Sunday, May 20, 2018

masscan, macOS, and firewall

One of the more useful features of masscan is the "--banners" check, which connects to the TCP port, sends some request, and gets a basic response back. However, since masscan has it's own TCP stack, it'll interfere with the operating system's TCP stack if they are sharing the same IPv4 address. The operating system will reply with a RST packet before the TCP connection can be established.

The way to fix this is to use the built-in packet-filtering firewall to block those packets in the operating-system TCP/IP stack. The masscan program still sees everything before the packet-filter, but the operating system can't see anything after the packet-filter.

Monday, May 14, 2018

Some notes on eFail

I've been busy trying to replicate the "eFail" PGP/SMIME bug. I thought I'd write up some notes.

PGP and S/MIME encrypt emails, so that eavesdroppers can't read them. The bugs potentially allow eavesdroppers to take the encrypted emails they've captured and resend them to you, reformatted in a way that allows them to decrypt the messages.

Sunday, May 13, 2018

Leaking securely, for White House staffers

Spencer Ackerman has this interesting story about a guy assigned to crack down on unauthorized White House leaks. It's necessarily light on technical details, so I thought I'd write up some guesses, either as a guide for future reporters asking questions, or for people who want to better know the risks when leak information.

It should come as no surprise that your work email and phone are already monitored. They can get every email you've sent or received, even if you've deleted it. They can get every text message you've sent or received, the metadata of every phone call sent or received, and so forth.

Wednesday, April 25, 2018

No, Ray Ozzie hasn't solved crypto backdoors

According to this Wired article, Ray Ozzie may have a solution to the crypto backdoor problem. No, he hasn't. He's only solving the part we already know how to solve. He's deliberately ignoring the stuff we don't know how to solve. We know how to make backdoors, we just don't know how to secure them.

Sunday, April 22, 2018

OMG The Stupid It Burns

This article, pointed out by @TheGrugq, is stupid enough that it's worth rebutting.

The article starts with the question "Why did the lessons of Stuxnet, Wannacry, Heartbleed and Shamoon go unheeded?". It then proceeds to ignore the lessons of those things.

Monday, April 16, 2018

Notes on setting up Raspberry Pi 3 as WiFi hotspot

I want to sniff the packets for IoT devices. There are a number of ways of doing this, but one straightforward mechanism is configuring a "Raspberry Pi 3 B" as a WiFi hotspot, then running tcpdump on it to record all the packets that pass through it. Google gives lots of results on how to do this, but they all demand that you have the precise hardware, WiFi hardware, and software that the authors do, so that's a pain.

My letter urging Georgia governor to veto anti-hacking bill

April 16, 2018

Office of the Governor
206 Washington Street
111 State Capitol
Atlanta, Georgia 30334

Re: SB 315

Dear Governor Deal:

I am writing to urge you to veto SB315, the "Unauthorized Computer Access" bill.

The cybersecurity community, of which Georgia is a leader, is nearly unanimous that SB315 will make cybersecurity worse. You've undoubtedly heard from many of us opposing this bill. It does not help in prosecuting foreign hackers who target Georgian computers, such as our elections systems. Instead, it prevents those who notice security flaws from pointing them out, thereby getting them fixed. This law violates the well-known Kirchhoff's Principle, that instead of secrecy and obscurity, that security is achieved through transparency and openness.

That the bill contains this flaw is no accident. The justification for this bill comes from an incident where a security researcher noticed a Georgia state election system had made voter information public. This remained unfixed, months after the vulnerability was first disclosed, leaving the data exposed. Those in charge decided that it was better to prosecute those responsible for discovering the flaw rather than punish those who failed to secure Georgia voter information, hence this law.

Too many security experts oppose this bill for it to go forward. Signing this bill, one that is weak on cybersecurity by favoring political cover-up over the consensus of the cybersecurity community, will be part of your legacy. I urge you instead to veto this bill, commanding the legislature to write a better one, this time consulting experts, which due to Georgia's thriving cybersecurity community, we do not lack.

Thank you for your attention.

Robert Graham
(formerly) Chief Scientist, Internet Security Systems

Sunday, April 15, 2018

Let's stop talking about password strength

Picture from EFF -- CC-BY license
Near the top of most security recommendations is to use "strong passwords". We need to stop doing this.