This Week In Security: Intel Atoms Spill Secrets, ICMP Poisons DNS, And The Blacksmith

November 19, 2021 by 21 Comments

Intel has announced CVE-2021-0146, a vulnerability in certain processors based on the Atom architecture, and the Trusted Platform Module (TPM) is at the center of the problem. The goal of the system around the TPM is to maintain system integrity even in the case of physical access by an attacker, so the hard drive is encrypted using a key stored in a secure chip on the motherboard. The TPM chip holds this encryption key and provides it during the boot process. When combined with secure boot, this is a surprisingly effective way to prevent tampering or data access even in the case of physical access. It’s effective, at least, when nothing goes wrong.

Earlier this year, we covered a story where the encryption key could be sniffed directly from the motherboard, by tapping the traces connecting the TPM to the CPU. It was pointed out that TPM 2.0 can encrypt the disk encryption key on the traces, making this attack impossible.

The entire Trusted Compute Model is based on the premise that the CPU itself is trustworthy. This brings us back to Intel’s announcement that a debug mode could be enabled via physical access. In this debug mode, the CPU master key can be extracted, leading to complete compromise. The drive encryption key can be recovered, and unsigned firmware can be loaded to the Management Engine. This means data in the TPM enclave and the TPM-stored encryption key can be compromised. Updated firmware is rolling out through motherboard vendors to address the problem. Continue reading “This Week In Security: Intel Atoms Spill Secrets, ICMP Poisons DNS, And The Blacksmith” →

This Week In Security: OpenOffice Vulnerable, IOS Vulnerable, Outlook… You Get The Idea

October 1, 2021 by 13 Comments

We start this week with a good write-up by [Eugene Lim] on getting started on vulnerability hunting, and news of a problem in OpenOffice’s handling of DBase files. [Lim] decided to concentrate on a file format, and picked the venerable dbase format, .dbf. This database format was eventually used all over the place, and is still supported in Microsoft Office, Libreoffice, and OpenOffice. He put together a fuzzing approach using Peach Fuzzer, and found a handful of possible vulnerabilities in the file format, by testing a very simple file viewer that supported the format. He managed to achieve code execution in dbfview, but that wasn’t enough.

Armed with a vulnerability in one application, [Lim] turned his attention to OpenOffice. He knew exactly what he was looking for, and found vulnerable code right away. A buffer is allocated based on the specified data type, but data is copied into this buffer with a different length, also specified in the dbase file. Simple buffer overflow. Turning this into an actual RCE exploit took a bit of doing, but is possible. The disclosure didn’t include a full PoC, but will likely be reverse engineered shortly.

Normally we’d wrap by telling you to go get the update, but OpenOffice doesn’t have a stable release with this fix in it. There is a release candidate that does contain the fix, but every stable install of OpenOffice in the world is currently vulnerable to this RCE. The vulnerability report was sent way back on May 4th, over 90 days before full disclosure. And what about LibreOffice, the fork of OpenOffice? Surely it is also vulnerable? Nope. LibreOffice fixed this in routine code maintenance back in 2014. The truth of the matter is that when the two projects forked, the programmers who really understood the codebase went to LibreOffice, and OpenOffice has had a severe programmer shortage ever since. I’ve said it before: Use LibreOffice, OpenOffice is known to be unsafe. Continue reading “This Week In Security: OpenOffice Vulnerable, IOS Vulnerable, Outlook… You Get The Idea” →

This Week In Security: Ghoscript In Imagemagick, Solarwinds, And DHCP Shenanigans

September 10, 2021 by 3 Comments

A PoC was just published for a potentially serious flaw in the Ghostscript interpreter. Ghostscript can load Postscript, PDF, and SVG, and it has a feature from Postscript that has been a continual security issue: the %pipe% command. This command requests the interpreter to spawn a new process — It’s RCE as part of the spec. This is obviously a problem for untrusted images and documents, and Ghostscript has fixed security vulnerabilities around this mis-feature several times over the years.

This particular vulnerability was discovered by [Emil Lerner], and described at ZeroNights X. That talk is available, but in Russian. The issue seems to be a bypass of sorts, where the pipe command appears to be working in the /tmp/ directory, but a simple semicolon allows for an arbitrary command to be executed. Now why is this a big deal? Because ImageMagick uses Ghostscript to open SVG images by default on some distributions, and ImageMagick is often used for automatically resizing and converting images for web sites. In [Emil]’s presentation, he uses this flaw as part of an attack chain against three different companies.

I was unable to reproduce the flaw on my Fedora install, but I haven’t found any notice of it being fixed in the Ghostscript or Imagemagick changelogs either. It’s unclear if this problem has already been fixed, or if this is a true 0-day for some platforms. Either way, expect attackers to start trying to make use of it.

Continue reading “This Week In Security: Ghoscript In Imagemagick, Solarwinds, And DHCP Shenanigans” →

This Week In Security: PunkBuster, NAT, NAS And MP3s

October 2, 2020 by 4 Comments

Ah, the ever-present PDF, and our love-hate relationship with the format. We’ve lost count of how many vulnerabilities have been fixed in PDF software, but it’s been a bunch over the years. This week, we’re reminded that Adobe isn’t the only player in PDF-land, as Foxit released a round of updates, and there were a couple serious problems fixed. Among the vulnerabilities, a handful could lead to RCE, so if you use or support Foxit users, be sure to go get them updated.

PunkBuster

Remember PunkBuster? It’s one of the original anti-cheat solutions, from way back in 2000. The now-classic Return to Castle Wolfenstein was the first game to support PunkBuster to prevent cheating. It’s not the latest or greatest, but PunkBuster is still running on a bunch of game servers even today. [Daniel Prizmant] and [Mauricio Sandt] decided to do a deep dive project on PunkBuster, and happened to find an arbitrary file-write vulnerability, that could easily compromise a PB enabled server.

One of the functions of PunkBuster is a remote screenshot capture. If a server admin thinks a player is behaving strangely, a screenshot request is sent. I assume this targets so-called wallhack cheats — making textures transparent, so the player can see through walls. The problem is that the server logic that handles the incoming image has a loophole. If the filename ends in .png as expected, some traversal attack checks are done, and the png file is saved to the server. However, if the incoming file isn’t a png, no transversal detection is done, and the file is naively written to disk. This weakness, combined with the stateless nature of screenshot requests, means that any connected client can write any file to any location on the server at any time. To their credit, even Balance, the creators of PunkBuster, quickly acknowledged the issue, and have released an update to fix it.

Continue reading “This Week In Security: PunkBuster, NAT, NAS And MP3s” →

This Week In Security: Leaking Partial Bits, Apple News, And Overzealous Contact Tracing

May 29, 2020 by 11 Comments

Researchers at the NCCGroup have been working on a 5-part explanation of a Windows kernel vulnerability, targeting the Kernel Transaction Manager (KTM). The vulnerability, CVE-2018-8611, is a local privilege escalation bug. There doesn’t seem to be a way to exploit this remotely, but it is an interesting bug, and NCCGroup’s work on it is outstanding.

They start with a bit of background on what the KTM is, and why one might want to use it. Next is a handy guide to reverse engineering Microsoft patches. From there, they describe the race condition and how to actually exploit it. They cover a wide swath in the series, so go check it out.

Left4Dead 2

Just a reminder that bugs show up where you least expect them, [Hunter Stanton] shares his story of finding a code execution bug in the popular Valve game, Left4Dead 2. Since the game’s code isn’t available to look at, he decided to go the route of fuzzing. The specific approach he took was to fuzz the navigation mesh data, part of the data contained in each game map. Letting the Basic Fuzzing Framework (BFF) run for three days turned up a few possible crashes, and the most promising turned out to have code execution potential. [Hunter] submitted the find through Valve’s HackerOne bug bounty program, and landed a cool $10k bounty for his trouble.

While it isn’t directly an RCE, [Hunter] does point out that malicious mesh data could be distributed with downloadable maps on the Steam workshop. Alternatively, it should be possible to set up a fake game server that distributes the trapped map. Continue reading “This Week In Security: Leaking Partial Bits, Apple News, And Overzealous Contact Tracing” →

This Week In Security: Psychic Paper, Spilled Salt, And Malicious Captchas

May 8, 2020 by 10 Comments

Apple recently patched a security problem, and fixed the Psychic Paper 0-day. This was a frankly slightly embarrasing flaw that [Siguza] discovered in how iOS processed XML data in an application’s code signature that allowed him access to any entitlement on the iOS system, including running outside a sandbox.

Entitlements on iOS are a set of permissions that an application can request. These entitlements range from the aforementioned com.apple.private.security.no-container to platform-application, which tells the system that this is an official Apple application. As one would expect, Apple controls entitlements with a firm grip, and only allows certain entitlements on apps hosted on their official store. Even developer-signed apps are extremely limited, with only two entitlements allowed.

This system works via an XML list document that is part of the signed application. XML is a relative of HTML, but with a stricter set of rules. What [Siguza] discovered is that iOS contains 4 different XML parsers, and they deal with malformed XML slightly differently. The kicker is that one of those parsers does the security check, while a different parser is used for that actual permission implementation. Is it possible that this mismatch could contain a vulnerability? Of course there is.
Continue reading “This Week In Security: Psychic Paper, Spilled Salt, And Malicious Captchas” →

This Week In Security: Firewall 0-day, Apple’s Response, And An Android Bluetooth Bug

May 1, 2020 by 8 Comments

Sophos firewall appliances are actively being attacked by a 0-day exploit chain that originates with a SQL injection. That injection is a nasty one, as it can be launched from the WAN user portal. The observed attack used that vulnerability to inject a shell command into the device database, where it would eventually be run automatically. If you have an affected Sophos device, go check that the hotfix was automatically installed.

While the vulnerability was a bad one, Sophos’ response here is laudable. They publicly disclosed the attack less than 24 hours after they were notified of it’s existence in the wild, and began rolling a fix out within three days. Additionally, Sophos engineers did a really detailed write-up (linked above) giving us all the details of the attack. The hotfix that closes the vulnerability also attempts to clean up the infection, although there are some additional manual steps that are suggested if your device was compromised. Continue reading “This Week In Security: Firewall 0-day, Apple’s Response, And An Android Bluetooth Bug” →