Security
Enforcing password strength
There have been a lot of high-profile site compromises of late (kernel.org, Linux.com, MySQL, WineHQ, ...), most or all of which have led to password disclosure. Hopefully all of the disclosed passwords were stored as hash values, but, even so, sufficiently motivated attackers may well be able to crack some of the passwords via brute force or other means. Because passwords are often reused between sites, these compromises have made projects and others concerned about the security of the passwords granting access to their sites.
That concern led Kevin Fenzi of the Fedora infrastructure team to put out a message noting that all Fedora Account
System (FAS) users are required to change their password (and SSH public
keys, more about
that below). As Fenzi said, the password change is not because of any
known compromise of the Fedora infrastructure, but is, instead, a reaction
to the recent compromises: "due to the
large number of high profile sites with security breaches in recent
months, that this is a great time for all Fedora contributors and users
to review their security settings and move to 'best practices' on their
machines.
" Part of those "best practices" is to have a strong
password, so Fedora is enforcing some rules on the new passwords:
- Nine or more characters with lower and upper case letters, digits and punctuation marks.
- Ten or more characters with lower and upper case letters and digits.
- Twelve or more characters with lower case letters and digits
- Twenty or more characters with all lower case letters.
- No maximum length.
I asked Fenzi in an email where the rules came from, and he pointed me to a Fedora infrastructure bug ticket and the report [PDF] from the University of Amsterdam that it references. That report looks at various password cracking methods and estimates that using those guidelines (actually just the first three) will result in passwords that will take ten years or more to crack at 2 billion guesses per second. That rate was an average of what the researchers found that a modern GPU-equipped system could guess for several different hash algorithms.
As Przemek Klosowski points out, the number of possibilities for each kind of password differ widely. There is a math error in the length-12 case (should be (24+10)^12), and evidently Klosowski is only considering 24 letters, rather than the 26 in English, but his conclusion still stands: the number of possibilities are ten orders of magnitude apart from the first to the last rule. In the end, that doesn't really matter, as long as the weakest choice is sufficient.
Most who commented on the requirement were not particularly annoyed by the password change mandate, but the same cannot be said about the SSH key requirement. SSH users may tend to be more security savvy and are thus less likely to have lost control of their private SSH key than they are to have an easily cracked password—though of course that's no guarantee. But if the private SSH key that corresponds to the public key installed on the FAS servers has been compromised, it's likely that's because the owner's system has been breached. If that's the case, generating a new SSH key on a compromised system will likely only result in another compromised key. In addition, a massive SSH key flag day has its own dangers as Simo Sorce points out:
There is a strong belief that the kernel.org compromise was done via a compromised SSH key, however, so the infrastructure team is requiring folks to change their keys. Many are not happy about it, including Sorce who goes on to say:
If you have evidence of contributors being careless with SSH keys the only recourse is to identify and educate the offenders requiring them to change those keys and not have a 'hit 100 to educate 1' policy that serves little or no purpose.
Sorce's complaint is a reasonable one. Unfortunately, it's hard to know whose keys may have been compromised (or, indeed, if any have been compromised at all) as several folks mentioned. By bringing it up and requiring everyone to change their keys, it may result in better security—and will at least raise the awareness level of the problem, which could result in better security practices by some who were being lax. It is undoubtedly annoying to those who have been careful with their keys, but it isn't that hard to generate and use a new key, even if it is only used for FAS.
Raising the level of awareness of these issues is perhaps the only good thing that has come from these high-profile break-ins. It is pretty easy to get complacent about security, reuse passwords on many sites, have password-less SSH keys, and so on. Events like the kernel.org breach can help break us all of our lax security habits. Certainly many sites, projects, and organizations—even those who haven't suffered a breach—are looking at their security practices; it's a good time for individuals to do so as well.
Passwords are only part of the story, of course, but they tend to be on the "front-line" of the security of our systems, so it is a good place to start. As xkcd so eloquently put it, the time for relatively short but "hard" to guess passwords may well be behind us: pass phrases are more easily remembered and less easily cracked. It's good to see that Fedora is not enforcing a limit on the password length, it's likely that many other sites do have a fairly short limit that will make using pass phrases harder. The Fedora rules do provide some good guidelines to follow when creating passwords or phrases.
Having too many passwords is almost as bad as having too few, because
managing them securely can be quite a headache. One suggestion that Fenzi
made is to use a
password manager program like "revelation, gnome-keyring, seahorse, or keepassx
".
Looking more closely at those kinds of applications is on my to-do list, for both
personal and professional reasons. Look for an article on that topic to
appear on your
virtual doorstep in the near future.
Brief items
Security quotes of the week
Nevertheless, the virus has sparked a bit of a firestorm in military circles. Not only were officials in charge kept out of the loop about an infection in America's weapon and surveillance system of choice, but the surprise surrounding that infection highlights a flaw in the way the U.S. military secures its information infrastructure: There's no one in the Defense Department with his hand on the network switch. In fact, there is no one switch to speak of.
An analysis of alleged German governmental malware
The Chaos Computer Club claims to have analyzed a rootkit used by the German government. "The malware can not only siphon away intimate data but also offers a remote control or backdoor functionality for uploading and executing arbitrary other programs. Significant design and implementation flaws make all of the functionality available to anyone on the internet."
WineHQ database compromised
Codeweavers has announced that access to the WineHQ database has been compromised. "On the one hand, we saw no evidence of harm to any database. We saw no evidence of any attempt to change the database (and candidly, using the real appdb or bugzilla is the easy way to change the database). Unfortunately, the attackers were able to download the full login database for both the appdb and bugzilla. This means that they have all of those emails, as well as the passwords. The passwords are stored encrypted, but with enough effort and depending on the quality of the password, they can be cracked." Anybody who has reused a password stored there probably wants to make some changes fairly soon.
New vulnerabilities
apache: mod_proxy reverse proxy exposure
| Package(s): | apache | CVE #(s): | CVE-2011-3368 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Created: | October 10, 2011 | Updated: | November 10, 2011 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Description: | From the Mandriva advisory:
The mod_proxy module in the Apache HTTP Server 1.3.x through 1.3.42, 2.0.x through 2.0.64, and 2.2.x through 2.2.21 does not properly interact with use of (1) RewriteRule and (2) ProxyPassMatch pattern matches for configuration of a reverse proxy, which allows remote attackers to send requests to intranet servers via a malformed URI containing an initial @ (at sign) character. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Alerts: |
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cups: arbitrary code execution
| Package(s): | cups | CVE #(s): | CVE-2011-3170 | ||||||||||||
| Created: | October 10, 2011 | Updated: | October 12, 2011 | ||||||||||||
| Description: | From the Mandriva advisory:
The gif_read_lzw function in filter/image-gif.c in CUPS 1.4.8 and earlier does not properly handle the first code word in an LZW stream, which allows remote attackers to trigger a heap-based buffer overflow, and possibly execute arbitrary code, via a crafted stream, a different vulnerability than CVE-2011-2896 (CVE-2011-3170). | ||||||||||||||
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cyrus-imapd: access restriction bypass
| Package(s): | cyrus-imapd-2.2 | CVE #(s): | CVE-2011-3372 | ||||||||||||||||||||||||||||||||||||||||
| Created: | October 7, 2011 | Updated: | October 14, 2011 | ||||||||||||||||||||||||||||||||||||||||
| Description: | From the Debian advisory: CVE-2011-3372: Stefan Cornelius of Secunia Research discovered that the command processing of the NNTP server implementation (nttpd) of cyrus-imapd is not properly implementing access restrictions for certain commands and is not checking for a complete, successful authentication. An attacker can use this flaw to bypass access restrictions for some commands and, e.g. exploit CVE-2011-3208 without proper authentication. | ||||||||||||||||||||||||||||||||||||||||||
| Alerts: |
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kdelibs: certificate spoofing
| Package(s): | kdelibs | CVE #(s): | CVE-2011-3365 CVE-2011-3366 | ||||||||||||||||||||||||||||||||||||||||||||
| Created: | October 11, 2011 | Updated: | November 10, 2011 | ||||||||||||||||||||||||||||||||||||||||||||
| Description: | From the KDE advisory:
When displaying a security dialog with a certificate, KSSL does not properly force its QLabels to use QLabel::PlainText. As a result, if given a certificate containing rich text in its fields, it will render the rich text. Specifically, a certificate containing a common name (CN) that has a table element will cause the second line of the table to be displayed. This can allow spoofing of the certificate's common name. | ||||||||||||||||||||||||||||||||||||||||||||||
| Alerts: |
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kernel: two information leaks
| Package(s): | kernel | CVE #(s): | CVE-2011-1161 CVE-2011-1162 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Created: | October 6, 2011 | Updated: | November 28, 2011 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Description: | According to the Red Hat bugzilla entry, both of these are information leaks of some kind in the TPM driver. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Alerts: |
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kernel: multiple vulnerabilities
| Package(s): | kernel | CVE #(s): | CVE-2011-2521 CVE-2011-2898 | ||||||||||||||||||||||||||||
| Created: | October 6, 2011 | Updated: | October 12, 2011 | ||||||||||||||||||||||||||||
| Description: | From the Red Hat advisory: A flaw was found in the Linux kernel's Performance Events implementation. It could falsely lead the NMI (Non-Maskable Interrupt) Watchdog to detect a lockup and panic the system. A local, unprivileged user could use this flaw to cause a denial of service (kernel panic) using the perf tool. (CVE-2011-2521, Moderate) Flaws were found in the tpacket_rcv() and packet_recvmsg() functions in the Linux kernel. A local, unprivileged user could use these flaws to leak information to user-space. (CVE-2011-2898, Low) | ||||||||||||||||||||||||||||||
| Alerts: |
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kernel: denial of service
| Package(s): | kernel | CVE #(s): | CVE-2011-3353 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Created: | October 10, 2011 | Updated: | November 28, 2011 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Description: | From the SUSE advisory:
In the fuse filesystem, FUSE_NOTIFY_INVAL_ENTRY did not check the length of the write so the message processing could overrun and result in a BUG_ON() in fuse_copy_fill(). This flaw could be used by local users able to mount FUSE filesystems to crash the system. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Alerts: |
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libxml2: denial of service
| Package(s): | libxml2 | CVE #(s): | CVE-2011-2821 CVE-2011-2834 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Created: | October 10, 2011 | Updated: | September 27, 2012 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Description: | From the Mandriva advisory:
Double free vulnerabilities in libxml2 allows remote attackers to cause a denial of service or possibly have unspecified other impact via a crafted XPath expression and via vectors related to XPath handling (CVE-2011-2821, CVE-2011-2834). | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Alerts: |
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openswan: denial of service
| Package(s): | openswan | CVE #(s): | CVE-2011-3380 | ||||||||||||||||
| Created: | October 6, 2011 | Updated: | October 14, 2011 | ||||||||||||||||
| Description: | From the Red Hat advisory: A NULL pointer dereference flaw was found in the way Openswan's pluto IKE daemon handled certain error conditions. A remote, unauthenticated attacker could send a specially-crafted IKE packet that would crash the pluto daemon. (CVE-2011-3380) | ||||||||||||||||||
| Alerts: |
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php: arbitrary code execution
| Package(s): | php | CVE #(s): | CVE-2011-3379 | ||||||||||||||||||||
| Created: | October 10, 2011 | Updated: | May 10, 2012 | ||||||||||||||||||||
| Description: | From the Red Hat bugzilla:
It was reported that due to changes in the is_a() function PHP 5.3.7 and 5.3.8 became vulnerable to remote arbitrary code execution when is_a() is used in certain ways. Due to the __autoload() implementation, if a user were able to upload a crafted file, it could be possible to pass the contents of the file as an argument to the __autoload() function which could in turn use that argument as a file to include(). If there was no adequate checking or enforcement of the file to load being, local, this could lead to including a remote script from a remote web site. | ||||||||||||||||||||||
| Alerts: |
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xorg-x11-server: multiple vulnerabilities
| Package(s): | xorg-x11 | CVE #(s): | CVE-2010-4818 CVE-2010-4819 | ||||||||||||||||||||||||||||||||||||||||
| Created: | October 7, 2011 | Updated: | February 28, 2012 | ||||||||||||||||||||||||||||||||||||||||
| Description: | From the Red Hat advisory: Multiple input sanitization flaws were found in the X.Org GLX (OpenGL extension to the X Window System) extension. A malicious, authorized client could use these flaws to crash the X.Org server or, potentially, execute arbitrary code with root privileges. (CVE-2010-4818) An input sanitization flaw was found in the X.Org Render extension. A malicious, authorized client could use this flaw to leak arbitrary memory from the X.Org server process, or possibly crash the X.Org server. (CVE-2010-4819) | ||||||||||||||||||||||||||||||||||||||||||
| Alerts: |
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