This Week In Security: Getting Back Up To Speed

March 6, 2026 by Mike Kershaw 9 Comments

Editor’s Note: Over the course of nearly 300 posts, Jonathan Bennett set a very high bar for this column, so we knew it needed to be placed in the hands of somebody who could do it justice. That’s why we’re pleased to announce that Mike Kershaw AKA [Dragorn] will be taking over This Week In Security! Mike is a security researcher with decades of experience, a frequent contributor to 2600, and perhaps best known as the creator of the Kismet wireless scanner.

He’ll be bringing the column to you regularly going forward, but given the extended period since we last checked in with the world of (in)security, we thought it would be appropriate to kick things off with a review of some of the stories you may have missed.

Hacking like it’s 2009, or 1996

Hello all! It’s a pleasure to be here, and it already seems like a theme of the new year so far has bringing in the old bugs – what’s old is new again, and 2026 has seen several fixes to some increasingly ancient bugs.

Telnet

Reported on the OpenWall list, the GNU inetd suite brings an update to the telnet server (yes, telnet) that closes a login bug present since 2015 linked to environment variable sanitization.

Under the covers, the telnet daemon uses /bin/login to perform user authentication, but also has the ability to pass environment variables from the client to the host. One of these variables, USER, is passed directly to login — unfortunately this time with no checking to see what it contains. By simply passing a USER variable of “-froot”, login would accept the “-f” argument, or “treat this user as already logged in”. Instant root!

If this sounds vaguely familiar, it might be because the exact same bug was found in the Solaris telnetd service in 2007, including using the “-f” argument in the USER variable. An extremely similar bug targeting other variables (LD_PRELOAD) was found in the FreeBSD telnetd service in 2009, and other historical similar bugs have afflicted AIX and other Unix systems in the past.

Of course, nobody in 2026 should be running a telnet service, especially not exposed to the Internet, but it’s always interesting to see the old style of bugs resurface.

Glibc

Also reported on the OpenWall list, glibc — the GNU LibC library which underpins most binaries on Linux systems, providing kernel interfaces, file and network I/O, string manipulation, and most other common functions programmers expect — has killed another historical bug, present since 1996 in the DNS resolver functions which could be used to expose some locations in the stack.

Although not exploitable directly, the getnetbyaddr resolution functions could still ease in breaking ASLR, making other exploits viable.

Address Space Layout Randomization (ASLR) is a common method of randomizing where in memory a process and its data are loaded, making trivial exploits like buffer overflows much harder to execute. Being able to expose the location of the binary in memory by leaking stack locations weakens this mechanism, possibly exposing a vulnerable program to more traditional attacks.

MSHTML

In February, Microsoft released fixes under CVE-2026-21513 for the MSHTML Trident renderer – the one used in Internet Explorer 5. Apparently still present in Windows, and somehow still accessible through specific shortcut links, it’s the IE5 and Active-X gift that keeps giving, being actively exploited.

Continue reading “This Week In Security: Getting Back Up To Speed” →

Telnet Gets Stubborn Sony Camera Under Control

November 25, 2022 by Tom Nardi 13 Comments

According to [Venn Stone], technical producer over at LinuxGameCast, the Sony a5000 is still a solid option for those looking to shoot 1080p video despite being released back in 2014. But while the camera is lightweight and affordable, it does have some annoying quirks — namely an overlay on the HDMI output (as seen in the image above) that can’t be turned off using the camera’s normal configuration menu. But as it so happens, using some open source tools and the venerable telnet, you can actually log into the camera’s operating system and fiddle with its settings directly.

As explained in the write-up, the first step is to install Sony-PMCA-RE, a cross-platform suite of tools developed for reverse engineering and modifying Sony cameras. With the camera connected via USB, this will allow you to install a program on the camera called Open Memories Tweak. This unlocks some developer options on the camera, such as spawning a telnet server on its WiFi interface.

With the a5000 connected to your wireless network, you point your telnet client to its IP address and will be greeted by a BusyBox interface that should be familiar to anyone who’s played with embedded Linux gadgets. The final step is to invoke the proper command, bk.elf w 0x01070a47 00, which sets the specific address of the camera’s configuration file to zero. This permanently disables the HDMI overlay, though it can be reversed by running the command again and setting the byte back to 01.

As you might expect, the Sony-PMCA-RE package is capable of quite a bit more than just unlocking a telnet server. While it might not be as powerful as a firmware modification such as Magic Lantern for Canon’s hardware, those looking for a hackable camera that won’t break the bank might want to check out the project’s documentation to see what else is possible.

Continue reading “Telnet Gets Stubborn Sony Camera Under Control” →

Android Executes Everything You Type

November 9, 2008 by Eliot 11 Comments

This is one of the more bizarre bugs we’ve ever heard. The T-Mobile G1 has an open root shell that interprets everything you type as a command. It was discovered when a user just happened to type the word ‘reboot’ in a conversation and the phone immediately rebooted. A patch has already been rolled out to fix this issue. It also buttons up the earlier telnetd SUID problem.

[photo: tnkgrl]

Getting Root On The G1

November 5, 2008 by Eliot 27 Comments

If you’ve been holding off on a T-Mobile G1 purchase because you didn’t like the apparent user restrictions, there’s some good news. The Android powered phone comes with an easy button for getting root. Install a terminal app and you can manually start the telnetd service. All that’s left is telenetting into the device and it’ll give you root level access.