The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). An example of a network attack is an attacker causing a denial of service by sending a specially crafted TCP packet across a wide area network (e.g., CVE-2004-0230).
Attack Complexity
Low
AC
The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Privileges Required
None
PR
The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction
None
UI
The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges
Scope
Unchanged
S
An exploited vulnerability can only affect resources managed by the same security authority. In the case of a vulnerability in a virtualized environment, an exploited vulnerability in one guest instance would not affect neighboring guest instances.
Confidentiality
None
C
There is no impact on the confidentiality of the system; the attacker does not gain the ability to read any data.
Integrity
None
I
There is no impact on the integrity of the system; the attacker does not gain the ability to modify any files or information on the target system.
Availability
High
A
There is a total shutdown of the affected resource. The attacker can deny access to the system or data, potentially causing significant loss to the organization.
Below is a copy: NSS Netscape Certificate Sequences CERT_DecodeCertPackage() Crash
nss: CERT_DecodeCertPackage() crash with Netscape Certificate Sequences
I noticed that the main entrypoint for decoding DER blobs in NSS, CERT_DecodeCertPackage(), actually handles multiple formats including PEM, PKCS7, and old Netscape Certificate Sequences.
You can generate a Netscape Certificate Sequence with the OpenSSL nseq tool, I just did this:
$ openssl nseq -in mail.google.com.pem -toseq -out nseq.pem
I guessed that this format might not have been as well audited as others, so fuzzed it and it crashed with a NULL deref quickly.
Test case attached, I'm guessing this means any client or server that handles untrusted certificates can be crashed, I didn't try it against Firefox.
You can verify it like this:
$ certutil -d \".\" -A -n test -t \"p,p,p\" -i nss-nseq-crash.der
Segmentation fault
I reported this upstream as a denial of service issue, some network daemons use NSS (like slapd, iirc)
This bug is subject to a 90 day disclosure deadline. After 90 days elapse
or a patch has been made broadly available (whichever is earlier), the bug
report will become visible to the public.
Found by: [email protected]
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