and terminates the prorgam with a SIGABORT which generates a coredump, in the case of archlinux managed by systemd and are stored on "/var/lib/systemd/coredump/"

❯❯❯ ./test
*** stack smashing detected ***: terminated
fish: './test' terminated by signal SIGABRT (Abort)

❯❯❯ sudo lz4 -d core.test.1000.c611b7caa58a4fa3bcf403e6eac95bb0.1121.1574354610000000.lz4
[sudo] password for xxxx:
Decoding file core.test.1000.c611b7caa58a4fa3bcf403e6eac95bb0.1121.1574354610000000
core.test.1000.c611b : decoded 249856 bytes

❯❯❯ sudo gdb /home/xxxx/test core.test.1000.c611b7caa58a4fa3bcf403e6eac95bb0.1121.1574354610000000 -q

We specify the binary and the core file as a gdb parameters. We can see only one LWP (light weight process) or linux thread, so in this case is quicker to check. First of all lets see the back trace, because in this case the execution don't terminate in the segfaulted return.

We can see on frame 5 the address were it would had returned to main if it wouldn't aborted.

Happy Idea: we can use this stack canary aborts to detect stack overflows. In Debian with prevous versions it will be exploitable depending on the compilation flags used.
And note that the canary is located as the last variable in the stack so the previous variables can be overwritten without problems.

How To Secure Your Home Against "Internet Of Things" And FUD

TL;DR, most of the security news about IoT is full of FUD. Always put the risks in context - who can exploit this and what can the attacker do with it. Most story only covers the latter.

Introduction

There is rarely a day without news that another "Internet of Things" got hacked. "Smart" safes, "smart" rifles, "smart" cars, "smart" fridges, "smart" TVs, "smart" alarm systems, "smart" meters, "smart" bulbs, NAS devices, routers. These devices are getting hacked every day. Because most of these devices were never designed with security as a goal, and some of them have been never tested by security professionals, it is no surprise that these things are full of vulnerabilities.

Independent security researchers find these vulnerabilities, write a cool blog post or give a presentation about the vulnerability and the exploit, and the media forgets the constraints just for the sake of more clicks. "We are all doomed" we can read in the news, but sometimes the risks are buried deeply in technical jargon. Please note I blame the news sites here, not the researchers.

http://www.slideshare.net/danielmiessler/iot-attack-surfaces-defcon-2015

There are huge differences between the following risks:

Attackers can directly communicate with the router (or camera) from the Internet without authentication and exploit the vulnerability. This is the worst-case scenario. For example, an automated ransomware attack against your NAS is pretty bad.
Attackers have to position themselves in the same WAN network (e.g. Sprint mobile network in the case of Jeep hacking) to exploit the vulnerability. This is still pretty bad.
The vulnerable code can not be triggered directly from the Internet, but tricks like CSRF can be used to exploit it (details later in this post).
The vulnerable code can not be triggered directly from the Internet, and it uses a protocol/port which prevents Cross Protocol Scripting. Attackers have to access the local network before exploiting this vulnerability.

As it is the case with the worst scenario, one can find a lot of devices connected to the internet. You can always find funny stuff at http://explorer.shodanhq.com/#/explore , or use the nmap screenshot script to find your own stuff :)

Network exposure

Most devices are behind an IPv4 NAT device (e.g. home router), thus can not be reached from the Internet side by default. Except when the device configures the firewall via UPNP. Or the device has a persistence cloud connection, and the cloud can send commands to the device. Or the device uses IPv6 tunneling (e.g. Teredo), thus it is reachable from the Internet. But not every vulnerability on your home network is accessible directly from the Internet. As more and more devices and networks will support IPv6, this scenario might change, but I hope most home routers will come with a default deny configuration in their IPv6 firewall module. On the other hand, scanning for IPv6 devices blindly is not feasible due to the large number of IPv6 addresses, but some tricks might work.

If attackers can not access the device directly, there is a way to hack it through the user's browser. Just convince the victim user to visit a website, and via CSRF (Cross Site Request Forgery) and brute-forcing the device IP, it is possible to hack some devices (mostly through HTTP - if the exploit can fit into simple GET or POST commands.

If attackers can not attack the device vulnerability through the Internet directly, or via CSRF, but have connected to the same network - the network exposure shrinks significantly. And when attackers are on the same network as you, I bet you have bigger problems than the security of the IoT devices ...

Recommendations for home users

Don't buy **** you don't need

Disconnect from the power cord the IoT devices you don't need to operate 7*24.

Disable cloud connectivity if it is not necessary. For example, I have a NAS device that can be reached through the "cloud", but I have disabled it by not configuring any default gateway for the device. I prefer connecting to my network via VPN and reach all my stuff through that.

Prevent CSRF attacks. I use two tricks. Don't use the 192.168.0.x - 192.168.10.x network at-home - use an uncommon IP range instead (e.g. 192.168.156.x is better). The second trick is I configured my Adblock plugin in my primary browser to block access to my internal network. And I use another browser whenever I want to access my internal devices. Update: On Firefox you can use NoScript ABE to block access to internal resources.

Check your router configuration:

disable UPnP
check the firewall settings and disable unnecessary port forwards
check for IPv6 settings, and configure the firewall as default deny for incoming IPv6 TCP/UDP.

Change default passwords, especially for services connected to the Internet. Follow password best practices.

Run Nmap to locate new IoT in your home network :)

Run a WiFi scan to locate new WiFi access points. Let me share a personal experience with you. I moved to a new house and brought my own WiFi router with me. I plugged it in, and forget about WiFi. Months later it turned out I had two other WiFi devices in my house - the cable modem had its own integrated WiFi with default passwords printed on the bottom, and the Set-top-box was the same - default WiFi passwords printed on the bottom. And don't forget to scan for ZigBee, Bluetooth, IrDA, FM, ...

Update your devices - in case you have a lot of free time in your hand.

Don't allow your guests to connect to your home network. Set up a separated AP for them. Imagine your nephew stealing your private photos or videos from your NAS or DNLA server.

With great power, comes great responsibility. The less device you own in your house, the less time you need to maintain those.

Read the manuals of your devices. Be aware of the different interfaces. Configure it in a secure way.

Disable Teredo protocol in case you don't need IPv6.

Stop being amazed by junk hacking.

Update: Disable WebRTC: https://www.browserleaks.com/webrtc , in Chrome you can use this extension: https://chrome.google.com/webstore/detail/webrtc-network-limiter/npeicpdbkakmehahjeeohfdhnlpdklia

Update: Prevent against DNS rebind attacks via configuring a DNS server which can block internal IP addresses. OpenDNS can block internal IP, but this is not a default option, you have to configure it.

Recommendations for vendors

For vendors, I recommend at least the followings:

Implement security during Software Development LifeCycle
Continuous security testing and bug bounties
Seamless auto-update
Opt-in cloud connectivity

Recommendations for journalists

Stop FUD. Pretty please.

The questions to ask before losing your head

who can exploit the vulnerability?
what prerequisites do we have about the attack to successfully exploit the vulnerability? Is the attacker already in your home network? If yes, you have probably bigger problems.
what can the attacker do when the exploit is successful?

And last but not least, don't forget that in the case of IoT devices, sometimes users are the product, not the customer. IoT is about collecting data for marketing purposes.

http://blog.open-xchange.com/2015/02/09/iot/

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Urlgrab - A Golang Utility To Spider Through A Website Searching For Additional Links

A golang utility to spider through a website searching for additional links with support for JavaScript rendering.

Install

go get -u github.com/iamstoxe/urlgrab

Features

Customizable Parallelism
Ability to Render JavaScript ^{(including Single Page Applications such as Angular and React)}

Usage

Usage of urlgrab:
  -cache-dir string
        Specify a directory to utilize caching. Works between sessions as well.
  -debug
        Extremely verbose debugging output. Useful mainly for development.
  -delay int
        Milliseconds to randomly apply as a delay between requests. (default 2000)
  -depth int
        The maximum limit on the recursion depth of visited URLs.  (default 2)
  -headless
        If true the browser will be displayed while crawling.
        Note: Requires render-js flag
        Note: Usage to show browser: --headless=false (default true)
  -ignore-query
        Strip the query portion of the URL before determining if we've visited it yet.
  -ignore-ssl
        Scrape pages with invalid SSL certificates
  -js-timeout int
        The amount of seconds before a request to render    javascript should timeout. (default 10)
  -json string
        The filename where we should store the output JSON file.
  -max-body int
        The limit of the retrieved response body in kilobytes.
        0 means unlimited.
        Supply this value in kilobytes. (i.e. 10 * 1024kb = 10MB) (default 10240)
  -no-head
        Do not send HEAD requests prior to GET for pre-validation.
  -output-all string
        The directory where we should store the output files.
  -proxy string
        The SOCKS5 proxy to utilize (format: socks5://127.0.0.1:8080 OR http://127.0.0.1:8080).
        Supply multiple proxies by separating them with a comma.
  -random-agent
        Utilize a random user agent string.
  -render-js
        Determines if we utilize a headless chrome instance to render javascript.
  -root-domain    string
        The root domain we should match links against.
        If not specified it will default to the host of --url.
        Example: --root-domain google.com
  -threads int
        The number of threads to utilize. (default 5)
  -timeout int
        The amount of seconds before a request should timeout. (default 10)
  -url string
        The URL where we should start crawling.
  -urls string
        A file path that contains a list of urls to supply as starting urls.
        Requires --root-domain flag.
  -user-agent string
        A user agent such as (Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:47.0) Gecko/20100101 Firefox/47.0).
  -verbose
        Verbose output

Author
Devin Stokes

Twitter: @DevinStokes
Github: @IAmStoxe

Download Urlgrab

via KitPloitMore information