Debian Long Term Support / LTS Security Information / 2019 / Security Information -- DLA-1952-1 rsyslog

Debian Security Advisory

DLA-1952-1 rsyslog -- LTS security update

Date Reported:

09 Oct 2019

Affected Packages:

rsyslog

Vulnerable:

Yes

Security database references:

In Mitre's CVE dictionary: CVE-2019-17041, CVE-2019-17042.

More information:

It was discovered that there were two vulnerabilities in the rsyslog system/kernel logging daemon in the parsers for AIX and Cisco log messages respectfully.

• CVE-2019-17041

  An issue was discovered in Rsyslog v8.1908.0. contrib/pmaixforwardedfrom/pmaixforwardedfrom.c has a heap overflow in the parser for AIX log messages. The parser tries to locate a log message delimiter (in this case, a space or a colon) but fails to account for strings that do not satisfy this constraint. If the string does not match, then the variable lenMsg will reach the value zero and will skip the sanity check that detects invalid log messages. The message will then be considered valid, and the parser will eat up the nonexistent colon delimiter. In doing so, it will decrement lenMsg, a signed integer, whose value was zero and now becomes minus one. The following step in the parser is to shift left the contents of the message. To do this, it will call memmove with the right pointers to the target and destination strings, but the lenMsg will now be interpreted as a huge value, causing a heap overflow.

• CVE-2019-17042

  An issue was discovered in Rsyslog v8.1908.0. contrib/pmcisconames/pmcisconames.c has a heap overflow in the parser for Cisco log messages. The parser tries to locate a log message delimiter (in this case, a space or a colon), but fails to account for strings that do not satisfy this constraint. If the string does not match, then the variable lenMsg will reach the value zero and will skip the sanity check that detects invalid log messages. The message will then be considered valid, and the parser will eat up the nonexistent colon delimiter. In doing so, it will decrement lenMsg, a signed integer, whose value was zero and now becomes minus one. The following step in the parser is to shift left the contents of the message. To do this, it will call memmove with the right pointers to the target and destination strings, but the lenMsg will now be interpreted as a huge value, causing a heap overflow.

For Debian 8 Jessie, these problems have been fixed in version 8.4.2-1+deb8u3.

We recommend that you upgrade your rsyslog packages.

Further information about Debian LTS security advisories, how to apply these updates to your system and frequently asked questions can be found at: https://wiki.debian.org/LTS