Signing the builds for binary:any updates
The security archive is autobuilt these days. Manual signing should no longer be necessary.
Most failed builds are rescheduled by the buildd admins. Otherwise they need to contacted at ARCH@buildd.debian.org.
Writing the advisory text
There's a fairly standard template for this in the security-tracker repository. You can run the command:
bin/gen-DSA --save <package> <vulnerability> "CVEs" '#bugs'
which will allocate a new DSA id from the list and generate a DSA draft. Don't forget to set $DEBFULLNAME and $DEBEMAIL in the environment.
Make sure to commit data/DSA/list, so that the ID is allocated. In this commit you may also want to include the version number of the fixed package. For example:
[squeeze] - libxml2 2.7.8.dfsg-2+squeeze2 [lenny] - libxml2 2.6.32.dfsg-5+lenny5
Once this is done, you can edit the saved DSA draft to add some information about the vulnerability, you can use an existing DSA from debian-security-announce as an example.
If updating a previous DSA, note what was wrong/missing about the previous one and how this update is different.
When CVE IDs exist for the vulnerability, list them, with a description of the nature of the flaw (buffer overflow, XSS, integer overflow, etc.) and the worst-known exploitability (DoS, privilege escalation, arbitrary code). Note what's possible; don't downplay or overstate the threat.
Give brief acknowledgment to the discoverer of the flaw, if they're known. If multiple people worked to assess the vulnerability, note them too.
Once all builds are available (only email@example.com has access to this) and the advisory text is ready, send a mail to firstname.lastname@example.org. The update will be reviewed and released as described in the following section.