Estera Daum was born on 5 August 1918 in Konin, Poland. She was the daughter of Wolf and Chawa Daum. From 7 April 1932 to 28 February 1935, she attended the Polish Commercial School in Gdańsk. In the years 1935–1936, she was employed at the Schaad and Woźniak company [upper case?] in Gdańsk, and, then, in 1937, she worked at the Hirszhorn & Co. Grain Agency, also in that city. In 1938, she worked at a few law firms. From 1 October 1938 until the outbreak of the Second World War, she worked at the Export Campaign in Warsaw.

Soon after the war started, she and her mother moved  to Łódź. Beginning in May 1940, she was the second secretary, after Dora Fuchs, at the ghetto’s Central Secretariat at Bałuty Rynek. She was responsible for, among other things, dealing with ghetto food supplies. On 20 October 1944, she was deported from the ghetto to Oranienburg, in Germany. She then remained in the nearby Lutherstadt Wittenberg labour camp until liberation in 1945.

After the war, she settled in Łódź, at 12 Lipowa. She married Izaak Frenkel. They had three sons. In 1973, she and her family left for Israel.

She testified in trials against Gestapo Commissioner Günther Fuchs (who was sentenced to life in prison) and Gestapo Officer Helmut Krizons, among other war criminals. She died in 2001, in Israel.

Based on Daum’s memoirs, Polish author Elżbieta Cherezińska wrote a  novel entitled "Byłam sekretarką Rumkowskiego" (I was Rumkowski's Secretary).