| Filename extension |
.slk |
|---|---|
| Internet media type | application/x-sylk |
| Developed by | Microsoft |
Symbolic Link (SYLK) is a Microsoft file format typically used to exchange data between applications, specifically spreadsheets. SYLK files conventionally have a .slk suffix. Composed of only displayable ANSI characters, it can be easily created and processed by other applications, such as databases.
Microsoft has never published a SYLK specification. Variants of the format are supported by Multiplan, Microsoft Excel, Microsoft Works, OpenOffice.org, LibreOffice[1] and Gnumeric. The format was introduced in the 1980s and has not evolved since 1986.[2]
A commonly encountered (and spurious) 'occurrence' of the SYLK file happens when a comma-separated value (CSV) format is saved with an unquoted first field name of 'ID', that is the first two characters match the first two characters of the SYLK file format. Microsoft Excel (at least to Office 2016) will then emit misleading error messages relating to the format of the file, such as "The file you are trying to open, 'x.csv', is in a different format than specified by the file extension...".[3][4]
SYLK is known to cause security issues, as it allows an attacker to run arbitrary code, offers the opportunity to disguise the attack vector under the benign-looking appearance of a CSV file, and is still enabled by default on recent (2016) versions of Microsoft Excel.[2]
- ^ "LibreOffice Calc - Supported File Formats". 12 November 2016.
- ^ a b Stan Hegt (2019-10-30). "Abusing the SYLK file format". outflank.nl. Retrieved 2019-12-14.
- ^ ""SYLK: File format is not valid" error message when you open file". Retrieved August 18, 2015.
- ^ "Excel CSV import returns an SYLK file format error". 9 January 2012. Retrieved August 18, 2015.