This Week in Security

240 Articles

This Week In Security: Not A Vulnerability, BGP Bug Propogation, And Press Enter To Hack

September 1, 2023 by 6 Comments

Curl was recently notified of a CVE, CVE-2020-19909, rated at a hair-raising 9.8 on the CVSS scale. And PostgreSQL has CVE-2020-21469, clocking in with a 7.5 severity. You may notice something odd about those two vulnerabilities, but I promise the 2020 date is only the tip of the iceberg here.

Let’s start with PostgreSQL. That vulnerability was only present in version 12.2, which released in February of 2020, and was fixed with the 12.3 release in May of that same year. The problem is a stack buffer overflow, which doesn’t seem to enable code execution, but does cause a denial of service situation. To trigger the bug? Repeatedly send the PostgreSQL daemon the SIGHUP signal.

If you’re familiar with Linux signals, that might sound odd. See, the SIGHUP signal technically indicates the end of a user session, but most daemons use it to indicate a restart or reload request. And to send this signal, a user has to have elevated privileges — elevated enough to simply stop the daemon altogether. Put simply, it’s not a security vulnerability, just a minor bug.

And now on to curl — This one is just bizarre. The issue is a integer overflow in the --retry-delay argument, which specifies in seconds how often curl should retry a failing download. The value is multiplied by 1000 to convert to milliseconds, resulting in an overflow for very large values. The result of that overflow? A smaller value for the retry delay.

[Daniel Stenberg] makes the point that this tale is a wonderful demonstration of the brokenness of the CVE system and NVD’s handling of it. And in this case, it’s hard not to see this as negligence. We have to work really hard to construct a theoretical scenario where this bug could actually be exploited. The best I’ve been able to come up with is an online download tool, where the user can specify part of the target name and a timeout. If that tool had a check to ensure that the timeout was large enough to avoid excess traffic, this bug could bypass that check. Should we be assigning CVEs for that sort of convoluted, theoretical attack?

But here’s the thing, that attack scenario should rate something like a CVSS of 4.8 at absolute worst. NVD assigned this a 9.8. There’s no way you can squint at this bug hard enough to legitimately rank it that severe. At the time of writing, the NVD lists this as “UNDERGOING REANALYSIS”.
Continue reading “This Week In Security: Not A Vulnerability, BGP Bug Propogation, And Press Enter To Hack” →

This Week In Security: WinRAR, DNS Disco, And No Silver Bullets

August 25, 2023 by 1 Comment

So what does WinRAR, day trading, and Visual Basic have in common? If you guessed “elaborate malware campaign aimed at investment brokers”, then you win the Internet for the day. This work comes from Group-IB, another cybersecurity company with a research team. They were researching a malware known as DarkMe, and found an attack on WinRAR being used in the wild, using malicious ZIP files being spread on a series of web forums for traders.

Among the interesting tidbits of the story, apparently at least one of those forums locked down the users spreading the malicious files, and they promptly broke into the forum’s back-end and unlocked their accounts. The vulnerability itself is interesting, too. A rigged zip file is created with identically named image file and folder containing a script. The user tries to open the image, but because the zip is malformed, the WinRAR function gets confused and opens the script instead.

Based on a user’s story from one of those forums, it appears that the end goal was to break into the brokers’ trading accounts, and funnel money into attacker accounts. The one documented case only lost $2 worth of dogecoin.

There was one more vulnerability found in WinRAR, an issue when processing malicious recovery volumes. This can lead to code execution due to a memory access error. Both issues were fixed with release 6.23, so if you still have a WinRAR install kicking around, make sure it’s up to date! Continue reading “This Week In Security: WinRAR, DNS Disco, And No Silver Bullets” →

This Week In Security: TunnelCrack, Mutant, And Not Discord

August 18, 2023 by 10 Comments

Up first is a clever attack against VPNs, using some clever DNS and routing tricks. The technique is known as TunnelCrack (PDF), and every VPN tested was vulnerable to one of the two attacks, on at least one supported platform.
Continue reading “This Week In Security: TunnelCrack, Mutant, And Not Discord” →

This Week In Security: It’s Con Season

August 11, 2023 by 8 Comments

It must be Blackhat/DEFCON season. Up first in the storm of named vulnerabilities, we have Downfall. The PDF has the juicy details here. It’s quite similar to the Zenbleed issue from last week, in that it abuses speculative execution to leak data via a hidden register. Unlike Zenbleed, this isn’t direct access, but using cache timing analysis to extract individual bytes using a FLUSH+RELOAD approach.

The key to the vulnerability is the gather instruction, which pulls data from multiple locations in memory, often used to run a followup instruction on multiple bytes of data at once. The gather instruction is complex, takes multiple clock cycles to execute, and uses several tricks to execute faster, including managing buffers to avoid multiple reads. In certain cases, that instruction can be interrupted before it completes, leaving the data in the cache. And this data can be speculatively accessed and the values leaked through timing analysis.

This flaw affects 6th generation Intel Core processors through 11th. Mitigations are already rolling out via a microcode update, but do carry a performance hit for gather instructions. Continue reading “This Week In Security: It’s Con Season” →

This Week In Security: Your Car’s Extended Warranty, Seizing The Fediverse, And Arm MTE

August 4, 2023 by 15 Comments

If you’ve answered as many spam calls as I have, you probably hear the warranty scam robocall in your sleep: “We’ve been trying to reach you about your car’s extended warranty.” That particular robocalling operation is about to run out of quarters, as the FCC has announced a nearly $300 million fine levied against that particular operation. The scammers had a list of 500 million phone numbers, and made over five billion calls in three months. Multiple laws were violated, including some really scummy behavior like spoofing employer caller ID, to try to convince people to pick up the call.

Now, that record-setting fine probably isn’t ever going to get paid. The group of companies on the hook for the amount don’t really exist in a meaningful way. The individuals behind the scams are Roy Cox and Aaron Jones, who have already been fined significant amounts and been banned from making telemarketing calls. Neither of those measures put an end to the problem, but going after Avid Telecom, the company that was providing telephone service, did finally put the scheme down.

Mastodon Data Scooped

There are some gotchas to Mastodon. Direct Messages aren’t end-to-end encrypted, your posts are publicly viewable, and if your server operator gets raided by law enforcement, your data gets caught up in the seizure.

The background here is the administrator of the server in question had an unrelated legal issue, and was raided by FBI agents while working on an issue with the Mastodon instance. As a result, when agents seized electronics as evidence, a database backup of the instance was grabbed too. While Mastodon posts are obviously public by design, there is some non-public data to be lost. IP addresses aren’t exactly out of reach of law enforcement, it’s still a bit of personal information that many of us like to avoid publishing. Then there’s hashed passwords. While it’s better than plaintext passwords, having your password hash out there just waiting to be brute-forced is a bit disheartening. But the one that really hurts is that Mastodon doesn’t have end-to-end encryption for private messages. Continue reading “This Week In Security: Your Car’s Extended Warranty, Seizing The Fediverse, And Arm MTE” →

This Week In Security: Zenbleed, Web Integrity, And More!

July 28, 2023 by 9 Comments

Up first is Zenbleed, a particularly worrying speculative execution bug, that unfortunately happens to be really simple to exploit. It leaks data from function like strlen, memcpy, and strcmp. It’s vulnerable from within virtual machines, and potentially from within the browser. The scope is fairly limited, though, as Zenbleed only affects Zen 2 CPUs: that’s the AMD Epyc 7002 series, the Ryzen 3000 series, and some of the Ryzen 4000, 5000, and 7020 series of CPUs, specifically those with the built-in Radeon graphics.

And at the heart of problem is a pointer use-after-free — that happens inside the CPU itself. We normally think of CPU registers as fixed locations on the silicon. But in the case of XMM and YMM registers, there’s actually a shared store of register space, and the individual registers are mapped into that space using a method very reminiscent of pointers.

Continue reading “This Week In Security: Zenbleed, Web Integrity, And More!” →

This Week In Security: Dating App, WooCommerce, And OpenSSH

July 21, 2023 by 4 Comments

Up first this week is a report from vpnMentor, covering the unsecured database backing a set of dating apps, including 419 Dating. The report is a bit light on the technical details, like what sort of database this was, or how exactly it was accessed. But the result is 2.3 million exposed records, containing email address, photos — sometimes explicit, and more. Apparently also exposed were server backups and logs.

The good news here is that once [Jeremiah Fowler] discovered the database door unlocked and hanging open, he made a disclosure, and the database was secured. We can only hope that it wasn’t discovered by any bad actors in the meantime. The app has now disappeared from the Google Play store, and had just a bit of a sketchy air about it.

WooCommerce Under Siege

Back in March, CVE-2023-28121 was fixed in the WooCommerce plugin for WordPress. The issue here is an authentication bypass that allows an unauthenticated user to commandeer other user accounts.

Within a few months, working exploits had been derived from the details of the patch plugging the hole. It wasn’t hard. A function for determining the current user was explicitly trusting the contents of the X-WCPAY-PLATFORM-CHECKOUT-USER request header. Set that value in a request sent to the server, and ding, you’re administrator.

And now the cows are coming home to roost. Active exploitation started in earnest on July 14, and the folks at Wordfence clocked a staggering 1.3 million exploitation attempts on the 16th. What’s particularly interesting is that the Wordfence data gathering system saw a huge increase in requests for the readme.txt file that indicates the presence of the WooCommerce plugin on a WordPress site. These requests were observed before the attacks got started, making for an interesting early warning system. Continue reading “This Week In Security: Dating App, WooCommerce, And OpenSSH” →